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Open Access
Combined application of granular preparations of pre-emergent herbicides and fertilizers in rice
(Department of Agronomy, College of Horticulture, Vellanikkara, 1995) Bindu, N K; KAU; John, P S
A field experiment was conducted at the Agricultural Research Station, Mannuthy under the Kerala Agricultural University during the first crop season of 1994 to find out the effect of pre-emergent herbicides and fertilizers in rice. The experiment was laid out in a randomized block design and consisted of fourteen treatments with three replications. Broadleaved weeds and sedges dominated the field. Among broadleaved weeds, Mono choria vaginalis and sphenocleazeylanica were predomint. Shoenoplectus lateriflorus and Cyperus difformis were the prominent sedges present in the field and Echinochloa colonum,saccolepis interrrupta and Isachne miliacea were the important grasses present. Butachlor, anilofos and oxyflourfen under different methods of application reduced the weed Population. Though oxyflourfen recorded high weed control efficiency, it was highly phytotoxic to the rice crop and resulted in poor crop stand. Butachlor and anilofos applied as homemade granular (GP) preparation or as spray alone, or in combination with fertilizer was safe to the crop. The available nutrient in the soil was not affected by the different methods of application of butachlor and anilofos, alone or when combined with fertilizer. Butachlor and anilofos as spray or as GP applied alone, or in combination with fertilizer recorded similar crop growth characteristics, yield and yield attributes. Nutrient up taken by weeds was lower in butachlor and anilofos treatment. Lower weed index values were recorded in butachlor and anilofos treatment. The highest return per rupee was obtained from anilofos treatments. The highest return per rupees was obtained from anilofos treatments. In general, combined application of anilofos or butachlor GP with fertilizer gave efficient control of weed, produced higher grain yields and high return per rupee invested. It also reduced cost, energy and time of weed control operation.
Open Access
Investigation on allelopathic influence and control of purple nuts edge
(Department of Agronomy, College of Agriculture, Vellayani, 1999) Ameena, M; KAU; Sansamma, George
Lab and field experiments were conducted at the Instructional farm, College of Agriculture, Vellayani to study the allelopathic influence of Purple nutsedge (Cyperus rotund us L) on important field crops; to investigate the effectiveness of systemic herbicides for control of nutsedge and also to assess the effect of chemical weed control on growth and yield of subsequent field crops. In Ex. no. I, allelopathic influence of purple nutsedge on important field crops like rice, ragi, cowpea, green gram, bitter gourd and bhindi were studied. The treatments comprised of aqueous extracts and blended extracts of fresh and dry plant parts of nutsedge. The results revealed that aqueous extracts of nutsedge inhibited germination of rice, ragi, bitter gourd and bhindi while it had some stimulatory effect on germination of cowpea and green gram. The early growth characters of the field crops were found suppressed by the aqueous extract treatment while the blended extract showed no effect. In general, the dry plant parts showed greater effect than the fresh material. Under Ex.no.Il, field studies were made to investigate the effectiveness of systemic herbicides viz. Glyphosate and 2,4-D for control of nutsedge. The treatments included different doses of the herbicides with and without adjuvants and Glyphosate combined with sublethal dose of 2,4-D. The results revealed that lowest dose of the herbicides were sufficient for complete kill of the purple nutsedge plants in the experimental area and there was no regrowth upto 6 weeks. There was significant reduction in viability of tubers collected one month after herbicide application, but the tubers tested 45 days after spraying showed an increase in germinability over the record on 30th day. Tubers from treatments involving Glyphosate with sublethal dose of 2,4-D recorded the lowest sprouting percentage indicating the possibility for weed control for a longer period. In Ex. no. In, the persistence of the herbicides in soil were monitored and it was observed that early growth of cucumber sown on the same day of herbicide application was affected while that sown on soils collected 10 days after spraying recorded growth characters comparable to that of control. From Ex.no.IV, it could be inferred that chemical weed control did not show any deleterious effect on growth and yield characteristics of ragi and cucumber sown 15 days after the treatments. Application of 2,4-D for nutsedge control was found superior to other treatments in terms of net income and B:C ratio and the lower unit cost of the chemical was precisely the reason for its superiority.
