Effect of Phosphorus Application on Clusterbean under Different Intensities of Water Stress

ABSTRACT

Response of clusterbean [Cyamopsis tetragonoloba (L.) Taub.] to phosphorus (P) application (0 and 40 kg ha⁻¹) under different intensities of water stress at the critical pre-flowering stage was studied in a pot trial by withholding irrigation for 0, 3, 6, and 9 days. Increasing stress intensity progressively decreased plant water potential (Ψ_plant), relative water content, levels of different leaf metabolites, photosynthetic rate, and nitrate reductase activity under both phosphorus (P) treatments. However, P-fertilized plants displayed higher photosynthetic efficiency, leaf metabolism, and enzyme activity than unfertilized plants, though decrease in plant water status was more in P-fertilized plants. Recovery upon rewatering was also more in P-fertilized than unfertilized plants with respect to all the parameters studied. Consequently, P application significantly enhanced dry matter and seed yields at all stress intensities. The results indicate the possibility of alleviation of water stress effects by P nutrition in clusterbean, at least up to moderate stress level.

Keywords:

• Cyamopsis tetragonoloba
• chlorophyll
• nitrate reductase
• photosynthesis
• relative water content
• seed yield