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Open Access
Time of application of pre-emergence herbicides in dry-sown rice
(Department of Agronomy, College of Horticulture, Vellanikkara, 1989) Suja, G; KAU; Abraham, C T
Open Access
Spatial arrangement and nutrient management for maize- fodder cowpea intercropping in rice fallows
(Department of Agronomy, College of Agriculture Vellayani, Trivandrum, 1989) Geetha Kumari, S; KAU; Mohamed Kunju, U
An investigation was carried out during the summer season of l987-88 in the instructional farm attached to the College of Agriculture Vellayani to determine the best crop arrangement for a grain maize fodder cowpea inter cropping in summer rice fallows under different fertility levels • The different crop arrangements. tried were pure crop of maize at normal row arrangement, maize at normal row arrangement, + one, row of cowpea in between the maize pure crop of maize at paired row arrangement two rows of cowpea in the interpair spaces maize at paired rows of cowpea.
Open Access
Phosphorus management in a rice based cropping system
(Department of Agronomy, College of Agriculture, Vellayani, 1989) Annamma, George; KAU; Sasidhar, V K
In order to standardize an appropriate phosphorus management practice in a rice based cropping system involving rice-rice-cowpea/sesamum, field experiments were carried out in the rice fields of the Instructional Farm, College of Agriculture, Vellayani from June 1984 to September 1986. The experiment was laid out in a randomized block design with three replications. There were eight treatments. The treatments comprised of (1) continuous phosphorus application to all the three crops in the system (2) phosphorus application to the first and second crops of rice (3) phosphorus application to the first crop of rice and third crop of cowpea/sesamum (4) phosphorus application to the first crop of rice only (5) phosphorus application to the second crop of rice and third crop of cowpea/sesamum (6) phosphorus application to the second crop of rice only (7) phosphorus application to the third crop of cowpea/sesamum only (8) control plot with no addition of phosphorus to any of the crops in the system. The salient findings of the experiment are as follows: Phosphorus application had no significant influence on grain and straw yield of first crop of rice. But available nitrogen, available and total phosphorus and available potassium of the soil were increased with phosphorus application. Direct, residual and cumulative effects of phosphorus had no significant influence on grain and straw yield of second crop of rice. Phosphorus uptake could not show any variation due to the different treatments. Available and total phosphorus content of the soil were highest under cumulative phosphorus treatment. All the growth and yield attributes of third crop of cowpea and sesamum were increased by the direct and cumulative effects of phosphorus. Grain yield of cowpea was significantly increased by the direct application of phosphorus. Eventhough not significant the highest sesamum yield was accorded by the direct and cumulative application of phosphorus. Phosphorus uptake in all the growth stages of the crop was highest in direct phosphorus plots. Available and total phosphorus content of the soil was highest in continuous phosphorus applied plots. There was no significant influence on grain and straw yield of first crop of rice after cowpea and sesamum in the direct, residual and cumulative effects of phosphorus. Residual phosphorus was sufficient to maintain the available nitrogen status of the soil. Available phosphorus of the soil was increased by the direct, cumulative and continuous application of phosphorus and total phosphorus by continuous application of phosphorus. Balance sheet of available phosphorus revealed that the soil phosphorus level almost maintained, where phosphorus was applied only to the third crop of cowpea or sesamum. The highest net return and benefit-cost ratio for the rice-rice-cowpea and rice-rice-sesamum system was obtained when phosphorus was applied only to the third crop in the rice fallow and the residual effect being utilized by the succeeding rice crops.