Open Access
Development of subsurface pad irrigation system for tomato
(Department of Agronomy, College of Agriculture, Vellayani, 1995) Abdul Nassar, K; KAU; Jaikumaran, U
An experiment was conducted in the summer rice fallows of the Agricultural Research Station, Mannuthy during 1995 to develop and test subsurface pad irrigation system for tomato and to compare it with surface irrigation. The soil was sandy clay loam, medium in organic carbon and available potassium and high in available phosphorus. The eight treatments comprised of combination of four frequencies of irrigation (IW/CPE ratios of 1.2, 0.9, 0.6 and 0.3) and two irrigation systems (subsurface pad irrigation and surface irrigation). The experiment was laid out in randomized block design with three replications. Poly bags filled with saw dust placed 45 cm beneath the surface at the frequency of one pad for every four plants formed SSPI. Water was supplied to pads by laterals supplying 40 mm of water per irrigation. The study revealed that tomato responded very well to irrigation. Biometric characters like plant height, number of leaves and leaf area index and yield attributing characters like number of flowers, number of fruits and total weight of fruits per plant were favourably influenced by frequent irrigation under both the systems of irrigation. The fruit yield increased with frequency of irrigation and maximum at the IW/CPE ratio of 1.2. The plants irrigated by surface method grew taller, had more leaf area index, produced more number of green leaves, flowers, fruits and total fruit weight per plant compared to the plants irrigated under SSPI system at the irrigation frequencies of IW/CPE ratios 1.2, 0.9, and 0.6. But at the IW/CPE ratio of 0.3, the subsurface irrigated plants performed better than the surface irrigated plants both in terms of growth and yield attributing characters. The crop receiving irrigations through SSPI systems consumed lesser amount of water at all the frequencies of irrigation compared to surface method. This decline at the IW/CPE ratios of 1.2, 0.9, 0.6 and 0.3 were to the tune of 22,30,40 and 18 per cent respectively. The soil moisture extraction from 0-15, 15-30 and 30-60 cm layers in SSPI was 62-70, 24-29 and 6-12 per cent respectively whereas in surface irrigation the respective values were 62-64, 22-23 and 13-15 per cent. The soil moisture redistribution was rapid in the case of surface irrigation whereas it was gradual in the case of SSPI. Moisture content in the case of SSPI was maximum at the radial distance of 15 cm from the pad on either sides whereas in surface irrigation there was no remarkable difference in the moisture content with respect to radial distance from the plant.
Open Access
Bio farming in vegetables : effect of bio fertilizers in amaranth
(Department of Agronomy, College of Agriculture, Vellayani, 1998) Niranjana, N S; KAU; Meerabai, M
An experiment was conducted at the Instruction farm attached to the College of Agriculture, Vellayani, during April - Sept 1996 with objectives of finding out the impact of biofertilizers Arospirillum , AMF and dual inoculation under varying and varied levels of fertilizer on amaranthus. Study also aimed to note the economics of the integrated approach and to identify the best economic combinations which improve yield and quality of amaranth varieties Arun and Kannara local. The study had three controls and two number of replications. The results of the study revealed that yield attributing characters like no: of harvests, yield harvest", marketable yield and dry weight were highest in plots applied with dual inoculation of Azospirillum and AMF with 75 per cent dose of p.op. Azospirillum with 50 per cent POP also gave good results. Both these treatments were on par and was better than our state recommendation. Growth characters viz: Seedling growth rate, plant height, number of leaves per plant, number of branches per plant, LAI were highest. for Azospirillum inoculation at early