Forage production and nitrogen nutrition in three grasses under coconut tree shades in the humid-tropics     

C.?B.?PandeyEmail author  S.?K.?Verma  J.?C.?Dagar  R.?C.?Srivastava 《Agroforestry Systems》2011,83(1):1-12

Reduction in forage production (FP) under trees in the humid tropics is well known, but information on how different levels of nitrogen (N) fertilizer influence FP under trees is meager. The present study reports effects of four N fertilizer levels (0, 60, 80 and 120 kg ha⁻¹ N) on net soil N mineralization rate (NMR) and soil moisture (SM), FP, shoot biomass/root biomass ratio (SB/RB), N concentration in SB, N uptake and nitrogen use efficiency (NUE) of three grasses [guinea (Panicum maximum Jacq.), para (Brachiaria mutica (Forssk) Stapf) and hybrid-napier (Pennisetum purpureum Schumach.)] under three canopy positions [under canopy (UC, representing high shade), between canopy (BC, representing low shade) and open] of coconut trees (Cocos nucifera L.) in a coconut based silvopastoral system in the humid tropical climate of South Andaman Island of India. The study was performed for two annual cycles (2005–2006 and 2006–2007). The hypotheses tested were: (1) FP would decline under tree shades, both in N fertilized as well as no N fertilized conditions, when SM was not growth limiting in the open. However, amount of decline in the FP would depend on grass species and intensity of shades i.e., higher was the shade greater would be the decline; (2) N fertilizer would increase FP under tree shades, but the increase depended on grass species, intensity of shades and amount of N applied. Amount of N applied, however, would not annul the shades effects when SM was not growth limiting in the open. The study revealed that the tree reduced light 59% under UC and 32% under BC positions, but the N fertilizer levels increased NMR by 11–51% under UC and 3–44% under BC positions compared to the open. SM did not differ across the canopy positions. Under all situations, FP of all grasses declined under UC (47–78%) and BC (18–32%) positions compared to the open; the decline was greater in Hybrid-napier than Guinea and Para grasses. Forage production of all grasses increased with N fertilizer increments under all canopy positions reaching 32 t ha⁻¹ dry matters for hybrid-napier at 120 kg ha⁻¹ N in the open. Both guinea and para grasses outyielded hybrid-napier grass under UC but not under BC or in the open. N concentration in the forage (SB) also increased as N fertilizer level increased. These observations support our hypotheses and suggest that forage production under coconut palms can be increased by the application of N fertilizer with both guinea and para grasses being more productive than hybrid-napier grass under the high shade. Where light conditions are better, hybrid-napier would produce more forage than the other species.  相似文献   

Salt Tolerance of Some Oats (Avena sativa L.) Varieties at Germination and Seedling Stage     

O. P. S. Verma  R. B. R. Yadava 《Journal of Agronomy and Crop Science》1986,156(2):123-127

Soil salinity is the serious problem of the arid and semi-arid tracts of the world. It causes great losses to agriculture by lowering the yields of various crops. However, such soil may be utilized either after reclaimation or by growing tolerant plant species. The degree of salt tolerance varies not only with plant species but the different varieties of the same species show variation in salt tolerance. Germination and seedling stages have a bearing on plant development at later stages of growth and ultimately crop yield. Therefore, in the present investigation, twelve varieties of oats viz., Colabagh, Kent, JHO-801, JHO-802, JHO-810, JHO-815, JHO-816, S-3021, S-2688, Chauripatti, UPO-201 and Sierra were tested for their relative salt tolerance to increasing levels of salinity in those combination of salts which nearly exist in the natural salt affected soils. Seeds were sown in petri dishes and were exposed to five salinity (40, 80, 120, 160 and 200 me/L. of salts) levels. The germination percentage, root and shoot length and dry weight of the seedlings decreased with increase in salinity. In general, varieties JHO-815, JHO-802, JHO-816 and UPO-201 were found to be more tolerant at germination and seedling stages.  相似文献   

Fuel and fodder from village woodlots: A Gujarat (India) experience     

D. P. S. Verma 《Agroforestry Systems》1988,7(1):77-93

Having attained self-sufficiency in food production, India is now concentrating in using wastelands to increase its production of other products of agroforestry namely, fodder, fuel and small timber for the poorer section of society. Many agroforestry practices are being tried towards the attainment of this goal. In one such attempt, a 4 ha plantation was established in 1974 on Community grazing land in the village of Dhanori in Gujarat as a part of the State Village Forests Scheme. Casuarina equisetifolia was planted beca se it suited the site and because the villagers wished it. Grasses grew up naturally as a result of the enclosure. The trees were felled in 1983–4 and the distribution of benefits determined by the village panchayat. The internal Rate of Return was 35%. Villagers benefited from grasses, fuelwood and small timber for house construction and repair and from the employment generated. The success of the project led the village to organize itself into a Tree Grower's Society and undertake further planting in 1985–6. The demonstrated efficiency of the woodlot let to 200 ha of other plantations being established in the area. the poor benefited considerably from the project but if they had a greater say in the deliberations of the panchayat, the benefits could have been even greater. this agroforestry system has the potential of increasing the production of grasses, fuelwood, small timber and fruits (food) from wastelands.  相似文献   

