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Open Access
Ecophysiology and management of Isachne in rice fields of Onattukara
(Department of Agronomy, College of Horticulture, Vellanikkara, 1996) Abraham, Varughese; KAU; Tajuddin, E
Isachne miliacea Roth is the most dominant weed in the 28,000 ha of low land rice fields of the coastal sandy Onattukara region, situated in Kollam and Alapuzha districts of Kerala. A serious of investigations were undertaken at Rice Research Station, Kayamkulam, during 1991 to 1994 with the objective to identify the major weeds in the rice ecosystem and to bring out the ecophysiology of 1. Miliacea and to find out a suitable weed management strategy for the rice based cropping system of Onattukara. Isachne miliacea was found to be the dominant weed in rice during Kharif and Rabi seasons. The weed seeds germinate in April – May, attains its peak vegetative growth in July and flowers in October. The seeds mature in November and the plants dry off in January with the onset of summer. The weed is propagated by seeds and stem cuttings. Germination of seeds can be prevented by submerging the seeds in the area in water even to a depth of one centimetre. The forcing of the stem cuttings of 1. Miliacea to a depth of five centimetre below the soil surface or maintaining a submergence for more than five centimetre can effectively check the vegetative multiplication of the weed. Seeds attained physiological maturity in November and remained dormant upto March. Seeds of the season that remain on the surface germinate fully in April – May with the pre – monsoon showers while the buried seeds remain dormant. Burying the seeds to more than five centimetre depth and water stagnation in July to November induced secondary dormancy. Viability of the seeds was lost faster at shallow depth of burial. Crop weed competition studies were conducted in Kharif and Rabi for two years with different densities of 1. Miliacea. Weed competition was severe in dry dibbled Kharif compared to wet transplanted Rabi. Even a small density of five 1. Miliacea plants per square metre produced appreciable biomass and reduced the DMP of rice substantially. Integrated weed management study was conducted in Kharif and Rabi for two years in a split – plot design in three randomised blocks. Kharif season treatments formed the main plots for Rabi trial. In Kharif five pre – emergence herbicides were compared with local practice. Local practice of hoeing on 15 DAS and HW twice on 25 and 40 DAS gave maximum grain yield. Application of oxyfluorfen 0.1 kg ha-1 followed by HW on 30 DAS was on par with local practice and ranked second. The performance of other herbicides anilofos 0.40 kg, butachlor 1.25 kg and thiobencarb 1.25 kg per hectare were also satisfactory when followed by one HW on 30 DAS. Pretilachlor 0.50 kg ha-1 was phytotoxic to rice. The tested herbicides effectively controlled 1. miliacea upto harvest of rice compared to local practice. During Rabi the effect of pre-plant spray of glyphosate and hand weedings were compared. Among the treatments a pre – plant spray of glyphosate after harvest of Kharif controlled 1. miliacea best and gave maximum rice yield in Rabi season. Kharif treatments did not show any significant influence on yield of rice during Rabi. From the study it could be concluded that pre – emergence spray of oxyfluorfen 0.1 kg ha-1 followed by one HW on DAS in Kharif and pre – plant application of glyphosate 0.75 kg ha-1 on residual weeds immediately after the harvest of the Kharif crop gave efficient weed control and economic yield of rice in the rice based cropping system involving rice – rice – fallow of Onattukara region.
