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Open Access
Nutrient Management for yield and quality improvement in Kacholam
(Department of Agronomy, College of Horticulture, Vellanikkara, 2012) Kavitha, P R; KAU; Meera, Menon V
Kacholam (Kaempferia galanga L.) is an important medicinal and aromatic plant of the Zingiberaceae family. In India, kacholam is cultivated throughout the plains for the rhizomes. The economic produce of kacholam is the chopped and dried rhizomes of 6-7 months maturity. Dried rhizomes are used in bulk quantities in ayurvedic medicine and in the cosmetic industry. It is used for curing inflammatory wounds, skin disorders, piles, oedema, fever, epilepsy, splenic disorders and asthma. The constituents of the rhizome oil include para methoxy ethyl cinnamate (60.24 % of the oil), ethyl cinnamate (20.66%), cineol, borneol, 3-carene, camphene, kaempferol, kaempferide and cinnamaldehyde. There is immense scope for cultivation of kacholam in Kerala, as the climatic and soil conditions are optimally suited to its growth and development. Kacholam can be grown as an intercrop in coconut gardens and it has attained the status of a cash crop of homesteads. Though there is an approved ad hoc recommendation of organic manures as well as N, P and K for kacholam, there are reports that the K dose is inadequate. Also, considering the low availability and high cost, the present organic manure recommendation of 20 tonnes ha-1 is rather unaffordable. There are also reports about the inadequacy in the availability of secondary nutrients viz., S, Ca and Mg, which may affect yield and quality of kacholam. A field experiment was conducted during 2011-2012 in the coconut garden of Water Management Research Unit, Vellanikkara to evaluate the effect of varying doses of K and secondary nutrients on yield and quality of kacholam. There were 12 treatments with 3 replications each. Treatments consisted of package of practices (POP) recommendation of 20 tonnes farmyard manure along with 50:50:50 kg N, P and K ha-1 and combinations with S, Ca, Mg and extra dose of K applied as first and second top dressing. Rhizomes were planted at a spacing of 20 x 15 cm and planting was done on 3/ 06/ 2011. Harvesting was done seven months after planting. Observations included biometric observations taken at monthly intervals, nutrient contents at 2 ½ and 5 months after planting, and at harvest. Nutrient uptakes was also worked out. Essential oil and oleoresin in rhizomes were also analysed. The soil pH and chemical parameters were analysed before and after the experiment. There were significant differences among treatments with respect to yield, essential oil, oleoresin, nutrient contents and nutrient uptake. With respect to yield, the treatment receiving S applied either at first top dressing or at second top dressing and that with S, Ca and Mg recorded highest yields as compared to other treatments. Essential oil content also showed the same trend as that of yield. But in case of oleoresin, the content was more only in the treatments receiving S as first and second top dressing. This treatment resulted in highest uptake of all nutrients except Ca at harvest. Application of the secondary nutrients thus had a direct positive effect on yield and quality. Changing the N:K ratio of present NPK recommendation resulted in reduction of yield and other quality parameters. The yield and quality parameters with the reduced organic manure dose were found similar to the present POP. Increased phosphorus content of soil observed after experimentation indicated the possibility of reducing the recommended phosphorus dose. Supplementing S, Ca and Mg with a reduced organic manure dose is also to be tested.
Open Access
Production potential of cereal fodder crops under various tillage practices in rice fallows.
(Department of Agronomy, College of Horticulture, Vellanikkara, 2011) Gintu, George; KAU; Prameela, P
In order to test the feasibility of raising cereal fodders in rice fallows under various tillage systems an experiment entitled “Production potential of cereal fodder crops under various tillage practices in rice fallows” was conducted at the Department of Agronomy, College of Horticulture, Vellanikkara, Thrissur, Kerala. The experiment was laid out in split plot design with four replications during the period from November 2009 to February 2010. The main plots had tillage practices as treatments which included zero tillage with and without herbicide application (M1 and M2), minimum tillage (M3) and normal tillage (M4). The subplots had three treatments, viz., fodder cereals; maize (S1), sorghum (S2) and bajra (S3). Analysis of data on herbage yield of the three fodders under different tillage practices showed that the herbicide based zero tillage, minimum tillage and normal tillage practices resulted in comparable yields (20.72, 18.72 and 18.08 t/ha). Zero tillage without herbicide application resulted in significantly lower yield (11.69 t/ha). Growth parameters like plant height, leaf area index, leaf stem ratio, shoot root ratio etc. recorded at various growth stages also showed the favourable influence of minimum and herbicide based zero tillage on plant growth. Among the cereal fodders, maize recorded significantly higher yield of 20.19 t/ha followed by sorghum with 15.91 t/ha and bajra with 15.81 t/ha. Considering tillage practices and crops together, the highest B: C ratio of 3.31 was realized when maize was grown under herbicide based zero tillage closely followed by maize under minimum tillage with a B: C ratio of 3.24. Of the other two crops, bajra was found to be more profitable than sorghum. Like maize, herbicide based zero tillage resulted in a higher B: C ratio (3.0) for bajra than other tillage treatments. The yield reduction in zero tillage without herbicide application was mainly due to weeds. A study of weed spectrum showed that dicots were the major weed flora followed by grasses and sedges. The weed population and weed dry matter production were the highest in zero tillage without herbicide application followed by minimum and herbicide based tillage and the least was in normal tillage. Weed dry matter production in zero tilled without herbicide plot was 1545 kg/ha compared to a much lower dry matter accumulation of 193 kg/ha in normal tillage plot. The silage made from all the three cereal fodders was found to be of good quality with golden yellow colour, pleasant smell and a pH ranging from 3.8 to 4.2. In silage prepared without the addition of molasses, pH was found to be slightly higher (4.2) compared to silage prepared with molasses as additive (3.9). The study revealed that fodder maize under herbicide based zero tillage was the best with regard to yield and B: C ratio. However, for a herbicide free production system, maize grown under minimum tillage is preferred due to its equally good performance.
