Abstract

Evaluation of tolerance to phosphorus stress in cowpea (Vigna unguiculata L. Walp) in Cuba. II. Soil culture. This work evaluated the tolerance to P stress of eight genotypes of cowpea widely grown in Cuba, cultivating the plants in pots with soils subjected to several levels of available P. The results showed that employing the methodology of Cate and Nelson (1971), critical levels for maximal accumulation of N in the foliage were from 10 to 60 mg of P / kg of soil. The genotypes exhibited differences in yield potential, relative yield, response and consumption of P in order to accumulate N in the foliage, as well as in their capacity to produce roots and in the activity of the roots to extract P independently of the growth habit studied. The difference in N accumulated under low P between the diverse cultivars was due to variations in P use efficiency rather than to their ability to extract the element from the soil solution. Habana 82 and California Blackeyes V were the most promissory varieties for tolerance to P deficiency.