Open Access
Nutrient management in bitter gourd under partial shade
(Department of Agronomy, College of Agriculture, Vellayani, 1989) Ravikrishnan, M K; KAU; Sasidhar, V K
A field experiment was conducted at the College of Agriculture, Vellayani during 1988 to study the influence of three levels of each nitrogen (50, 70 and 90 kg/ha), phosphorus (15, 25 and 35 kg/ha) and potassium (25, 50 and 75 kg /ha) on growth, yield, content and uptake of major nutrients in bittergourd VK-1 (Priya) under partially shaded conditions of coconut gardens. The trial was conducted as 33 + 1 partially confounded factorial experiment in Randomised Block design with two replications. Higher levels of nitrogen had profound influence on growth characters like days for opening of first male and female flowers and their node of emergence, internodal length, length of main vine and total dry matter production. Application of phosphorus of 35 kg/ha had significant positive effect on the node of emergence of first female flower and total dry matter production. Yield attributes like sex ratio, fruits per plant and harvest index were not influenced significantly by the main and interaction effects of the major nutrients. However the control plots registered a significant reduction in values for these parameters. The fruit set was maximum at 90 kg/ha of nitrogen, 25 kg/ha of phosphorus and 25 kg/ha of potash. Application of 90 kg N/ha, 25 kg P2O5/ha and 50 kg K2O/ha recorded the maximum yield. The response of bittergourd to nitrogen levels was linear and that to phosphorus levels was quadratic. Application of potassium at 75 kg K2O/ha was found to significantly increase the fruit weight. The length and girth of the fruits were positively influenced by the application of nitrogenous fertilizer. Potassium at the rate of 75 kg K2O/ha recorded the maximum girth of fruits signifying its effect on this character. The nitrogen and phosphorus content of fruits and plants and protein content of fruits were found to be unaffected by the main effects of nitrogen, phosphorus and potash. An increase in potash level increased the potassium content of fruits and plants. Nitrogen at 90 kg/ha significantly increased the nitrogen uptake by plants and fruits and phosphorus uptake by plants as compared to other levels. Maximum potassium uptake by fruits was obtained by application of 35 kg P2O5/ha and 75 kg K2O/ha and uptake of potassium by plants was maximum at 90 kg N/ha, 35 kg P2O5/ha and 75 kg K2O/ha. The study indicated that application of 90 kg N/ha 25 kg P2O5/ha and 50 kg K2O/ha recorded the maximum yield and net returns from bittergourd cv. VK-1 (Priya) under partially shaded conditions of coconut gardens in the red loam soils of Vellayani.
Open Access
Seed production in stylosanthes gracilis under varying levels of population density, nutrition, moisturiser regimes and cuttings
(Department of Agronomy, College of Agriculture, Vellayani, 1989) Balachandran Nair, G K; KAU; Sreedharan, C
An investigation was carried out during the period from July 1980 to March 1982 in the Instructional Farm, College of Agriculture, Vellayani to study the agronomic techniques required for maximum seed production in Brazilian lucerne (Stylosanthes gracilis). The following three separate field experiments were conducted and data collected and analysed. The first experiment entitled ‘influence of cultivars and plant population on seed production’ was laid out as a22 Factorial Experiment in R. B. D and replicated five times with the objective to find out the best cultivar of Stylosanthes gracilis for seed production along with the seed rate. The treatments consisted of combinations of two cultivars of Stylosanthes gracilis viz. Schofield and Cook, and two seed rates viz. 2.5 and 5 kg/ha. The second experiment entitled ‘nutritional requirements of Stylosanthes for seed production’ was laid out as a32 Factorial Experiment in R. B. D and replicated thrice with the treatment combinations of three levels of phosphorus viz.80, 120 and 160 kg P2 O5/ha and three levels of lime viz. no lime, 375 and 750 kg lime/ha. The objective was to assess the phosphorus and lime requirement of the crop for maximum seed yield. The third experiment entitled ‘Effect of moisture regimes and cuttings on seed production’ was conducted as a 32 Factorial Experiment in R.B. D and replicated thrice with treatment combinations of three irrigation schedules (IW/CPE ratios) viz. 0.50, 0.75 and 1.00 and three cutting schedules viz. no cutting, one cutting and two cutting. The objective was to investigate the efficiency of irrigation schedules and cuttings on seed yield. The results from the investigation revealed that the variety cook produced significantly higher seed yield of about 64 kg/ha as against 35 kg/ha obtained from the variety schofield. The seed