Leaf phosphorus and sorghum yield under rainfed cropping of a VertisolK LSahrawatauthorM HRahmanauthorJ KRaoauthorA field experiment was conducted at Patancheru, Andhra Pradesh in 1987-89 to study the response of sorghum cv. CSH 6 to fertilizer P (0, 10, 20 and 40 kg/ha) on a Vertisol low in extractable P. One sorghum crop was grown each year during the rainy season (June to September). Tissue samples from the newest, fully-developed leaf were collected at 50% flowering stage to establish the 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/ha. Leaf P concentration was linearly related to grain yield (r² varied from 0.724 to 0.993). The critical leaf P concentration at 90% of the maximum grain yield was about 0.25% P. Phosphorus content in the grain was not significantly correlated to yield.Sorghum1999KluwerArticle