Open Access
Production protocol for organic tomato : (lycopersicon esculentum mill.).
(Department of Agronomy, College of Agriculture, Vellayani, 2011) Abijith, Kumar V P; KAU; Girija, Devi L (Guide)
The research project entitled ‘Production protocol for organic tomato (Lycopersicon esculentum Mill.)’ was conducted at the Instructional Farm attached to the College of Agriculture, Vellayani during the year 2009-2010 to study the effects of organic nutrition and spacing and their interaction upon growth, yield, quality and nutrient uptake of tomato and to assess the residual effect of organic nutrition on the succeeding crop. The experiment was laid out in factorial randomized block design (RBD) with three replications. The treatments consisted of four levels of nutrients, N1 (full nitrogen substitution as organic), N2 (75% nitrogen only and as organic), N3 (50% nitrogen only and as organic) and N4 (Package of Practices Recommendations ‘Crops’: 2007 of Kerala Agricultural University) and three spacing viz., S1 (60 cm x 60 cm), S2 (60 cm x 45 cm) and S3 (60 cm x 30 cm). Before transplanting, the seedlings were given a root dip in Pseudomonas flourescens culture against bacterial wilt disease. The experiment was laid out as 4 x 3 factorial randomized block design (FRBD) with 3 replications. The number of treatments were 12 replication-1. Common treatments such as neem seed oil-garlic emulsion spray, pseudomonas spraying, trichoderma incorporation in the soil and uniform mulching at different intervals were also undertaken. From the results it was found that integrated supply of nutrients through FYM and chemical fertilizers gave the highest fruit yield in tomato. Among the different spacing, the widest spacing of 60 cm x 60 cm recorded the highest fruit yield plant-1. The interaction effects were significant with the highest yield in the combination where the individual effects of nutrient levels as well as spacing were significantly the highest, viz., N4S1. The fruit weight was also the highest in the same treatments and the crop duration the modest. The lowest fruit weight and the shortest duration of crop was observed in N3. The widest spaced plants produced the highest fruit weight and the combination involving POP recommendation and the widest spacing (N4S1) again produced the heaviest fruits. The fruit quality and appearance was also found the best in N1 and N4 when compared to other two levels. Spacing had no effect on the quality characters while the interaction between nutrient levels and spacing had significant effect on lycopene and TSS content with N1S1 giving the highest values for them. The dry weight of plants was found the highest in N1 and in the widest spacing (S1) and among the interaction the same combination produced the highest plant dry weight (N1S1). The nutrient uptake especially N and P was found the highest in N4 and K in N1. In closer planting the nutrient uptake was the highest consequent to the increase in population. The organic carbon and available nutrient status after the experiment was the highest in N1. The effect of nutrient levels and spacing were significant in benefit-cost ratio at the normal market price as well as the premium prices of the produce. The POP recommendation (N4) with an integrated nutrient approach with organic and inorganic sources fetched the highest B:C ratio. Similarly for planting distances, it was found that tomato cultivation become remunerative in terms of B:C ratio only when the plants were spaced at a closer distance than wider spacing. Inorder to study the residual effect of organic nutrition, a crop of amaranthus (Amaranthus tricolor) was raised after tomato and the biometric characters of the residual crop studied were influenced by nutrient levels with the highest values in N4 (control) and the lowest in N3. The marketable yield of amaranthus was also found the highest in N4 (control). Similarly the economics of amaranthus cultivation revealed the significance of N4 and S3 in producing the highest B:C ratio. The combination of N4 and S3 also recorded the highest B:C ratio in amaranthus. The uptake of nutrients especially N and K was found the highest in N4 and N1. Though spacing had no significant role in the uptake of nutrients, the combination of nutrient levels and spacing had significant influence and the highest uptake was observed in N4S3. The combined B:C ratio of tomato-amaranthus sequence was determined at the premium price of tomato plus the market price of amaranthus by assuming a 20 % hike for the organic produce in the market. The effect of nutrient levels and spacing were significant with N4 giving the highest B:C ratio and N3 the lowest. The closely spaced plants (S3) recorded the highest B:C ratio and the widest spaced plants (S1), the lowest. The interaction effect was significant with the highest B:C ratio in N4S3 and the lowest in N3S1. Among the organic treatments N1 was found the best with a combined B:C ratio of 1.38 followed by N2 (1.00) and the lowest in N3 (0.78). Among the organic combination with spacing it was in N1S3 the highest B:C ratio found (1.42) followed by N1S2 (1.36) and N1S1 (1.35).
