ALBERT

Description: SummaryExperiments made over a period of 3 years (1971–73) at Pantnagar, India, on the effect of plant density and spatial arrangement of a hybrid variety of maize (Ganga 2) and a local cultivar (Rudrapur) indicated that a density of (at least) 75000 plants/ha is necessary to obtain maximum grain yield. With increasing density from 25000 to 75000 plants/ha the date when 75 % of plants were silking was delayed 2–5 days and the percentage of barren plants increased from 1·7 to 28·7. In dense stands, grain yield of the hybrid variety was less affected by increasing row width from 60 to 90 cm than it was in the local cultivar.The average increase in yield with narrow (60 cm) row width as compared with wider (75 cm) row width was 6.8 % and it is argued that, in the context of the national need for increased food production, this increase cannot be overlooked.

Description: SummarySixty families of each of two tomato triple test crosses (S 120 × EC 61747 and EC 31513 × Pusa Ruby) were raised in completely randomized blocks in two replications with two fertilizer levels. Perkins & Jinks' (1971) analysis was used to detect and measure the interactions of additive, dominance and epistatic effects of genes with micro- and macro-environments for flowering time, maturity period, number of branches, final height, number of locules, number of fruits per plant, yields per plant and weight per fruit. Additive and dominance gene effects were almost equally sensitive to micro- and to macro-environments. The j and l type epistasis was more sensitive to the environments than the i type epistasis.

Description: SUMMARYIn order to examine whether high yield of maize could still be maintained at high plant densities by creating an ‘erectophile canopy’ through artificial defoliation of laminae, an experiment at Pantnagar, India, was made on the effect of density, stage and degree of defoliation in two divergent seasons, Kharif (rainy) and spring, of the year 1972. The defoliation treatments were either partial (clipping off the apical half of individual leaves) or complete (full leaf removal) and were imposed at three stages of plant growth, namely when 10 or 16 leaves were fully open or 12 days after silking. These treatments were applied at two plant densities, 60000 and 90000 plants/ha.Grain yield of maize increased significantly with the increase in population density in the spring season. The trend was diametrically opposite in the Kharif season. Defoliation at the 10th fully open leaf stage produced more grains than defoliating 12 days after silking, which in turn produced more than defoliating at the 16th fully open leaf stage, when plants were in full bloom. Increase in the degree of defoliation at the latter two stages of plant growth reduced grain yield, the effect being more at the 16th leaf stage. However, 50% defoliation at the 10th leaf stage increased grain yield in the Kharif season.The percentage protein content of grain declined with the increase in population density whereas increase in degree of defoliation increased the grain protein content. Higher protein content of grain was recorded in the spring than in the Kharif season. The leaf protein decreased as the plants neared maturity, especially at the higher degree of defoliation treatments.Sucrose and reducing sugars declined significantly with the increase in degree of defoliation. The reduction in sucrose was large enough to account for the reduction in total sugar percentage. Similar trends were observed in the sugar-to-protein ratio.

Description: SUMMARYData are presented from an experiment made in two crop seasons, to examine the effects of plant density and degree of defoliation at different stages of growth in maize at Pantnagar, India, on the dry-matter accumulation in different plant parts, leaf area index (LAI), time of silking and grain yield components.Different patterns of dry-matter accumulation in various plant parts was observed. Silking was delayed by increasing plant density. Defoliation (even partial) at the 16th fully expanded leaf stage resulted in substantial reduction in LAI and such yield components as number of ears, ear length, ear diameter and 1000-grain weight. On the other hand, partial defoliation done at the 10th fully expanded leaf stage to simulate an ‘erectophile canopy’ led to yield increases even under high plant density (90000 plants/ha) in the Kharif (rainy season), mainly through an increase in number of ears, 1000-grain weight and grain to stover ratio coupled with a reduction in barrenness and percentage of lodging. It is suggested that an increase in the photosynthetic efficiency per unit area of leaf resulting from the ‘erectophile canopy’ is the reason for these effects.