Open Access
Nutrient management with biofertilizers in a fodder maize-cowpea intercropping system
(Department of Agronomy, College of Agriculture, Vellayani, 1996) Kavitha, P K; KAU; Raghavan Pillai, K
An experiment was conducted in the Instructional farm attached to the College of Agriculture, Vellayani during the Kharif season in 1994. The object was to study the effect of different bioinoculants {Azospirillum, Rhizobium, Vesicular arbuscular mycorrhiza (VAM) as well as different levels of nutrients ie control, 25, 50, 75 and 100 percent of the recommended dose of fertilizer and their interaction on increasing the forage production of maize - cowpea intercropping system. The height of maize plant, number of leaves, and leaf area index were maximum for the treatment, Azospirilllum - maize + Rhizobium - cowpea but the maximum leaf-stem ratio was observed for Azospirillum- maize + VAM - cowpea. In cowpea, all the growth characters were maximum for the treatment, VAM - maize + Rhizobium-cowpea. It was also seen that fertilizer level above 50 percent didn't produce any significant increase in these characters. In maize, highest root length was observed for Azospirillum - maize + Rhizobium - cowpea treated plants and highest root volume for, Azospirillum - maize + VAM - cowpea treated plants. Maximum nodulation in cowpea was observed for the treatment, VAM -maize +Rhizobium- cowpea and maximum root length for Azospirillum – maize + VAM – cowpea. Mycorrhizal colonization percentage was found to be higher in the roots of inoculated plants for both crops. All these character were found to be maximum under no fertilizer application. . Maximum green matter and drymatter yield of maize occurred for the treatment, Azospirillum – maize + VAM - cowpea and for cowpea, the treatment VAM –maize +Rhizobium – cowpea. It was also noted that 50 percent of the recommended dose of fertilizer was enough for producing maximum yield. The treatment Azospirillum – maize + VAM cowpea produced maximum uptake of nitrogen in maize, phosphorus in cowpea and potassium, calcium and magnesium uptake in both the crops. The treatment VAM –maize + Rhizobium – cowpea produced the maximum uptake of phosphorus in maize and nitrogen in cowpea. The uptake of nutrients do not differ significantly after 50 percent of recommended dose of fertilizer. In maize, crude protein yield and crude fibre yield were maximum for the treatment, Azospirillum – maize + VAM- cowpea under high levels of fertilizer. In cowpea, the treatment VAM – maize + Rhizobium – cowpea at high levels of fertilizer produced maximum value. The available nitrogen, phosphorus, potassium, calcium and magnesium status of the soil varied significantly due to the interaction between biofertilizer and chemical fertilizers. The treatment combination, VAM – maize + Rhizobium – cowpea + 50 percent of the recommended dose registered the highest net profit of Rs.8110.00 and Benefit – cost ratio of 1.502. The treatment combination, VAM- MAIZE + Rhizobium-cowpea + 50 percent of the recommended dose can be given as the final recommendation in fodder maize-cowpea intercropping system.
Open Access
Effect of biofertilizers on N and P economy in palmarosa(cymbopogon martinii)
(Department of Agronomy, College of Horticulture, Vellanikkara, 1996) Regimol, Thomas; KAU; Lalitha Bai, E K
An investigation was undertaken at the College of Horticulture, Kerala Agricultural University, Vellanikkara, during 1994-’95 to study the effect of biofertilizers on N and P economy in palmarosa (Cymbopogon martini stapf. var. motia). The main objective of the study was to assess the possibility of using biofertilizers so as to replace or minimise the expensive synthetic nitrogen fertilizers for palmarosa. The study also aimed to find out the effect of phosphorus solubilising bacteria (Bacillus megatherium var.phosphaticum) in increasing the availability of fixed soil phosphorus, the effect of combination of chemical and biofertilizers on the growth and yield of palmarosa and to work out the N and P economy due to the integration of chemical and biofertilizers. The experiment was carried out using the palmarosa selection ODP-2. The salient findings are abstracted below: The application of chemical fertilizers increased the available N, P and K contents in soil after different harvests, resulted in increased nutrient uptake and thus improved the growth and yield of palmarosa. The oil yield obtained with the application of 20 kg ha -1 each of N and P2O5 was significantly superior to that in the control plot. The different biofertilizer levels were compared with regard to their effect on palmarosa and it was observed that the combined inoculation of Azospirillum and PSB was the best in increasing the available N, P and K contents in soil and the nutrient uptake by the crop. Hence this particular treatment resulted in the highest oil yield which was significantly superior to that in the uninoculated control. The interaction effect of chemical X biofertilizers showed that the oil yield over a period of one year obtained with the application of 20 kg ha-1 each of N and P2O5 was on par with that obtained with the applications of either Azotobacter alone or Azospirillum alone and also the combined inoculation of Azospirillum and PSB. Thus the biofertilizers Azotobacter alone, Azospirillum alone and the combined inoculation of Azospirillum and PSB could substitute chemical fertilizers to the level of 20 kg ha-1 each of N and P2O5. The data again showed that the combined application of chemical and biofertilizers ie, N and P2O5 each at 20 kg ha -1 along with Azospirillum plus PSB resulted in comparable total oil yield, total returns, net returns and benefit-cost ratio as that obtained with the application of N40 P40 along with Azospirillum plus PSB which recorded the highest value.