Open Access
Production technology for organic sweet potato
(Department of Agronomy, College of Agriculture, Vellayani, 2011) Dhanya, T; KAU; Pushpakumari, R
Kerala the ‘Land of coconut’ occupies first position in area and production of coconut in India but the productivity is below the national average. This is because of unproductive and senile palms, lack of adaptation of recommended cultivation practises and serious incidence of pests and diseases. The root (wilt), an endemic disease of Kerala causes an annual loss of 968 million nuts. Recently another type of yellowing characterised by mid whorl yellowing shedding of immature nuts and drying of inflorescence without showing characteristic ribbing symptom is rapidly spreading in many parts of Kerala. There is no research report available in this emerging problem in the coconut growing tracts of Kerala. Since there is rampant spreading of yellowing to other coconut cultivated areas causing a serious reduction in nut yield, this problem demands immediate attention. Hence an experiment was conducted in the Department of Plant Physiology, College of Agriculture, Vellyani to generate the basic information on the causative agents and on the changes of physiological, molecular and anatomical realms of coconut affected by mid whorl yellowing A wide variation was observed in the physiological parameters like total pigments, relative water content, carbohydrate fractions, proteins, phenols and antioxidants betweenpalms with yellowing and control palms. The palms with yellowing showed a significant reduction in the total chlorophyll, chlorophyll a, chlorophyll b and carotenoid content when compared to the healthy palm. Relative water content was lower for all the palms with yellowing compared to the control palm and the healthy palms were maintaining a better water status and membrane integrity. All the selected palms with yellowing recorded an accumulation of reducing sugars compared to the healthy palms. The trend was similar for starch content except for palms with general yellowing. The control palms recorded maximum protein content compared to other palms with yellowing. A significant increase in the phenolic compounds was observed in palms with yellowing compared to the healthy palms. This results point to an activated defense system. The 14th leaf starting from the first fully opened one is the most widely used leaf for nutrient analysis as recommended by the IRHO. (Fremond et al., 1966).The 14th leaf data from the control palms and palms with different types of yellowing were analysed. The data showed that there were significant reductions in the levels of major nutrient nitrogen, phosphorus and also in the levels of magnesium and the micronutrient manganese in case of palms showing mid whorl yellowing compared to the control palm. But significantly higher levels of accumulation were found in case of potassium, calcium, iron and copper. These variations in the nutrient levels can have an influence on symptom development in coconut palms. The maximum yield was recorded for the control palm. Chlorophyll degradation and loss of structural integrity were evident from the anatomical studies of leaf tissues in case of palms with yellowing. Vascular browning which extended to the cortex and the vascular disintegration in the roots of affected palms were seen on anatomical analyses. A pure quality DNA was obtained by modified CTAB DNA isolation protocol. Molecular analyses using nested PCR showed that with the phytoplasma specific universal primers P1/P7-R16F2n/R16R2 provided an amplicon ) in the positive control and palms with inner and middle whorl yellowing and the primers R16mF2 /R16mR1 -R16F2n/ R16R2 provided an amplicon for the positive control and palms with inner, middle and general yellowing. The root (wilt) phytoplasma specific semi- nested primers IF7/7R3- IF7/7R2 provided an amplicon of 493 bp only for the positive control and no amplification was seen in any of the selected palms. The control palm and the palms affected with outer whorl yellowing provided no amplification at all for any of the primers tested. Amplification of phytoplasma specific universal primers in palms with mid whorl yellowing indicates that phytoplasma has got a role in development of the specific symptom. This demands immediate attention and extensive studies on the etiology, changes in biochemical profile, anatomy etc. Salient Findings Amplification of phytoplasma specific universal primers in palms with mid whorl yellowing indicates that phytoplasma has got a role in development of the mid whorl yellowing symptom. But in case of the root (wilt) phytoplasma specific primers, there was no amplification in palms with mid whorl yellowing. This suggests that the mid whorl yellowing of coconut palm which is an emerging problem in Kerala may not be associated with the root (wilt) disease. The results of biochemical and physiological analyses of the selected palms clearly indicate an altered primary metabolism, source-sink relation and a complexity in the nutriophysiology. These altered conditions can act as predisposing factors for the development of specific symptoms. The anatomical analyses showed damages of roots in the palms with mid whorl yellowing. They will have internal browning of vascular elements, extending into the cortex and also disintegration of vascular elements. Future line of work Detailed analysis of nutriophysiology, source-sink relation and hormonal profile. Studies on soil factors like nutrient level and water status. Extension of anatomical studies to different type of tissues. Extension of molecular studies into identification of specific phytoplasmal strains associated with mid whorl yellowing of coconut palms. Development of management strategy for the improvement of the field performance and productivity of coconut palms with mid whorl yellowing.