rate of 5 kg/ha gave the higher seed yield of about 56 kg/ha as against the seed yield of about 43 kg/ha under the seed rate of 2.5 kg/ha. The seed yield attributing characters like setting percentage of seeds and number of seeds per plant were maximum for the variety cook. All the growth characters contributed to about 66 per cent of the variation in seed yield. The highest net return per hectare was obtained when the variety schofield was grown under a seed rate of 2.5 kg/ha. Application of phosphorus at 120 kg and lime at 375 kg per hectare gave maximum seed yield of about 80 kg/ha. It was also found that higher levels of phosphorus like 120 or 160 kg/ha helped to increase the setting percentage of seeds. The biometric characters such as spread of plants, number of branches and LAI were significantly influenced by the application of 120 kg phosphorus and 375 kg lime per hectare. The nutrients uptake was also enhanced by the application of phosphorus and lime at the above levels. The growth characters influenced the seed yield by 53 per cent. The economic optimum doses of phosphorus and lime for maximum seed yield were found to be 149 kg and 593 kg per hectare respectively. The highest gross and net returns were obtained from plots treated with phosphorus and lime at 120 kg and 375 kg per hectare respectively. Irrigating the crop at IW/CPE ratio 1.00 gave the maximum seed yield of 89 kg/ha. When the crop was left without cut it produced the highest seed yield of 92 kg/ha. The maximum setting percentage of seeds and leaf production were observed when the crop was irrigated at ratio 1.00 and without cut. The no cutting treatment gave maximum number of seeds per plant. The biometric charaters like height, spread, number of branches and length of branches were all found maximum in treatments where no cutting was given. Maximum water use efficiency for seed production was recorded by the lowest irrigation ratio of 0.50 and also when the crop was left without cut. About 46 per cent of the variation in seed yield was explained by the growth characters. Maximum net return per hectare was obtained when the crop was irrigated at IW/CPE ratio 1.00 and without cut.
Open Access
Biomass productivity and nutrient accumulation in sesbania rostrata inoculated with rhizobium
(Department of Agronomy, College of Agriculture, Vellayani, 1989) Murali, S; KAU; Muraleedharan Nair, V
With a view to study the biomass productivity and nutrient accumulation of Sesbania rostrata, a field experiment was initiated at college of Agriculture, Vellayani during summer of 1988-’89. The investigation was carried out as two separate experiments. The objective of Experiment I was to assess the biomass productivity and nutrient accumulation of Sesbania rostrata in relation to other green manures, viz. Sesbania aculeata and Crotolaria juncea. The second experiment was intended to determine the effect of Rhizobium inoculation, Liming and phosphorus application on the biomass productivity of Sesbania rostrata. The experiment (s) were laid out in randomized block design with three replications. The soil of the experimental site(s) was sandy clay loam, low in available nitrogen and phosphorus and medium in available potassium. An abstract of the results is given below. Optimum time of harvest of the green manures during the third crop season in rice fallows was at flowering stage(50 DAS), since all the parameters investigated showed a maximum value at this period. Among the green manures tried, Crotolaria juncea proved to be superior in terms of green matter yield, dry matter yield and nutrient up take followed by Sesbania aculeata. At final harvest (50DAS) Crotolaria juncea plant, yielded 14.98 t/ha of biomass, 5.36t/ha of dry matter and yielded 103.78kg/ha, nitrogen. The performance of Sesbania rostrata was not at all satisfactory under the agro-climatic conditions of Trivandrum during the summer season. The present study indicated the superiority of Crotolaria juncea as a green manure under Trivandrum conditions during the summer, as compared with the other two green manures tried. Highest level of lime application (500kg/ha) tried in the experiment together with inoculation positively influenced the growth parameters, nutrient uptaken , soil content of nitrogen, phosphorus, calcium and Rhizobium population . Net returns and cost-benefit ratio also showed higher values for the said treatments. Though phosphorus application at 30kg/ha positively influenced the said parameters, its effect was negligible and greatly nullified by the cost of fertilizer which resulted in a lower net profit and cost-benefit ration. Thus, it is revealed from the present study that phosphorus application is not absolutely necessary for growth of Sesbania rostrata under the agro-climatic conditions of Trivandrum district.