Hormonal influences in motility of canine uterine horns     

O P Verma  G A Chibuzo 《American journal of veterinary research》1974,35(1):23-26

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Nitrogen Dynamics Under Long Term Lantana Camara (L.) Residue and Fertilizer Application in a Rice-Wheat Cropping System     

Sandeep Sharma  T. S. Verma 《Journal of plant nutrition》2014,37(11):1804-1816

Long term effects of lantana (Lantana camera L.) residue and fertilizer application were studied on nitrogen (N) fractions in a Typic Hapludalf under rice-wheat cropping at Palampur, India (32°6’N, 76°3’E). After 12 crop cycles, lantana and fertilizer application showed an additive effect on the buildup of different N fractions. Hydrolyzable-N constituted 86% of total organic-N and 84% of total-N. All fractions of N except unidentified-N, non-hydrolyzable-N, and total-N were strongly interdependent and had a positive influence on grain yield and N uptake in rice and wheat crops. Serine+threonine-N was the most important fraction contributing towards grain yield and N uptake in rice and wheat. Fertilizers at 66% of recommendation plus lantana at 10 t ha^?1 maintained higher available-N than that under 100% fertilizers alone; the N content was same as 12 years before. Inclusion of lantana indicated net saving of 33% fertilizers plus higher yields and sustained soil health.  相似文献   

Expression of the c-fos gene and of an fos-related gene is stimulated by platelet-derived growth factor   总被引：92，自引：0，他引：92  

B H Cochran  J Zullo  I M Verma  C D Stiles 《Science (New York, N.Y.)》1984,226(4678):1080-1082

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A Cretaceous hoofed mammal from India     

Prasad GV  Verma O  Sahni A  Parmar V  Khosla A 《Science (New York, N.Y.)》2007,318(5852):937

The sedimentary record documenting the northward drift of India (Late Cretaceous to late Early Eocene) has recently provided important clues to the evolution, radiation, and dispersal of mammals. Here, we report a definitive Late Cretaceous (Maastrichtian) archaic ungulate (Kharmerungulatum vanvaleni genus et species nova) from the Deccan volcano-sedimentary sequences exposed near Kisalpuri village in Central India. This find has important implications for the origin and diversification of early ungulates and raises three possible paleobiogeographic scenarios: (i) Archaic ungulates may have been cosmopolitan in distribution. (ii) Kharmerungulatum might be an immigrant from Western Asia. (iii) Archaic ungulates may have originated in India.  相似文献   

Relation between specific gravity,starch and nitrogen content of potato tubers     

S. C. Verma  T. R. Sharma  K. C. Joshi 《Potato Research》1975,18(1):120-122

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Sucrose accumulation during high-temperature storage of potato tubers     

S. C. Verma  T. R. Sharma  S. M. Varma 《Potato Research》1974,17(2):224-226

Summary Potato tubers stored in a farm store from April to October (monthly average temperature between 24.7 and 36.2°C) accumulated considerable quantities of total sugars. Sucrose was the main component though in the variety Kufri Chandramukhi reducing sugars accumulated in amounts equal to sucrose.  相似文献   

Surface energy balance model of transpiration from variable canopy cover and evaporation from residue-covered or bare soil systems: model evaluation     

Luis Octavio Lagos  Derrel L. Martin  Shashi B. Verma  Suat Irmak  Ayse Irmak  Dean Eisenhauer  Andrew Suyker 《Irrigation Science》2013,31(2):135-150

A surface energy balance model (SEB) was extended by Lagos et al. Irrig Sci 28:51–64 (2009) to estimate evapotranspiration (ET) from variable canopy cover and evaporation from residue-covered or bare soil systems. The model estimates latent, sensible, and soil heat fluxes and provides a method to partition evapotranspiration into soil/residue evaporation and plant transpiration. The objective of this work was to perform a sensitivity analysis of model parameters and evaluate the performance of the proposed model to estimate ET during the growing and non-growing season of maize (Zea Mays L.) and soybeans (Glycine max) in eastern Nebraska. Results were compared with measured data from three eddy covariance systems under irrigated and rain-fed conditions. Sensitivity analysis of model parameters showed that simulated ET was most sensitive to changes in surface canopy resistance, soil surface resistance, and residue surface resistance. Comparison between hourly estimated ET and measurements made in soybean and maize fields provided support for the validity of the surface energy balance model. For growing season’s estimates, Nash–Sutcliffe coefficients ranged from 0.81 to 0.92 and the root mean square error (RMSE) varied from 33.0 to 48.3 W m^?2. After canopy closure (i.e., after leaf area index (LAI = 4) until harvest), Nash–Sutcliffe coefficients ranged from 0.86 to 0.95 and RMSE varied from 22.6 to 40.5 W m^?2. Performance prior to canopy closure was less accurate. Overall, the evaluation of the SEB model during this study was satisfactory.  相似文献