Open Access
Integrated weed management under system of rice intensification (SRI)
(Department of Agronomy, College of Horticulture, Vellanikkara, 2011) Musthafa, Kunnathadi; KAU; Abraham, C T
An experiment was conducted to assess the performance of system of rice intensification (SRI) vis-à-vis conventional system with special emphasis on weed problems under SRI and to develop an economic weed management strategy. Aiming at reducing drudgery while using manual cono weeder, it was also envisaged to develop the prototype of a self propelled cono weeder. The field studies laid out in randomized block design with 16 treatments in three replications were conducted at RARS, Pattambi in Palakkad district and in farmers’ fields at Alappad Kole in Thrissur district, during the Mundakan seasons of 2007 and 2008. The soil at Pattambi was lateritic sandy clay loam with pH 4.96 and medium fertility, and that at Alappad Kole was clayey in texture with pH 5.0 and of high fertility. At both locations, the density and dry weight of weeds at 45 and 60 days after transplanting (DAT) were higher in all the SRI treatments especially when weed control was done through repeated cono weeding. At Pattambi, weed density and weed dry weight were the lowest in conventional system with post emergence herbicides, which recorded lower nutrient removal by the weeds and the lowest weed index and also higher gross return, net return and B:C ratio. The weed density and dry weight in the SRI fields were the lowest with pre emergence herbicide followed by hand weeding at 30 DAT, but the use of post emergence herbicides showed higher B:C ratio. At Alappad Kole, the weed density and dry weight, both at 45 and 60 DAT, were the lowest in conventional system with cono weeding at 10 DAT followed by post emergence herbicides. Cono weeding followed by hand weeding, pre emergence herbicides followed by hand weeding as well as the use of post emergence herbicides were also equally effective in controlling the weeds 233 in the conventional system, and were on par in the B:C ratios. In the SRI plots cono weeding at 10 DAT followed by post emergence herbicides recorded the lowest weed density and dry weight, however, use of post emergence herbicides recorded the highest net return and B:C ratio among the SRI treatments. Thus, considering the acute shortage and high wages for the labourers in Kerala, weed management through post emergence herbicides will be the preferable option for the farmers in both conventional and SRI systems of rice cultivation. Comparison between the two systems of rice cultivation at two different rice growing ecosystems showed that SRI improved the performance of individual hills through higher number of tillers hill-1, root length and root dry weight hill-1. On the other hand, the tiller number, dry matter production, root dry weight and productive tillers per unit area were higher in the conventional treatments. Owing to higher number of productive tillers per unit area the grain yield of conventional treatments was significantly higher than that of the typical SRI. At Pattambi, conventional system with post emergence herbicides recorded higher number of productive tillers m-2, panicle length, number of filled grains panicle-1, 1000 grain weight and grain yield (2877 kg ha-1), which was 33 per cent higher than the grain yield in the typical SRI. This treatment also recorded significantly higher B:C ratio (1.27) compared to that (0.91) of the typical SRI. However, the highest straw yield (2510 kg ha-1) at Pattambi was observed in ‘SRI with cono weeding at 10 DAT followed by post emergence herbicides’, which was on par with the typical SRI treatment. At Alappad Kole, higher number of productive tillers m-2, more filled grain percentage, highest 1000 grain weight, highest grain yield (6073 kg ha-1) and highest straw yield (5109 kg ha-1) were recorded by conventional system with cono weeding followed by hand weeding, which showed an increase of 93 per 234 cent in grain yield, with an additional yield of 2934 kg ha-1, and 109 per cent in straw yield over the typical SRI and recorded the highest gross return, net return and B:C ratio (2.46). Thus, the study showed the superiority of conventional system of rice cultivation at a spacing of 20 cm x 10 cm over the SRI system at a spacing of 30 cm x 30 cm at both the two different rice growing ecosystems studied viz., the sandy loam soils at Pattambi and the clayey soils at Alappad Kole. Prototype of the self propelled cono weeder was developed and field tested. It works satisfactorily in a single forward pass, and covers an area of 0.1 ha h-1. The field study showed that the self propelled cono weeder is effective for inter row weeding in rice, however, further refinement is needed to improve its weeding efficiency.
