Browsing by Author "Mohan Kumar, B"

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    Effect of N, P and K on the yield of cowpea, variety P118
    (Kerala Agricultural University, 1979) Mohan Kumar, B; Balakrishna Pillai, P
    An experiment was conducted at the Instructional Farm of the College of Horticulture, Vellanikkara to study the effect of different levels of N, P and K on the yield of cowpea variety P-118. Nitrogen at 21.6 kg/ha was found to be the optimum level for maximum grain production. Optimum level of P could not be estimated since the crop exhibited a linear response beyond the maximum level tried. Applied K did not exhibit any significant influence on the yield components indicating the adequacy or soil supplies of the nutrient.
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    Initial viability and crop yields in cowpea (Vigna unguiculata L. Walp)
    (Division of Seed Technology, Indian Agricultural Research Institute, New Delhi, 1980) Mohan Kumar, B; Agarawal, P K
    An investigation was conducted at the Division of Seed Technology, Indian Agricultural Research Institute, New Delhi to study the effect of loss of viability on growth and yield of cowpea and to find out whether the deleterious effects due to loss of viability could be compensated by increasing the plant population per unit area. The treatments comprised of four levels of germinations (72, 63, 48 and 39 per cent) and two plant populations (20 and 40 plants/m2). The field experiment was laid out in a 4 x 2 factorial randomized block design with three replications. The crop was sown on 22nd of March, 1980 and harvested on 19th of July, 1980. The findings are summarized below: 1. In order to create variability in germination percentage accelerated ageing treatment was given. During accelerated ageing, seed deterioration was maximum between 2nd and 3rd week after treatment. There was no deterioration during the first week. The length of root, shoot and their dry weight did not vary much until 3rd week after treatment. However, there was a drastic reduction in these attributes during the 4th week. 2. The rate as well as total field emergence were inversely related to the seed deterioration. 3. Leaf area decreased with seed deterioration at the final phase of crop growth. Similarly the low population density was superior to the high one. 4. Regarding leaf dry weight, the control and the low population density were significantly superior to other treatments at the time of harvest. 5. Germination levels 72 and 63 per cent had significantly more stem dry weight per plant. Similarly the low population density registered higher dry matter accumulation in the stem. 6. The germination levels exerted no significant influence on plant height except at the final stage when control recorded the highest value. The effect of planting densities on height was also not markedly evident at any of the stages. 7. The low population density had invariably higher number of branches per plant at various stages of observation. Regarding the effect of germination levels, they were not statistically different. 8. Appearance of first flower was significantly earlier in the plants from deteriorated seed lots. The population density had no marked bearing on this aspect. 9. Total dry matter yield was highest in the plants from the maximum deteriorated seed lot during the early stage. However, at later stages the control plants accumulated maximum dry matter which was on par with the 63 per cent germination level. 10. Relative growth rate was least in the maximum deteriorated seeds in the beginning. But control registered the least value during the period between 45 and 103 days after sowing. The 63 per cent and 48 per cent germination levels were having significantly higher values at this stage. 11. The various yield components were not significantly influenced by the germination levels. However, population density had a marked bearing on the pod dry weight per plant and the dry weight of pod covers. 12. The low population density tended to increase the leaf nitrogen content at the final stage. However, the interaction effects were significant on the 45th day after sowing, with maximum leaf nitrogen content in the low population- 63 per cent germination combination. 13. With regard to stem nitrogen content, the control and 63 per cent germination level were significantly superior to other deteriorated lots at the final phase of crop growth. Similarly the plants of high density planting had remarkably more stem nitrogen than the low density. 14. Neither the germination level nor the population density did significantly influence grain nitrogen content. 15. Nitrogen uptake followed the same trend as that of total dry matter yield except in the case of total nitrogen uptake per hectare with reference to the population density. From this study, therefore, we may conclude that the four germination levels can be grouped into two distinct categories considering the loss of viability- yield relationships in cowpea. The control and the 63 per cent constitutes the first group, where no deleterious effects of seed deterioration was noted. The 48 and 39 per cent germination levels forms the second group where a significant reduction in terms of various growth attributes and dry matter yield was observed. This would, then, mean that the use of old seeds would not have a significant effect on yield, provided that viability is around 60 per cent and appropriate compensatory seed rates are used to allow for that fraction of seed population which is non- viable.