Open Access
Weed management in cardamom plantations
(Department of Agronomy, College of Horticulture, Vellanikkara, 1996) Sudheesh, M V; KAU; Abraham, C T
A study was conducted during 1995 -96 to develop weed management practices for cardmom at Cardamom Research Station, Pampadumpara under Kerala Agricultural university. A trial was also conducted to evaluate major herbicides in cardamom plantions. Ten major weeds Ageratum conyzoides,Bidens pilosa, Crassocephalam crapioides, synedrella nodiflora, Paspalam conjugatum, Scoporia dulcis, Drymaria cordata, Erigeron Canadensis, Spilanthes calva and Eleusine indica were identified. Survey indicated the dominance of Asteraceae and Gramineae in cardamom tracts of Idukki district. Maximum germination percentage was observed in Bidens pilosa. All the weeds except Bidens pilosa, Scoparia dulcis and Spilanthes calva flowered in May. Rest of the weeds flowered by July and set seeds by the end of September. Maximum seed production and lowest 1000 seed weight was recorded by Scoparia dulcis. Nutrient study revealed the deversion of nutrients to flower heads after flower production. The results of the yield trial to compare efficiency of herbicides revealed the use of paraquat 0.4 kg/ha (bimonthly) or glyphosate 0.8 kg/ha is superior in terms of reducing the weed count, weed dry matter and nutrient removal by weeds from the experimental plots. Except tiller production all the characters, plant height (cm), per cent flowering (%) and yield (Kg/ha) did not differ significantly with treatments. Phytotoxic study revealed paraquat as less toxic than glyphosate. In combination with paraquat, atrazine and diuron residues persisted upto 60 days in the experimental field. More than rupees 6000 can be saved by adopting chemical methods instead of hand weeding.
Open Access
Yield maximisation of direct sown rice under puddled condition
(Department of Agronomy, College of Agriculture, Vellayani, 1996) Sajith Babu, D; KAU; John, P S
An experiment entitled “yield maximisation of direct sown rice under puddled condition” was conducted at Rice Research Station, Moncompu, Kerala Agricultural University, during the additional crop season (Kharif) of 1995 to study the effect of combined use of organic manures and inorganic fertilizers under different plant population for enhancing rice yield in the lowlands of Kuttanad using the variety Pavizham. Factorial combinations of two levels each of organic manure and seed rate and three levels of chemical fertilizers were tried in Randomised Block Design with three replications. Organic manure addition @ 10 t ha -1 was found to have pronounced effect on various growth and yield attributing characters of rice when applied alone and/or in combination with chemical fertilizers at recommended dose of 90: 45: 45 kg NPK ha-1 and at increased seed rate of 133 kg ha -1. At normal seed rate also, organic manuring resulted in higher yields in combination with chemical fertilizers at the higher level of 120: 60: 60 kg NPK ha-1. The available soil N content after harvest was significantly reduced from the content prior to experimentation in all the treatments. The available P status was maintained at the initial level in all the treatments. The efficiency of applied N in terms of grain production/ kg of N applied was greater when organic manures were applied along with inorganic fertilisers. In the absence of organic manure, the apparent recovery of N at normal rates of application was greater than that at higher levels.
Open Access
Agronomic evaluation of biofarming techniques for forage production in coconut gardens
(Department of Agronomy, College of Agriculture, Vellayani, 1996) Sansamma, George; KAU; Raghavan Pillai, G
Two field experiments were conducted at the Instructional Farm, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala State to study the potential of biofarming techniques for forage production in coconut gardens. The study was carried out for a period of two years from September 1993 to August 1995. The influence of the different nutrient management techniques on uptake of nutrients, quality of produce and physico-chemical properties of soil was also investigated. In experiment no.1. the influence of two nitrogen fixing organisms., viz. Azospirillum and Azotobacter and the role of Vesicular Arbuscular Mycorrhiza (VAM) in improving the growth and production of guinea grass and congosignal was studied under inoculation alone and also in combination with chemical fertilizers. The nitrogen fixers were tested under varying levels of fertilizer nitrogen and for VAM the level of phosphorus varied between treatments. The prospects for vermicompost use for guinea grass production was