Open Access
Rhizosphere management for enhancing root productivity and oil yield in vetiver (Vetiveria zizanioides (L.) Nash.
(Department of Agronomy, College of Agriculture, Vellayani, 2011) Shimi, G J; KAU; Anilkumar, A S
Vetiver is the only grass cultivated specifically for its root essential oil, a complex mixture of sesquiterpene alcohols and hydrocarbons, used extensively in perfumery and cosmetics. The World Bank has promoted the Vetiver System since the 1980s for various applications such as soil erosion and sediment control, water conservation, landslip and riverbank stabilization and recently for pollution control. However, cost effective techniques for increasing root production in the humid tropics are lacking. The present investigation was carried out at the College of Agriculture, Vellayani to study the effect of planting methods, subsurface drip fertigation and combined application of bioinoculants on root and oil yield in vetiver (Vetiveria zizanioides). The technical programme consisted of combinations of three planting methods, viz, P1 – Planting in coconut husk mulched trenches, P2 – Planting in coconut husk lined trenches and P3 – Planting on the ridges, two levels of fertigation, viz, F1 – Subsurface drip fertigation and F2 - No fertigation; and two bioinoculants, viz, B1 - Application of bioinoculants and B2 - No bioinoculants. The trial in Factorial RBD was conducted during 2010-11. Planting methods, fertigation levels and application of bioinoculants influenced various growth characters of vetiver, viz., plant height, number of leaves and tiller production at various stages of growth. In general, planting in coconut husk lined trenches resulted in better performance. Installation of sub surface drip fertigation system and application of bioinoculants also encouraged vegetative growth. The effect of the above treatments on number, length, spread, volume and weight of vetiver roots were found to be remarkable at certain stages of growth. In general, planting in coconut husk lined trenches was found to improve all the root parameters studied when compared to ridge planting. The effect of bioinoculant application was also conspicuous in improving root growth compared to control (no inoculation). Planting vetiver slips treated with bioinoculants in coconut husk lined trenches under sub surface drip fertigation 111 system provided a favourable situation for root elongation during the early phase of crop establishment. Planting methods, fertigation levels and application of bioinoculants had no significant effect on any of the physiological parameters, viz, canopy temperature, relative leaf water content and osmotic potential studied. Significant influence of planting methods on chlorophyll a and total chlorophyll were observed. Planting on ridges (P3) which was on par with planting in coconut husk lined trenches (P2) showed significantly higher contents of chlorophyll a and total chlorophyll. Leaf dry matter production at all stages and root dry matter at certain stages were found to be significantly influenced by the main effects of treatments. Similar to biometric characters, leaf and root dry matter production were found highest when vetiver was planted in coconut husk lined trenches. Sub surface drip fertigation had a positive and significant effect in enhancing leaf and root dry matter production. The effect of bioinoculants was also positive and significant in improving the above parameters when compared to control. Among the different planting methods, planting in coconut husk lined trenches registered the highest value of soil moisture content before irrigation which was closely followed by planting in coconut husk mulched trenches. The effect of sub surface drip fertigation in influencing soil moisture content before and after irrigation was remarkable. However, application of bioinoculants was not found to significantly influence soil moisture contents. Planting in coconut husk lined trenches (P2), installation of sub surface fertigation system and application of bioinoculants enhanced root and oil yield. Economic analysis of the system also proved the superiority of planting vetiver in coconut husk lined trenches (P2), installation of sub surface drip fertigation system and application of bioinoculants in improving gross and net income. APPEND
Open Access
Input optimization for medicinal rice (Oryza sativa L.) cv. Njavara.
