B. S. Sekhon

Phosphorus Nutrition and Nitrogen Assimilation in Chickpea (Cicer arietinum L.)

Summary Assimilation of nitrogen and phosphorus was studied in chickpea ( Cicer arietinum L. cv. GL-769) plants grown in pots under different P levels: Control (P 0 ), 7.5 μg Pg -1 soil (P 1 ) and 15.0 μg Pg -1 soil (P 2 ). Both P 1 and P 2 levels increased nodule nitrate reductase (NR) activity per plant and leaf NR activities at 51 (pre-flowering) days after sowing (DAS). At 88 DAS (flowering stage), nitrogenase (N 2 ase) and nodule acid phosphatase (APase) activities were stimulated by P application while NR activity decreased in the leaves. Root P and leaf P increased due to P 1 and P 2 levels at 71 DAS while only root P increased at 88 DAS. At 106 DAS (post-flowering stage), both P levels increased leaf NR activity and the concentrations of total N, chlorophyll (Chl) and sugars in leaves, suggesting improved translocation of reduced N from leaves to pods, which is needed for protein synthesis at this stage.

Phosphorus assimilation i mycorrhizal moong (Vigna radiata L.) plants under different phosphorus levels

Abstract Influence of phosphorus on its assimilation was studied in a pot experiment at two growth stages at different phosphorous (P) levels control (P 0 ), 10 μg P g −1 soil (P 10 ) and 20 μg P g −1 soil (P 20 ) in non-mycorrhizal (NM) and mycorrhizal (M) moong plants. The response of M plants to P application varied both with growth stage and P level. In NM plants, total P, shoot fresh weight (FW) and exopoly-phosphatase (ExoPase) activity in roots was enhanced with both P levels while root peroxidase and acid phosphatase activities (APase) in leaves increased with P 20 level only. Ester P, root FW, inorganic phosphate (P i ) and APase activity in roots were not affected at P 10 level. Total P and P i in leaves were enhanced with MP 10 but were unaltered with MP 20 treatment at 38 days after sowing (DAS). ExoPase and peroxidase activities increased but total P in leaves decreased with MP 10 and MP 20 plants at 50 DAS. APase activity and ester P in leaves increased with MP 20 while Chl concentration decreased at 38 as well as 50 DAS. Soil available P increased with both levels in M plants but only with P 20 with NM plants. The comparison of M and NM plants showed that M plants had greater P i at both samplings whereas root total P and Chl only at 50 DAS at each P level. Shoot FW and root ExoPase activity were greater in M plants with P 0 and P 10 levels. NM plants accumulated ester P more in roots while M plants in leaves at 50 DAS.