Phosphorus Requirements of Rice Grown in Soils With Different Sodicity

Abstract

Phosphorus (P) fertilization is reported to alleviate the adverse effects of sodicity on survival of the seedlings, growth, and yield of rice. However, it is not known if required levels of Olsen's P to alleviate the adverse sodicity effects varies with increased sodicity stress. The present study, conducted at various pH values (8.0, 9.3, 9.7, and 9.9) with varying levels of P fertilization (P0.0, P0.2, P0.4, P0.6, and P0.8 kg hm −2 ), showed that P requirements of rice increased with increases in sodicity stress. At a pH of 8.0, 4.3 mg kg −1 Olsen's P was sufficient for survival of the seedlings, but not for grain weight (6.3 mg kg −1 ). Seedlings required 7.0 and 9.5 mg kg −1 Olsen's P to survive at pH 9.7 and 9.9, respectively. Similarly, high P levels were needed for more total and fertile tillers and spikelets numbers. One thousand (1000) grain weight and grain yield responded to 6.3, 7.7, 8.8, and 10.4 mg kg −1 Olsen's P at pH values of 8.0, 9.3, 9.7, and 9.9, respectively. Total chlorophyll in the leaves was significant in P fertilized plants. At a pH of 9.7, plants with 7.9 mg kg −1 Olsen's P had 52% more chlorophyll per 100 ppm sodium (Na) in the leaves compared to those at 6.3 mg kg −1 Olsen's P. This could possibly be due to improved tissue tolerance to Na in P-fertilized plants. Plants fertilized with P had higher P and potassium (K) concentrations in their shoots. Olsen's P levels of 7.7 mg kg −1 , 7.9 mg kg −1 , and 9.5 mg kg −1 were effective in restricting increases of Na (a potentially toxic ion) in shoots at pH 9.3, 9.8, and 9.9, respectively, thus helping plants have better yields.

Effect of salt and water stresses on growth, nitrogen and phosphorus metabolism in Cucumis sativus L. seedlings

“…Whereas, higher salt concentrations (100, 200 mmol·dm -3 NaCl) resulted in significant decline in phosphorus level in plant tissues. Some scientists have suggested that application of phosphorus might improve tolerance of plant to drought and salinity (Goutierrez-Boem and Thomas 1998; Kaya et al 2001;Burman et al 2004;Qadar and Ansari 2006).…”