Leaf phosphorus and sorghum yield under rainfed cropping of a Vertisol
1999
Sahrawat, K.L. | Rahman, M.H. | Rao, J.K.
Little attention has been devoted to the calibration of plant P tests for sorghum, especially under rainfed cropping although information is needed for developing an efficient P management strategy for increasing crop productivity. A field experiment was conducted for three years (1987-1939) to study the response of sorghum to fertilizer P (0, 10, 20 and 40 kg P ha(-1)) on a Vertisol, low in extractable P, at the ICRISAT Center, Patancheru (near Hyderabad), India. One sorghum crop was grown each year during the rainy season (June-September). Leaf tissue samples consisting of newest, fully-developed leaf, were collected at 50% flowering stage of the crop, for establishing relationship between leaf P concentration and grain yield. During the three years, sorghum grain yield and leaf P concentration increased in response to P application up to 40 kg P ha(-1) and the leaf P concentration was linearly related to grain yield (r(2) varied from 0.724 to 0.993). The critical leaf P concentration at 90% of the maximum grain yield was found to be about 0.25% P. Phosphorus content in the grain was not significantly correlated to yield.
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