CHARACTERIZATION OF EFFECT OF PHOSPHORUS DEFICIENCY AND IT’S INTERACTION WITH NITRATE AND AMMONIUM ION SUPPLEMENTS IN RICE
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Date
2020
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Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G.)
Abstract
,Phosphorus, deficiency is a major constrains for rice production. On the other hand nitrogen deficiency severely affects rice growth and decrease yield. As demand of P and N fertilizers increasing continuously, development of tolerance to P and N nutrient deficiency would be more appropriate solution. Modification in rice root morphology and metabolic process under P deficiency also affects the uptake of other nutrients. Organic acid secreted by the rice root, converts organic P to plant available P (inorganic P) so that plant can easily uptake phosphorus. Activity of PM H+ ATPase increases under P deficiency which is coupled with citrate exudation. Increased activity of PM H+-ATPase is reported to result in increase in net uptake of NO3− and NH4+ (Vinicius et al., 2011). Hence it is important to characterize the interaction effect on rice root morphology and on genes related to PM H+-ATPase pump activity. Field evaluation of selected twenty four diverse rice genotypes indicating significant variation in plant height, number of tillers, biological yield and grain yield. Among twenty four genotypes, four genotypes were selected based on their performance under P deficient field condition and grown for 30 days in hydroponic culture under three treatment conditions i.e. P+N+ (N as ammonium sulphate), P-N- (N as ammonium nitrate) and P-N+ (N as ammonium sulphate). In hydroponic condition Sahbhagi Dhan performed well under both P and N ,deficiency stress as well as, under P deficient and N ,sufficient condition,. After 30 days, P was estimated from shoot and root tissue and we found that Sahbhagi Dhan showed maximum shoot P utilization under both P and N deficiency stress ,condition as well as under P deficiency stress,. Whereas maximum root P utilization was observed in Shenong under P-N- stress condition and in RRF-78 under P deficiency stress condition (P-N+). Hence based on hydroponic studies, Sahbhagi Dhan was considered as tolerant for both P and N deficiency stress. Whereas both Sahbhagi Dhan and Shenong were considered as tolerant for P deficiency stress (P-N+).
pH was measured and maintained after every two days of interval. Analysis on pH variation showed the treatment effect on genotypes. In Swarna, relatively stable pH was observed at 24th day in P-N+ condition as compared to the control and it showed the minimum effect of P deficiency whereas lower pH was observed at 27th day under P-N- condition. In case of RRF-78, non significant variation was observed in all the three treatment conditions. In Sahbhagi Dhan higher pH was recorded at 27th day under both P and N ,deficiency stress as well as, under P-N+ condition whereas in Shenong, more variation in pH was observed from 24th to 27th day under P-N- condition.
Gene expression analysis was conducted with four genes namely OsA3, OsA9, OsSPX1 and OsALMT in all the four genotypes under all the three treatment conditions. Almost all genes were expressed in Sahbhagi Dhan under both P and N deficiency stress as well as under P deficiency stress condition. The gene, OsA3 ,showed differential expression in, all the genotypes. It was not expressed in root tissue of Swarna under P+N+ condition whereas expressed under P and N ,deficiency, stress. OsA9 gene was less expressed in Swarna and RRF-78 under P+N+ condition whereas high expression of the ,gene was, observed under P-N- condition in both shoot and root tissue and multiple bands were observed indicating alternate splicing of the gene under nutrient stress condition. Almost equal expression of OsSPX1 gene was observed in all the four genotypes under all the three treatment condition. OsALMT gene was less expressed in shoot tissue of Shenong under both P and N deficiency stress.