(Department of Agronomy, College of Agriculture, Vellayani, 2011) Sriramkumar, N; KAU; Geethakumari, V L
The investigation entitled “Input optimization for medicinal rice (Oryza sativa L.) cv. Njavara” was conducted at Instructional Farm, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, during the summer seasons of 2007 and 2008 (January to April) to standardize an ideal nutrient schedule under two moisture regimes for sustaining Njavara production in lowlands, to investigate the soil physical, chemical and biological properties as influenced by regimes and sources of nutrients and to work out the economics of Njavara cultivation. Both the experiments (submerged and saturated situations) were laid out in randomised block design with ten treatments each and three replications. The treatments comprised four nutrient regimes viz., N1 - 30:15:15, N2 - 30:30:30, N3 - 40:20:20 and N4 - 40:40:40 kg NPK ha-1, two nutrient sources viz., organic nutrient source (S1) and integrated nutrient source (S2) and two controls viz., absolute control (no nutrient was applied) (C1) and POP for local rice variety (C2). Growth components like plant height, leaf number plant-1, leaf area index (LAI), number of tillers m-2, culm strength and flag leaf area, yield and yield attributes like number of productive tillers m-2, panicle length, number of grains panicle-1, number of filled grains panicle-1, 1000 grain weight, harvest index, sterility percentage, dry matter partitioning, paddy grain ratio and grain husk ratio were recorded. Leaf chlorophyll content was also estimated. Uptake of nutrients (N, P, K, S, Fe, Mn and Zn) and economics of cultivation were computed. Biochemical components of grains such as total, free and sulphur containing amino acids, phenols, starch, amylose, amylopectin and protein content were estimated. Data on weed biomass, weed flora and crop duration were also recorded. Soil enzymes (urease, phosphatase and dehydrogenase), soil microbial population (bacteria, fungi and actinomycetes population) and soil fertility status (available nitrogen, phosphorus, potassium, sulphur, iron, zinc and manganese) were assessed before and after the crop. Effect of nutrient regimes Effect of nutrient regimes on all growth parameters was significant. Growth parameters like plant height, leaf number plant-1, leaf area index (LAI), number of tillers m-2, culm strength and flag leaf area were significantly higher in N2. N2 recorded leaf chlorophyll content which was significantly higher than N3 and N1 and was on par with N4. All yield attributes except 1000 grain weight were significantly influenced by nutrient regimes resulting in significant variation in the crop yield (grain and straw). Maximum grain yield was recorded in N2 (30:30:30 kg NPK ha-1) (2.78 and 2.66 t ha-1) which was on par with N4 (40:40:40 kg NPK ha-1) (2.67 and 2.58 t ha-1) and was significantly superior to N1 and N3 under submerged and saturated situations respectively. Duration of the crop did not show significant variation due to nutrient regimes. Total amino acid and protein content of grain were significantly influenced by nutrient regimes and were maximum in N2. Nutrient regimes significantly influenced N, P and K uptake. Uptake of N, P and K in N2 was significantly higher than that in the other three nutrient regimes. Nutrient regimes did not significantly influence uptake of S, Fe, Mn and Zn. Results of the study also revealed that Echinochloa colona (L.) Link, Isachne miliacea Roth ex Roem. et Schult; Cyperus iria L., Cyperus difformis L. Fimbristylis miliacea (L.) Vahl.; Marsilea quadrifoliata Linn., Monochoria vaginalis (Burm. f.) Presl. ex Kunth and Ludwigia perennis L were the most predominant weed species in the experimental field under both situations. Weed biomass at 20 and 40 DAS were not significantly influenced by nutrient regimes during both the years of experimentation. Nutrient regimes showed significant influence on available nitrogen, phosphorus and potassium status of the soil after the investigation. Available sulphur, iron, zinc and manganese status of the soil after the experiment revealed non-significant effect of nutrient regimes in both the years of study. Among the soil enzymes, urease activity was influenced significantly by the nutrient regimes and it was in the order N4 > N3 > N2 > N1. Bacterial population was influenced significantly by the nutrient regimes and it was in the order N4 > N3 > N2 > N1. Effect of nutrient sources Nutrient sources had significant influence on all the growth characters, yield attributing characters like number of grains panicle-1, number of filled grains panicle-1, harvest index as well as crop yield (grain and straw). Highest number of grains panicle-1, filled grains panicle-1 and crop yield (grain and straw) were realized in integrated nutrient source and they were significantly higher than that realized from organic source. Duration of crop did not differ significantly between the nutrient sources. Integrated nutrient source registered significantly higher nitrate reductase activity and root weight compared to organic source. Biochemical components such as total, free and sulphur containing amino acids, phenols, starch, amylose, amylopectin and protein content of grain did not differ significantly between nutrient sources. Highest uptake of N, P and K was in integrated nutrient source. Sources of nutrients did not influence uptake of S, Fe, Mn and Zn during both the years of experimentation. Weed biomass under different nutrient sources at both 20 DAS and 40 DAS differed significantly from one another. Weed biomass during both stages and both the years of experimentation was more in organic source compared to integrated nutrient source. Highest weed biomass was recorded in absolute control at both stages during both the years. Available nitrogen, available phosphorus and available potassium status of the soil after the experiment in the plots receiving integrated nutrient source and organic nutrient source differed significantly from each other. Available N, P and K status of the soil were higher in integrated nutrient source. Organic carbon, available sulphur, iron, zinc and manganese status of the soil after the experiment were not significantly influenced by nutrient sources. Urease activity and bacterial population in the soil were influenced significantly