Open Access
Influence of levels of nitrogen, methods of application and plant population on the performance of the high yielding rice variety sabari
(Department of Agronomy, College of Agriculture, Vellayani, 1989) Mohamed Kunju, U; KAU; Sadanandan, N
An investigation was undertaken to study the effect of different levels and methods of nitrogen application and different plant populations on the growth, yield and quality of the rice variety sabari in the southern Region of Kerala. The treatments consisted of four levels of nitrogen (40,80,120 and 160 kg/ha), two methods of application of nitrogen (application of the entire dose through soil and 75 per cent through soild plus 25 per cent through foliage) and three levels of spacing viz.10x10cm (100 hills/m2) 10x15 cm (67 hills /m2) and 10x 20 cm (50 hills m2). The experiment was laid out in split-plot design, replicated thrice and conducted for two years at the Instructional Farm, College of Agriculture, Vellayani. Growth characters like plant height, number of tillers per hill, leaf area index and dry matter production at different stages of growth increased with incremental doses of nitrogen. Closer planting resulted in smaller plants and higher number of tillers per unit area. The leaf area index was high in closer planting. Total dry matter production at harvest was more in 10x15 cm spacing. Foliar application of nitrogen (25 per cent) increased the total dry matter production at harvest. Increasing levels of nitrogen delayed flowering. Number of panicles per unit area, length of panicle, weight of panicle, number of spikelets per unit area filled grains per panicle and number of grains per unit area were increased due to incremental levels of nitrogen. Application of the second top dose of nitrogen through foliage produced more number of panicles. It also increased the weight of panicle, number of filled grains per panicle and number of filled grins per unit area. Test weight of grain was more at higher levels of nitrogen. Foliar application also increased the test weight of grain. Maximum yield of grain was recorded at 120 kg/N/ha which was on par with 160 kg N/ha. The average yields of grain at the 40,80,120 and 160 kg N levels were 3149, 3818, 4106 and 4027 kg/ha respectively. Foliar application of the second top dose of nitrogen was superior to soil application in increasing grain yield. Higher grain yield was obtained at 10x15 cm spacing. Quadratic response curve was found to be a suitable fit for nitrogen dose. The overall economic optimum level of nitrogen was 120 kg/ha. It was low (109 kg/ha) at closer spacing and high (124 kg N/ha) at wider spacing. Straw yield was increased with increasing levels of nitrogen application. Foliar application also increased the straw yield. Foliar application of nitrogen resulted in higher grain straw ratio while higher levels of nitrogen decreased the ratio. Increasing doses and foliar method of nitrogen application increased the nitrogen content of plants at flowering and of straw and grain at harvest. Protein content of grain was high at higher levels of nitrogen. It was also increased due to foliar application. The uptakes of nitrogen, phosphorus and potassium were more at higher levels of nitrogen and foliar application. This was not influenced by different spacings. Increasing levels of nitrogen application resulted in only a marginal increase in the residual available nitrogen status of the soil. Residual available phosphorus and potassium in the soil were not appreciably influenced by any of the treatments. Net income and benefit cost ratio were highest at 120 kg N/ha. Foliar application also increased the net income. Among the different spacings 10x15 cm spacing recorded the maximum net income. A combination of 120 kg N/ha of which 25 per cent applied through foliage at the panicle initiation stage with 10x15 cm spacing was found to be the most ideal for maximum benefit from the rice variety sabari under the agroecological situations of the southern Region of Kerala.
