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 ( 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.

Effects of phosphorus application on photosynthetic carbon and nitrogen metabolism, water use efficiency and growth of dwarf bamboo ( Fargesia rufa ) subjected to water deficit

“…In our study, P application, to a certain extent, increased starch content of water-stressed dwarf bamboo (Table 3), possibly due to higher P n and/or an obvious decline in AMY activity. Similar findings have been described previously in Vigna aconitifolia and Cyamopsis tetragonoloba (Burman et al, 2009). Therefore, P application could tightly regulate starch synthesis and degradation under water stress to avoid periods of starvation.…”

“…Several studies have shown that P fertilization can directly enhance LRWC, as well as free and bound water components in water-stressed plants (Singh et al, 2006a;Sato et al, 2010). However, P application had minimal effect on LRWC of dwarf bamboo, regardless of water availability (Table 2), as also shown in previous studies of other crop species Singh et al, 2006b;Burman et al, 2009). Moreover, the LRWC of dwarf bamboo was influenced by water-P interaction (Table 6), which is due to interactive effects on leaf area Garg et al, 2004).…”

“…Statistics as in 2.72 ± 0.08 b 2.63 ± 0.06 b 3.00 ± 0.10 a 2.70 ± 0.04 a* Proline (mg g À1 DW) 0.41 ± 0.13 b 0.40 ± 0.10 b 1.88 ± 0.17 a 1.28 ± 0.10 a* confirmed in several plants (dos Santos et al, 2004;Garg et al, 2004;Burman et al, 2009;Sato et al, 2010). Meanwhile, some other reasons may have contributed to the improvement of P n after P application, including increased ATP and NADPH productions, activated enzyme activities in Calvin cycle, enhanced regeneration of sugar phosphate, higher output rate of photosynthates and cell proliferation (Rao and Terry, 1995).…”

“…Other studies have also indicated that P application can affect dry matter partitioning because plants invest relatively less C and N into roots and more into leaves, which can increase the rates of leaf relative growth and CO 2 assimilation per unit of leaf area, as well as carbohydrate contents (e.g. sucrose, soluble sugar and starch) (dos Santos et al, 2004;Burman et al, 2009). In addition, P fertilization can accelerate nitrate (NO À 3 ) reduction and ammonium (NH þ 4 ) assimilation and produce more nitrogenous compounds in water-stressed plants by promoting NO À 3 absorption and activation of enzymes (e.g.…”

“…Most soils, even fertile types, are deficient in P i as its uptake via root absorption is faster than its replenishment in soil solutions (Suriyagoda et al, 2011). Recent studies have demonstrated that P deficiency inhibits processes related to energy metabolism and biochemical synthesis, such as photosynthesis, respiration (especially the glycolytic pathway) and N fixation; P deficiency also reduces the activities of key enzymes involved in C and N metabolism dos Santos et al, 2004;Burman et al, 2009). Moreover, P deficiency causes aberrant root architecture in terms of number and density of lateral roots, and thus affects P i transport, which serves as a long-distance signal (Lin et al, 2014).…”