examined under experiment no. 2. It was also envisaged to compare the impact of integrated use of manures and fertilizers with the continuous use of chemical fertilizers alone. Results of experiment no.1 revealed that Azospirillum inoculation alone and in combination with fertilizers had significant positive influence on guinea grass production. Azotobacter inoculation showed only limited effects on growth and yield of the forage grass during the first year but the effect was significant during the second year. The results indicated that 25 per cent of the recommended nitrogen could be saved through the use of either of the biofertilizers. VAM inoculation when combined with full dose of recommended fertilizer nitrogen and potassium, showed significant superiority over the POP treatment at 0, 25 and 50 per cent phosphorus doses while the 75 percent P dose gave comparable yields. The quality parameters of the forage recorded values on par or superior to that of the recommended fertilizer treatment. The use of biofertilizers improved the net income and benefit : cost ratio from guinea grass cultivation. The inoculation treatments were found to have a favourable influence on the physical and chemical properties of the soil. Integrated use of the nitrogen fixing organisms with chemical fertilizers was found effective for Congosignal cultivation. Pooled analysis studies indicated that when inoculated with either Azospirillum or Azotobacter, 50 per cent of the recommended fertilizer nitrogen was adequate for yields. VAM inoculation alone elicited significant yield increase over the absolute control. Combind doses of VAM with chemical fertilizers at all levels of applied phosphorus responded more or less similar to the recommended fertilizer treatment. This indicated the possibility of completely substituting the need for fertilizer phosphorus in VAM inoculated congosignal. The VAM effect in promoting growth and yield of the forage was found to decline in the presence of applied phosphorus. The data on economics also favoured the use of biofertilizers. Experiment no. 2 revealed that guinea grass responded well to integrated use of manures and fertilizers. As per pooled analysis vermicompost @ 5 t ha-1 or Farm yard manure @ 10 t ha-1 when combind with 75 per cent of the recommended NPK were comparable with the 100 per cent NPK treatment. Application of the organic manures improved the quality of the produce. The physic-chemical properties of the soil was also favourably influenced by the integrated use of manures and fertilizers. The economic analysis of the data emphasised the need for reducing the reliance on purchased inputs. Coconut yield was found favourably influenced by intercropping of the fodder grasses.
Open Access
Response of piper longum in coconut gardens to differential spacing and manurial regimes
(Department of Agronomy, College of Horticulture, Vellenikkara, 1996) Sheela, N; KAU; Mercy George
An experiment was conducted during 1994-95 in the KADP farm of the College of Horticulture, Vellanikkara, to evaluate the response of piper longum as an intercrop in coconut gardens to differential spacing and manorial regimes. The experiment was laid out in randomised block design with three replications. The study revealed that plant height, number of branches, number of leaves and total dry matter increased with higher dose of organic manure and 30:30:60 NPK kg ha-1. The optimum spacing was found to be 50 x 50 cm. the above treatment recorded the maximum number of spikes and total dry spike yield (449 kg ha-1). The NPK content of spikes was more than vegetative parts. The nitrogen content decreased as the crop grew but phosphorus content increased and potassium content remained more or less same. The uptake of N,P and K was highest in fertilizer applied plots. The total alkaloid yield was highest in the treatment receiving 50 x50 cm spacing, 20 t ha-1 organic manure and 30:30:60 NPK kg ha-1. The organic and inorganic fertilizers and their combinations did not have any significant effect on the chemical properties of soil. However the plots receiving inorganic fertilizers alone showed a reducing trend in available N, P and K. Thippali cultivation involves high investment for planting material and maintenance and harvesting are also labour intensive. The labour cost in Kerala is very high. It is a crop which requires a periodical harvesting (maximum yield in July –August and October – November months) and care should be taken to harvest only the mature spikes. Thippali being a perennial crop, no net return could be obtained in the first year of planting. The yield level indicated that it should be a profitable crop from the second year of planting.