Open Access
Carry over effects of summ crops on virippu rice
(Department of Agronomy, College of Agriculture, Vellayani, 1989) Regina Lily, Edwin; KAU; Koshy, E P
With a view to evaluate the carry over effects of different summer crops on virippu rice and to test the effects of three different levels of NPK, fertilizers on the growth and yield of rice, two filed experiments were conducted at the Instructional farm, college of Agriculture, Vellayani during 1987. The experiment was laid out in randomised block design with three replications. There were five summer treatments (grain type cowpea, daincha, sesamum, maize and fallow) preceding rice and three NPK levels tried on rice. The fertility levels were (i) F0 – No fertilizers. (ii) F1 – Half the recommended dose. (iii) F2 – Full recommended dose. The rice variety used was Jaya. The abstract of the results are given below. Daincha and cowpea resulted in the maximum number of tiller production. Proportionate increase in the number of tillers with the quantity of fertilizers was observed. Highest LAI of rice was observed after daincha. Daincha incorporation during summer recorded the maximum uptake of all the three nutrients by rice in the virippu season. Among the systems cowpea-rice depleted the soil of maximum quantity of nitrogen and potassium. P uptake was highest in the daincha-rice system. Application of full recommended dose caused maximum uptake of the major nutrients. The number of spikelets per panicle, number of filled grains per panicle, weight of the panicle and the test weight of rice crop were higher in the daincha- rice sequence. In general these yield attributes showed linear response to the quantity of NPK fertilizers in all the systems tried. The grain yield, straw yield, biomass production and harvest index of rice were maximum when it was preceded by a summer crop of daincha. With daincha incorporation insitu, half the recommended dose of NPK fertilizers (f1) was sufficient to get yields same as that of full compliment of NPK fertilizers (f2). In the other systems the results obtained were in proportionate to the quantity of fertilizers. The organic carbon, total nitrogen and available P2O5 content of the soil were highest after daincha and available potassium after cowpea. Among the sequences, daincha-rice system best maintained the total N and available P2O5 content available K2O of the soil. The three different fertility levels could exert no significant influence on the total nitrogen and the available P205 content of soil. A positive N balance was observed in the cowpea-rice and the daincha-rice sequences. In sesamum-rice, maize-rice and fallow-rice the balance was negative. The P balance of soil was maintained positive in all the sequences except fallow-rice. All the cropping sequences tried resulted in the positive balance of K. The three fertility levels could not exert any significant influence on the N and P balance of soil after the five sequences tried. The k balance of the soil was proportionate to the quantity of fertilizers in the daincha-rice, sesamum-rice and fallow-rice sequences. The sesamum-rice sequence was found to be the most profitable among the five sequences tried. Highest cost-benefit ratio was registered in the cowpea-rice system.
Open Access
Response of rice to applied sulphur
(Department of Agronomy, College of Horticulture, Vellanikkara, 1989) Sherine George; KAU; Ashokan, P K
Experiments were conducted at the Agricultural Research Station, Mannuthy and the Radiotracer Laboratory of the Kerala Agricultural University during the first crop season of 1988 to study the response of rice to applied sulphur and the relative uptake and distribution of soil and fertilizer sulphur. There was a field experiment conducted with four levels of sulphur (0, 20, 40 and 60 kg ha-1) and four sources of sulphur (ammonium sulphate basal dressing, ammonium sulphate-top dressing, ammonium phosphate sulphate and elemental sulphur). The experiment was laid out in RBD in plots of size 4.6 m x 4.5 m and replicated thrice. A pot culture experiment was conducted for studying the uptake and distribution of 35 applied as albelled (MH4) 2 SO 4 at 20, 40 and 60 kg ha-1 levels of sulphur application. The utilization of sulphur applied at planting and that applied at panicle initiation were also studied in this experiment. The results showed that plant height and number of tillers were not significantly influenced by the levels of sulphur, sources of sulphur and their interactions. The leaf area index increased due to the application of sulphur at all the growth stages. The dry matter production increased with sulphur application. The increase in dry matter production due to the application of graded levels of sulphur was found to vary from 4 to 47 per cent.

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