Description: SummaryIn a field experiment conducted from 1981 to 1984 on alluvial soil (Ustochrept) of Jalandhar, green manure (GM) of dhaincha, sannhemp, pearl millet and moong did not affect tuber yield in the 1st year but increased it in the 2nd and 3rd years. GM of dhaincha and sannhemp were more effective than the moong in reducing responses of potatoes to K. GM of pearl millet was as effective as the dhaincha or sannhemp in 1981–2 and 1982–3 when buried 55 days after sowing but was inferior in 1983–4 when buried 85 days after sowing and resulted in reduced concentrations of N and P in potato plants. GM of dhaincha, sannhemp and pearl millet increased concentration of K in potato plants and available K in soil. GM of dhaincha and sannhemp, in particular, increased soil available K by decreasing non-exchangeable K whereas GM of pearl millet increased soil available K without affecting non-exchangeable K.

Description: SummaryThe results of a long-term field experiment conducted from 1977 to 1984 on alluvial (Ustochrept) soil of Jalandhar showed positive responses of the crops to N. The responses of potatoes to N were reduced by farmyard manure (FYM), green manure of dhaincha and moong and the responses to the organic manures were also reduced by N. The N responsesof potatoes were, however, not affected by the N applied to preceding maize. FYM was better than the green manures in augmenting total tuber yield, large-grade tuber yield and K concentration in the plants.The N applied to the potatoes showed significant residual effect on succeeding wheat crops, reducing its optimum dose of N by about 50%. The residual effect of N on wheat was highly correlated with nitrate status of the soil. The organic manures applied to potatoes improved the yield of the succeeding wheat but did not differ from each other.The fodder crop of pearl millet raised after 7 years also indicated the superiority of FYM to the green manures. There was a build-up of organic carbon, N, P and K in soil and the build-up was maximal with the use of FYM. The application of N had no effect on the organic carbon and nitrogen status of the soil. N improved the availability of P but decreased that of K.

Description: A field experiment lasting 9 years was initiated in 1987 to study the effect of integrated nutrient management involving incorporation of wheat straw (WS) or farmyard manure (FYM) alone or in combination with inorganic fertilizer on a fine loamy mixed hyperthermic udic Ustochrept. Soil physical properties and the productivity of a rice–lentil cropping sequence were examined in a dry land farming system.At the end of the ninth cropping season, addition of organic materials had increased organic carbon, aggregate stability, moisture retention capacity and infiltration rate of the surface soil while reducing the bulk density. Application of inorganic fertilizer alone decreased the stability of macro aggregates and moisture retention capacity but increased the bulk density values. Treatment effects on moisture retentivity were more pronounced in the higher (0·3–1·5 MPa) suction range. During the first six experimental years, sole application of inorganic fertilizers produced 10–17% higher grain yield of rice, compared to sole application of organic sources or combined organic and inorganic sources. Annual applications of wheat straw and farmyard manure gave higher grain yields of rice from the seventh year onwards. Grain yields of lentil were higher with organic sources either alone or combined with inorganic nutrients.

Description: SummaryThe effects of differing degrees of leaf removal was studied in maize at different stages of growth and in varying plant densities. In control (untreated) plants significantly lower grain yield/unit area at the higher density (90000 plants/ha) was associated with greater barrenness, percentage of lodging and time taken for silking. Increase in plant density from 60000 to 90000 plants/ha led to a reduction in length and diameter of the ear and in weight of 1000 grains. Delay in the time of leaf removal from the tasselling stage until 10 days later increased yield, number of ears, ear length, diameter and test weight and decreased percentage of barrenness and lodging.Leaf removal adversely affected yield and yield components (number of ears, percentage of lodging, ear size and test weight of 1000 grains). Complete leaf removal at tasselling time delayed silking and reduced lodging.

Description: SUMMARYExperiments made over a period of 2 years (1975–6) covering three crop seasons at Pantnagar, India, on the comparative utility of intercropping the principal maize crop with legumes in economizing fertilizer N requirements of the former, indicated that among soya bean, cowpea, pigeonpea and groundnut, soya bean was the most suitable. At 40 kg N/ha intercropping maize with soya bean gave 19·5% more yield than taking it as a pure crop. When the option to use adequate fertilizer N does not exist, as is invariably the case with the average Indian farmer, intercropping maize with legumes, such as soya bean, is the logical way out. All the intercropping treatments left sufficient residual fertility to significantly increase yield of a wheat crop given no fertilizer which followed maize.