stages. While AMF inoculation gave notable results at later stages. Physiological parameters namely Biomass, NAR, Root dry weight were significantly improved with dual inoculation and higher dose of chemical fertilizer. Leaf dry weight, RGR and CGR responded most to inoculation with Azospirillum at early stages, while at later stage AMF performed well. Kannara local was superior to 148 Arun at early stages. But Arun performed superior to Kannara local with the progress of time. Stem dry weight was significantly influenced by application of AMF. Vermicompost gave high biomass till 45 DAT. Quality of amaranth improved when biofertilizer was given with higher dose of chemical fertilizer in almost all parameters discussed. Dual inoculation with 75 per cent POP gave maximum content of total mineral and moisture. Ascorbic acid content was highest for the treatment dual inoculation with 25 per cent POP. AMF with 75 per cent POP recorded high protein content, the same bioagent with 50 per cent POP gave lowest content of oxalates. Less fiber flush of amaranth w.as got from plots given Azospirillum + 75 per cent POP. Uptake of major nutrients namely Nand P was influenced by inoculation of Azospirillum along with higher dose of chemical and AMF with lower inorganics respectively. Major nutrient status in the soil after the experiment was more in case N,P,K for dual inoculation, Arospirillum and AMF respectively. Irrespective of biofertilizer higher dose of inorganic gave greater residual amount of nutrients. Dual inoculation with 75 per cent dose and Azospirillum along with 50 per cent dose gave maximum l?:C ratio and net returns. Vermicompost recorded minimum disease score. Lower levels of chemical fertilizers recorded less infection.
Open Access
Effectiveness and crop seletivity of pre-emergence herbicides under different methods of application in puddled rice
(Department of Agronomy, College of Horticulture, Vellanikkara, 1995) Mohan Kumar, P D; KAU; Savithri, K E
A field experiment was conducted at the Agricultural Research Station, Mannuthy under the Kerala Agricultural University during the second crop season of 1992-93 to find out the effectiveness and crop selectivity of pre-emergence herbicides under different methods of application in puddled rice. Twelve treatments were com- pared with two controls (hand weeded and unweeded). The experiment was laid out in Randomised Block Design with three replications. Sedges and broadleaved weeds dominated the weed flora. Among the sedges, Schoenoplectus lateriflorus, Cyperus iria, C. difformis and Fimbristylis miliacea were the prominent species, and the broadleaved weeds included Mono- choria vaginalis, Marsilia quadrifoliata, Sphenochlea zeylanica and Nymphaea nouchali. The broad leaved weeds were effectively controlled by pretilachlor + safener, oxyflourfen and pendimethalin, besides butachlor and thiobencarb. All the herbicides except pendimethalin and anilofos gave good control of sedges. Oxyflour- fen spray showed the highest weed control efficiency among the herbicides tested. Sand mixed broadcasting of herbicides was found to be lesser toxic than spray in all the herbicides except pretilachlor + safener, where the safener present protected the crop completely from phytotoxicity. Crop growth characteristics were highly influenced by the herbicide and method of application. Pretilachlor + safener, oxyflourfen and thiobencarb were found superior. Yield attributes were relatively unaffected by the different treatments. Pretilachlor + safener spray recorded the highest yield, among herbicides. Sand mixed broadcasting of all other herbicides produced a slightly higher grain yield compared to spray. Nutrient uptake by crop was directly related to the dry matter accumula- tion. The lowest weed index value was registered by pretilachlor + safener spray. Pretilachlor + safener spray recorded the highest total returns and its sand mixed broadcast realised the highest return per rupee invested on weed control.