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    Nutrient requirements of pepper vines trained on live and dead standards
    (Kerala Agricultural University, 1981) Mohan Kumar, B; Abi Cheeran
    A trial was conducted at the Kerala Agricultural University Main campus, Vellanikkara, in orderto study the nutrient requirement of pepper vines grown on live and dead standards. It was found that dead standards significantly out-yielded the liveones. Also it was observed that for the dead standards, application of 75g N and 50g P203/vine/year would be the optimum.
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    Studies on the effect of phosphorus on the growth, yield and nurient uptake of two newly introduced rice varieties (Tainan 3 and Taichung Native I)
    (Division of Agricultural Chemistry, Agricultural College and Research Institute, Vellayani, 1967) Mohan Kumar, B; Koshy, M M
    To study the influence of phosphorus on the growth, yield and nutrient uptake of the two high yielding varieties of rice recently introduced into Kerala a pot culture experiment was carried out in randomised block design with 8 treatments and 3 replications. The varieties used were Tainen 3 and Taichung Native 1. The levels of phosphorus applied were 0, 40, 80 and 120 kg P205/ha in the form of superphosphate to over and above adequate amounts of nitrogen, potassium and other essential elements.
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    Studies on the interactive effects of water regimes, weed control treatments and nitrogen levels in direct-seeded rice
    (Faculty of the Post-Graduate School, Indian Agricultural Research Institute, New Delhi, 1984) Mohan Kumar, B; Singh, K N
    Field and green house experiments were conducted in the Division of Agronomy, Indian Agricultural Research Institute, New Delhi, during 1982 and 1983 to study the interaction of nitrogen x weed control x water regimes, on the growth, productivity and nutrient use pattern of direct seeded rice. The treatments in the field trails consisted of 4 levels of nitrogen (0, 50, 100 and 150 kg N ha-1). 3 weed control treatments (weedy check, butachlor, bentazone in 1982 and bentazone plus propanil in 1983) and 2 water regimes (continuously and intermittently flooded). The experiment was laid out in a split plot design, replicated thrice. The variables in the green house experiment were 2 rice cultivars (Pusa 33, drought susceptible and Pusa 312, drought tolerant), 3 nitrogen levels (0,100 and 200 mg N kg soil-1) and 5 soil moisture regimes (submergence to saturation, 0-0.025 MPa, 0-0.05 MPa, 0-0.075 MPa 0-0.10 MPa soil moisture tension).
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    Understorey productivity of agrisilivicultural systems as affected by tree population density and fertiliser regimes
    (Department of Silviculture and Agroforesty, College of Forestry, Vellanikkara, 1996) Joseph, Thomas; Mohan Kumar, B
    A split plot experiment, involving ailanthus (Ailanthus triphysa (Dennst.) Alston.) at various population densities (3333, 2500, 1600 and 1111 TPHA) and fertiliser regimes (0:0:0, 50:25:25, 100:50:50 and 150:75:75; kg N:P2O5: K2O ha-1 Yr-1), initiated in June, 1991 was intercropped with ginger (Zingiber officinale Roscoe). Additional treatments included monocultures of ginger and ailanthus. Objectives were to assess the productivity of ginger as a component of an agrisilviculture ststem involving ailanthus, besides analysing the partitioning of solar radiation among the different components of the system and characterising the nature of below ground interactions between the field and tree crop components. Ailanthus growth and its foliar chemical composition was not influenced by tree population density and fertiliser regimes. Light availability below the canopy was, however, strongly altered by tree population density. Availability of photosynthetically active radiation (PAR) was inversely proportional to stand density. Available PAR ranged from 35-72 per cent and 40-75 per cent of that in the open, at 50 and 150 cm above the ground level respectively. A strong relationship however, could not be established between light availability and foliar nitrogen content of the tree. Ginger grown in the interspaces of ailanthus exhibited better growth as compared to the sole crop situation. Tissue nutrient content of ginger in the later stages were higher when grown as mixed crop. The tree population density of 2500 trees per hectare (TPHA) registered better growth of understorey ginger. Fresh and dry rhizome yield of ginger also was maximum at this density. However, no strong relationship could be established between light availability and rhizome yield of ginger. Fertilisers applied to the tree component of the system, did not influence the growth, yield and quality of ginger. Three years of tree growth significantly reduced soil nutrient status below trees. A reduction in soil PH also was observed. Radiophosphorus recovered by ginger and ailanthus were not substantially altered by tree population density, lateral distance of application and cropping situation. However, ailanthus absorbed a substantial portion of the fertilisers applied to the ginger crop. Root activity of ailanthus suggests that 41-53 per cent of active roots are situated at about 40 cm from the tree trunk. Neighbouring trees in the high density stand registered a high recovery of 32P as compared to the low density stand, which may have important management implications.