Effect of phosphorus deficiency on gas exchange characters and leaf greenness (spad) in soybean (Glycine max (L) merr.) genotypes
2015
Sathiakumar, K.P. | Vijayaraghavan, H.
Phosphorus (P) is a critical nutrient for plant growth and it makes up about 0.2% of a plant dry matter (Smith et al., 2011), but it is of the most difficult nutrient for plants to acquire. In soil, P may be present in a relatively large amount, but much of it is poorly available to plants due to its low mobility in the acidic soil. Low pH, aluminium (Al) toxicity, and low phosphorus (P) often coexist and are heterogeneously distributed in acid soils. To date, the underlying mechanisms of crop adaptation to these multiple factors on acid soils remain poorly understood. In this study, we found that phosphorus addition to acid soils could stimulate Al tolerance, especially for the P-efficient soybean genotype. The present study was aimed to screen 15 soybean genotypes for low P stress tolerance at flowering stage under normal soil (pH 7.0) and acid soil (pH 4.7) condition. The accessions BRAGG, AMS 2005–13 and MACS 1394 were found to be tolerant followed by accessions AMS 2010-6 and KBS 22–2009 observed to be susceptible based on gas exchange parameter and leaf greenness index (SPAD). BRAGG and MACS 1394 recorded higher photosynthetic rate compared to other genotypes. This confirms that these physiological traits can be used to screen soybean genotypes for low P stress under acid soil conditions.
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