Open Access
Dynamics of the absorption of forms of N by crops plants
(Department of Agronomy, College of Horticulture, Vellanikkara, 1995) Retheesh, P K; KAU; Balachandran, P V
An investigation was conducted at the Radiotracer Laboratory, College of Horticulture, Vellanikkara in the year, 1993 which consisted of two parts. In the first part absorption of different forms of nitrogen relative to its concentrations at different growth stages of rice was studied using labelled and non-labelled fertilizers. To know the molecular absorption of urea 14C-labelled urea fertilizer was used and the presence of 14C in the plant was taken as an evidence for the absorption of molecular form of urea. In the case of ammoniacal and nitrate forms of N, 15N-labelled and non-labelled materials were used alternately to find out the preferential absorption. In the second part of the investigation an attempt was made to know the possibility of molecular absorption of urea by a few selected plantation crops. The uptake of N and dry matter production were higher when rice plants were supplied with a combination of ammonium and nitrate in equal proportions. Among the three forms of nitrogen supplied at different combinations, nitrate N recorded the highest uptake when present along with urea N or ammoniacal N or both. Though the presence of urea had a repressing effect on the uptake of nitrate, ammonium enhanced the nitrate uptake. The uptake of nitrate N was more in the presence of ammonium than in its absence. With respect to ammonium uptake it was found that urea and nitrate had more or less similar influence on it. It was seen that rice plants absorbed molecular form of urea even in the presence of other readily available forms of nitrogen. The molecular absorption of urea by rice plants was found to vary from 12-18 percentage of the total N uptake. When urea was supplied along with ammonium and or nitrate the uptake of urea was found reduced. The quantity of urea absorbed by the plantation crops was found negligible and ranged from 0.5-3.3 µg per g of the plant dry weight.
Open Access
Nutrient Status of the soil and plant as influenced by spacing and continued manuring in Coconut
(Department of Agronomy, College of Agriculture, Vellayani, 1998) Pratheep, M S; KAU; Purushothaman Nair, N
A study was conducted during 1995-96 at Coconut Research Station, Balaramapuram of Kerala Agricultural University to asses the nutrient status of . the soil and plant in West Coast Tall coconuts planted at three different spacings and manured with three levels of macro nutrients. The treatments were three spacings (5 m x 5 m, 7.5 m x 7.5 m and 10 m x 10 m) and three fertilizer levels (control i.e., zero NPK, the lower level i.e., 340 g N + 225 g P205 + 450 g K20 per palm per year and the higher level i.e., 680 g N + 450 g P205 + 900 g K20 per palm per year). The basic experiment was started in 1964 and being continued. The data collected during the study (1995-96) was statistically analysed and the results are presented here under. Closer spacing increased height of palms. The spacings of7.5 m x 7.5 m was statistically superior since it gave the highest nut yield per palm per year. Manuring increased height of palms, girth and leaf production. At the highest level of NPK closer spacing of 5 m x 5 m could give the highest yield per unit area. Female flower production was higher under 7.5 m x 7.5 m spacing. Fertilizer application also increased flower production. Fruit setting was not influenced by palm density and fertilizer application significantly increased fruit setting. Number of nuts per bunch was higher at the spacing of 7.5 m x 7.5 m and progressively increased with manuring. The weight and volume of unhusked nut was the lowest at the closest spacing and in unfertilized palms. There was increase in weight of husk with increase in spacing. Similarly there was an increase in the ratio of weight of husk to unhusked nut with increasing spacing. Maximum thickness and weight of kernal was recorded at the spacing of 7.5 m x 7.5 m. Copra out turn was more at the spacing of 7.5 m x 7.5 m. In manured palms there was a higher copra out turn per hectare contributed by the higher yield. The oil content of copra was negatively correlated with per palm yield. Available NPK of soil decrease with wider spacing. The soil nutrient status increased with application of macronutrients and the accumulation of fertilizer was more in the upper layer of 0 to 25 cm. There was decline in NPK status with increase in depth. The Ca and Mg content of soil decreased with increase in spacing up to 7.5 m x 7.5 m. Both Ca and Mg content of soil decreased with increase in macro nutrient application. Ca content of soil decreased with increase in depth. However, the decrease of Mg content was seen only up to 50 cm depth. Available micro nutrients (Fe, Cu, Mn and Zn) decreased with increase in spacing and application of fertilizers. Available Fe, Cu and Mn content of soil decreased with increase in depth. Nand P content of leaf of coconut increased with wider spacing. However K content decreased with spacing. All the three macro nutrients increased with increase in fertilizer application. Ca and Mg content of leaf also increased with increase in spacing and fertilizer application. By fertilizer application Fe, Mn and Cu content of leaf increased whereas Zn and Na decreased.
