Productivity and P-use efficiency of clusterbean (Cyamopsis tetragonoloba) as influenced by bio-regulators and phosphorus

Abstract

A field experiment was conducted at Bikaner during 1999 and 2000 on sandy soil to study the effect of bio- regulators (thiourea and dimethylsulphoxide) and phosphorus on productivity and P-use efficiency of clusterbean [Cyamopsis tetragonoloba (L.) Taub.]. The study revealed that application of thiourea 5 kgtha in the soil (split), thio- urea 5 kgtha + dimethylsulphoxide 2 kgtha in the soil (split), foliar spray of 500 ppm thiourea and foliar spray of 500 ppm thiourea + 100 ppm dimethylsulphoxide proved effective in improving the growth and yield-attributing param- eters over the control. The maximum seed yield of 1.988 tonnestha was obtained with thiourea 5 kgtha ++ dimethylsulphoxide 2 kgtha in the soil (split) along with 17.2 kg Ptha, which was on a par with yield obtained with application of 5 kg thiouredha in soil (spilt) and 8.6 kg Ptha, and foliar spray of 500 ppmtha thiourea and 8.6 kg P/ ha. Growth indices, viz. leaf-area index (LAI) and crop-growth rate (CGR) also improved with bio-regulators and phosphorus application. Application of phosphorus up to 17.2 kg Ptha significantly improved the LA1 and CGR at 60 and 90 days after sowing (DAS), number of nodulestplant, podstplant and pod length as well as P-use effi- ciency. The gum content increased significantly due to phosphorus application up to 8.6 kg Ptha. The maximum P recovery of 47.4 kglha was obtained with the application of 8.6 kg Ptha followed by 17.2 kgtha (26.4 kgtha). The highest P uptake by seed (10.72 kgtha) was obtained with 5 kg thiouredha + dimethylsulphoxide 2 kgtha in the soil (split). Soil and foliar applications of thiourea and dimethylsulphoxide recorded higher agronomic as well as physiological efficiency of the applied phosphorus.