by nutrient sources. Highest activity of urease and bacterial population in the soil were recorded in organic source compared to integrated nutrient source. Phosphatase and dehydrogenase activity as well as fungal and actinomycetes population in the soil were not influenced by nutrient sources. Economics of crop production Gross income, net income and BCR were highest in N2S2. Application of FYM @ 5 t ha-1 along with 30:30:30 kg NPK ha-1 (50 % N as organic + 50 % N as chemical fertilizer) (N2S2) recorded a net profit of Rs 57,586 ha-1 and Rs 53,546 ha-1 under submerged and saturated situations respectively. The lowest gross income, net income and BCR were recorded in N1S1 (FYM @ 5 t ha-1 along with 30:15:15 kg NPK ha-1 as organic source). The ideal nutrient schedule for sustaining Njavara production in lowlands under both submerged and saturated situations is N2S2 - FYM @ 5 t ha-1 + 30:30:30 kg NPK ha-1 (50 % N as organic + 50 % N as chemical fertilizer). This nutrient system realised highest grain yield, straw yield and net income.
Open Access
Floristic diversity, autecology and competitive behaviour of weed flora in wetland rice ecosystem
(Department of Agronomy, College of Agriculture, Vellayani, 2010) Sajith Babu, D; KAU; Sansamma George
Floristic diversity, autecology and competitive behaviour of weed flora in the wetland rice ecosystem were studied by conducting a field survey and two field experiments. The field survey was conducted during the first and second crop seasons of 2003 in the rice fields of 30 panchayaths in Thiruvananthapuram district having more than 50 hectares of net sown area, covering all the four thaluks of the district. Weed flora was surveyed from both cultivated and fallow fields. The design adopted for conducting the floristic survey was Stratified Multistage Random Sampling and the methodology was Census Quadrate Method. The field experiments were conducted during the first crop seasons of 2003 and 2004 at College of Agriculture, Vellayani. The design adopted was Strip plot. The treatments included four levels of nutrient management and three levels of crop spacing and the number of replications was five. Part III of the investigation was an autecological study wherein the growth and development pattern of two of the major weed flora observed in the experimental area was studied by keeping an area of 1.2 X 4.2 m2 on the same side of all the plots in Part II. Perusal of the results of the field survey indicated that substantial diversity of weed flora existed in the wetland rice ecosystem in Thiruvananthapuram district of Kerala. In the cultivated rice fields, there were 46 weed specii during the first crop season and 49 species during the second crop season. In the rice fallows during the first crop season there were 43 specii while during the second crop season there were 54 specii. In the cultivated fields during both seasons, the most prominent species among the different classes of weeds (grasses, sedges and broad leaved weeds) were Isachne miliacea Roth ex Roem et Schult, Cyperus iria L. and Monochoria vaginalis (Burm.f.) Presl. Ex Kunth respectively. Isachne miliacea Roth ex Roem et Schult was the dominant grass weed in the fallows as well. However the dominant sedge weed in the fallows was Cyperus distans L.f. during the first crop season while it was Fimbristylis miliacea. during the second crop season. Monochoria vaginalis (Burm.f.) Presl. Ex Kunth and Ludwigia perennis topped the list of broad leaved weeds in the rice fallows during first and second crop seasons respectively. Results of the field experiment showed that weed growth in the rice field was influenced significantly by the sources and levels of nutrients as well as by crop spacing. During both the years at 20 and 40 DAT the weed density and dry weight were the lowest when the rice crop was treated with NPK @ 90:45:45 kg ha-1 applied with 25 per cent N as organic (N2) while at 60 DAT enhanced nutrient level (NPK @ 112.5:56:25:56.25 kg ha-1) applied with 25 per cent N as organic (N4) recorded the lowest value. During both the years, at all growth stages the weed density and dry weight were the lowest under the closer spacing of 15 X 15 cm (P1) The grain and straw yield were maximum under NPK @ 112.5:56:25:56.25 kg ha-1 applied with 25 per cent N as organic in combination with widest spacing (n4p3). Dead heart occurrence was minimum under the widest crop spacing The net income and Benefit : Cost ratio were the highest when rice crop was treated with 125 per cent of the recommended NPK with 25 per cent organic substitution in combination with widest spacing (n4p3) Autecological studies showed that the growth and development of Isachne miliacea Roth ex Roem et Schult. was significantly influenced by the management practices for the associated rice crop. The higher dose of NPK applied as chemical fertilizers only (N3) along with widest spacing (P3) stimulated all the vegetative parameters (shoot / root length and plant spread) of the weed. During both the years plants growing in rice fields treated with recommended dose of NPK with 25 per cent organic substitution (N2) and rice crop planted at wider spacing (P3) recorded delayed flowering but produced more seeds per panicle The root and shoot length of Cyperus iria L growing in rice fields treated with 100 per cent recommended NPK as chemical fertilizers (N1) with minimum spacing (P1) recorded the maximum value during the both years. Delayed flowering of the sedge was noticed under N2. The number of seeds produced per plant was significantly high under N4 and P3. The general trend was that addition of organic manures in rice delayed flowering but increased seed production in the associated sedge weed From the studies it may be concluded that by altering nutrient management and adjusting the plant population, the competitive ability and productivity of rice crop can be improved substantially. Though, closer spacing of 15 X 15 cm significantly reduced the density and dry weight of weeds, the wider spacing of 20 X 20 cm in conjunction with enhanced fertilizer dose of 112.5:56:25:56.25 kg NPK ha-1 applied with 25 per cent N as organic manures significantly enhanced the rice grain and straw yield. The treatment also resulted in significant enhancement in net income and B:C ratio in medium duration variety Aiswarya in first crop season.