Open Access
Agronomic evaluation of chemical and bio-agents on phosphorus dynamics in red loam soils of southern Kerala
(Department of Agronomy, College of Agriculture, Vellayani, 1995) Viswambharan, K; KAU; Sasidhar, V K
Three field experiments were conducted at the Instructional Farm, College of Agriculture, Vellayani during 1992-'93 for two season to study the effect of chemical and bio-agents on phosphorus dynamics in the red loam soils of Southern Kerala. In the experiment No.1 four treatments such as no anions, hydroxide, carbonate and silicate were tested under three levels of phosphorus such as no phosphorus, 50% phosphorus and 100% phosphorus. From the study, it was revealed that carbonates have more desorbing power for phosphorus than the other anions tested. These were reflected in the yield and yield attributes, available phosphorus content of the soil, soil phosphorus fractions, nitrogen and phosphorus uptake of plants. Among the combinations, carbonate anion with 50% phosphorus gave the highest yield. In the experiment No.2, three treatments such as no chelates, EDTA and DTPA were tested with three levels of phosphorus such as no phosphorus, 50 % phosphorus and 100% phosphorus. From the study it has been revealed that EDTA gave better response than other chelates tested. These were reflected in the yield, yield attributes, available phosphorus content of the soil, soil phosphorus fraction, nitrogen and phosphorus uptake of plants. Among the combinations EDTA with 50% phosphorus gave the highest yield. In the experiment No.3, four levels of microbial agents such as no microbes, VAM, PB and VAM + PB were tested with three levels of phosphorus such as no phosphorus. 50% phosphorus and 100% phosphorus. From the study it has been revealed that VAM + PB gave the highest response. This was reflected in the yield attributes, available phosphorus content of the soil, soil phosphorus fractions, nitrogen and phosphorus uptake of plants. Among the combinations VAM+PB with 50% phosphorus gave the highest yield.
Open Access
Biomass production of green manure crops and mineralization of organic nitrogen in coconut basins
(Department of Agronomy, College of Horticulture, Vellanikkara, 1995) Tanie Thomas; KAU; John, P S
An investigation on biomass accumulation of green manure crops and mineralization of organic nitrogen in coconut basins was conducted at the College of Horticulture, Vellanikkara during 1993-94. The experiment was aimed at evaluating the performance of various green manures and cover crops grown in coconut basins based on their biomass accumulation, nutrient accretion and nitrogen dynamics in the soil after incorporation. The mineralization pattern of green manure in red and laterite soils was studied in a laboratory incubation study using 15N labelled green manure. The salient results of the investigation are abstracted below. Crotolaria striata which represented the neglected green manures and pueraria phaseoloides which represented the cover crops produces the maximum dry matter in coconut basins. The popular green manure Crotolaria junecea failed to grew and put forth good biomass accumulation under coconut. The highest N content was found to be with Pueraria. Cassia tora was found to be the richest source of P. The maximum K content was reported in Cassia tora and Sesbania aculeata. Pueraria phaseoloides and Crotolaria striata released the maximum quality of nitrogen to the soil. The ammonium-N accumulation was found to be high in the upper layer of 0 to 15 cm soil when compared to the 0 to 30 cm soil layer. Crotolaria striata and Pueraria released the highest amounts of ammonium-N. In the release of nitrate-N, Pueraria was found to be the most efficient closely followed by Crotolaria striata. In the case of total mineral N (ammonium+nitrate) content the highest quantity was extracted with Crotolaria striata followed by Pueraria. In the incubation experiment to study the pattern of mineralization green manure N, the N release in terms of 15NH4 extracted during different periods of incubation was the highest for Crotolaria striata followed by Sesbania aculeata. The mineralization of green manure 15N took place at a lower rate in laterite soil when compared to red soil.

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