Open Access
Improving fertiliser use efficiency in sesamum in Onattukara tract
(Department of Agronomy, College of Agriculture, Vellayani, 1996) Regy, V J; KAU; Chandrasekharan, P
An experiment was conducted in the summer rice fallows of the Rice Research station, Kayamkulam during 1995 to study the effect of two levels of nitrogen (22.5, and 30 kg N ha-1) three levels of potassium (0, 22.5 and 30 Kg K2O ha-1) and two methods of application (75 per cent) each of nitrogen and potassium as basal and 25 per cent each of nitrogen and potassium as foliar spray at branching (m1), 50 per cent each of nitrogen and potassium as basal and 50 per cent each of nitrogen and potassium as foliar spray as to equal splits at branching and just before flowering (m2) on the growth, yield, oil and protein content, chemical composition of oil cake, nutrient status of soil after the experiment and economics. The study revealed that nitrogen affected LAI, LAD and NAR, but failed to have any influence on height of the plants, number of branches plant-1, height at which first bearing node formed, RGR, CGR, yield attributing characters, yield and oil content. Test weight, net return, benefit cost ratio, protein content, uptake of nitrogen, phosphorus and potassium at harvest were significantly affected by the applied levels of nitrogen. Nitrogen and phosphorus status of soil after the experiment decreased with higher levels of nitrogen. Higher level of nitrogen resu1 ted in higher nitrogen and phosphorus status of oil cake than lower level of nitrogen. Applied potassium affected most of the growth characters, protein content, oil content, nutrient uptake by the plant at harvest, nutrient status of soil after the experiment, nitrogen and phosphorus content of oil cake, but not the potassium content of oil cake. Oil content increased with increasing levels of potassium from 0 to 30 kg K2O ha-1, but protein content increased only upto 22.5 kg K2O ha-1. Further increase to 30 kg K2O ha-1 decreased the protein content. Methods of application failed to influence most of the growth characters except LAI, LAD,NAR, RGR and CGR. Yield attributes, yield, and quality attributes also had not influence by different methods of application, while nutrient uptake by the plants at harvest, total nitrogen and available potassium status of the soil after the experiment and phosphorous content of oil cake were affected significantly by different methods of application. Interaction between nitrogen and potassium significantly influenced height at first bearing node formed, LAI, LAD, NAR, RGR, CGR, grain yield, net return, benefit cost ratio, oil content, protein content, nutrient uptake by the plants and available potassium status of soil after the experiment, Interaction between nitrogen and methods of application had significantly influenced growth characters, uptake of nutrients and nutrient status of soil after the experiment, Phosphorus content of oil cake was only influenced by different combined application of nitrogen and methods of application.
Open Access
Irrigation management related to sub-surface moisture conservation techniques in oriental pickling melon
(Department of Agronomy, College of Horticulture, Vellenikkara, 1996) Veeraputhiran, R; KAU; Joseph, P A
An experiment was conducted in the summer rice fallows during 1996 at Agricultural Research Station, Mannuthy to study the irrigation management related to sub-surface moisture conservation techniques in oriental pickling melon. The experiment was laid out in randomised block design with three replications. The treatments consisted of combinations of four moisture conservation techniques (control, incorporation of sawdust, paddy waste and coir pith @ 1/3rd pit volume) and four levels of irrigation (IW/CPE ratio of 0.4, 0.8, 1.2 and at critical stages). The study revealed that incorporation of moisture conservation materials increased the growth attributes like length of vine, number of leaves per vine, leaf area, leaf area index and dry matter production and yield attributes like length, girth, weight of fruits and number of fruits per plant. Among the moisture conservation materials paddy waste was found to be the best for incorporation followed by coir pith. The increase in the number of fruits per plant and yield per hectare over control was 30 and 27 per cent respectively by paddy waste incorporation, whereas for coir pith incorporation this increase was 13 and 17 per cent respectively. Oriental pickling melon responded very well to irrigation. Biometric characters (length of vine, number of leaves per vine, leaf area, leaf area index, drymatter production) and yield attributing characters (length, girth, weight of fruits and number of fruits per plant) were favourably influenced by frequent irrigations. The fruit yield increased with increase in frequency of irrigation and was maximum at IW/CPE ratio of 1.2. The interaction effect was found to be significant on growth attributes and yield. It also indicated that the significant effects of moisture conservation materials were pronounced only at closer intervals or irrigation (IW/CPE 0.8 and 1.2) and were more pronounced at the activity growing stages ie. after 45 DAS. Incorporation of moisture conservation materials increased the soil moisture content, consumptive use and water use efficiency. Total consumptive use increased with increase in irrigation frequency. Drier regimes showed a tendency to extract more moisture from deeper layers. The peak consumptive use and crop coefficient were reached maximum between 36-50 and 51-65 DAS respectively. Soil moisture extraction pattern showed that oriental pickling melon on an average depleted 50.7 per cent of the total water use from the top 15 cm layer. Field and crop water use efficiency were higher in less frequently irrigated treatments. N,P and K content of the leaves were enhanced by frequent irrigation and incorporation of paddy waste. Incorporation of paddy waste and coir pith increased the net profit to the tune of 68 per cent respectively over control. Scheduling irrigation at IW/CPE ratio 1.2 was economically better than other irrigation treatments. The combination of moisture conservation techniques and levels of irrigation further increased the net profit and net return per rupee invested over the individual effects. Best net profit was obtained when the crop was irrigated at the IW/CPE ratio of 1.2 with the incorporation of paddy waste. If water is scarce for irrigation, incorporation of paddy waste or coir pith and irrigation at IW/CPE ratio 0.8 was highly beneficial than crops at the closer interval of IW/CPE ratio 1.2 without any moisture conservation material.

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