Open Access
Management of greater club rush (scirpus grossus L.f) in wetland rice ecosystem
(Department of Agronomy, College of Agriculture, Vellayani, 2011) Sreethu, G S; KAU; Sansamma, George
An investigation entitled“ Management of greater club rush (Scirpus grossus L.f) in wetland rice ecosystem’’was undertaken in a wetland rice ecosystem heavily infested with the weed. The study was taken up during February 2010 to January 2011. The main objectives of the experiment were to develop a management strategy for recovering the wetland rice ecosystem invaded by greater club rush, economical analysis of rice cultivation in the land recovered from the invaded weed and study of the weed biology. Laboratory studies conducted at College of Agriculture, Vellayani, were also included to achieve the objectives envisaged. The field experiment on weed management (part I) was laid out in Randomised Block Design with nine treatments and three replications. The treatments included farmer’s practice of tillage, application of lime at two different doses after tillage and application of glyphosate and 2, 4 – D alone and in combination on weed re-growth with and without tillage. Before applying the treatments, the thick growing weed was given an initial mowing. The laboratory studies were done to analyse the herbicide residue in the treated plots and to study the effect of the applied herbicides on the soil microbial population. The treatment adjudged as the most efficient was verified further in a larger plot, by comparing it with the farmer’s practice of weed management to study the economics of rice cultivation in the land recovered from the invasive weed (part II). The biology of greater club rush was also studied simultaneously (part III). The results of the weed management study indicated that all the herbicidal treatments were significantly superior to farmer’s practice of tillage in reducing the weed dry weight. Weed control efficiency was found to be 100 percent throughout the study, when the thick infestation was mowed once and treated with a combination of (glyphosate @1kg ai ha-1 + 2,4-D @ 2 kg ai ha-1) Tillage + glyphosate @1kg ai ha-1 + 2,4-D @ 2 kg ai ha-1 was also effective in controlling the weed, but fragments of root system was found remaining in the soil even after nine months; as a possible source of reinfestation. However, application of lime as a means of controlling greater club rush was found to have no effect on the weed growth. Considering all factors, T7 (glyphosate @1kg ai ha-1 + 2,4-D @ 2 kg ai ha-1) was adjudged as the best treatment for testing further in the farmer’s field (part II ). There was substantial increase in the floristic diversity after the experiment in herbicide treated fields which were completely cleared of greater club rush within 45 days of herbicide application. The residue analysis of the soil collected on the next day of herbicide application revealed that the residue was below detectable limit in the case of both 2, 4 – D and glyphosate, alone as well as in combination. The results on soil microbial population indicated that the soil treated with any of the herbicides had a much higher microbial population than the untreated plots. The cost worked out for the management of the thick infestation of greater club rush was prohibitively high in all the treatments. Economic analysis of rice cultivation in the land recovered from the invasive weed indicated that the grain and straw yield in the treated plot was substantially higher than that from the non treated plots. When the economics was worked out inclusive of the cost of land recovery through eradication of greater club rush, the net profit from rice cultivation was not very high. But the important indication was that the farmers suffered great loss when they followed the present practice of mowing followed by tillage. The observations on the weed biology indicated that in greater club rush, propagation was exclusively through vegetative means. The nutrient composition of the weed was comparable to that of rice plant. Due to its very high biomass production, the nutrient uptake of greater club rush was much higher than that of rice crop.

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