Evaluation of groundnut genotypes for phosphorus efficiency through leaf acid phosphatase activity

Abstract

Phosphorus (P) sources are limited around the globe making it unsustainable with present farming practices. This necessitates the development of more phosphorus efficient crops while monitoring P status. Groundnut (Arachis hypogaea L.) is a major crop in Southern Andhra Pradesh, India where soils are light textured and less fertile. Twenty groundnut genotypes were evaluated under a pot culture experiment conducted at Regional Agricultural Research Station, Tirupati, Andhra Pradesh, India during kharif, 2016 grown using standard crop recommended practices in P-sufficient (control) and in P-deficient conditions. Leaf Acid phosphatase activity and leaf P content were monitored after 60 days of sowing while kernel P and pod yields were recorded at harvest and estimated using standard protocols. Results showed that under P deficient conditions, genotypes TCGS 1616, TCGS 1622, TCGS 1624, TCGS 1517 and Greeshma had higher leaf P accumulation (between 0.20 % to 0.24 %) in comparison to others. Genotypes TCGS 1616, TCGS 1624, and TCGS 1517 reported high kernel P when compared to others under P starved conditions. Likewise under deficient soil P conditions, TCGS 1528, TCGS 1624, TCGS 1517 and Greeshma (range 2.71-4.45 µmoles hr-1g-1) demonstrated having lower leaf acid phosphatase content in leaves when compared to other genotypes. Only TCGS 1624, TCGS 1616 and Greeshma had lower leaf acid phosphatase while at the same time having higher accumulation of leaf P and highest pod yield followed by TCGS 1517 suggesting that P starvation was better coped by these genotypes and hence can be recommended in soils deficient in P. Leaf acid phosphatase activity correlated negatively with P content in leaves (r = -0.73) similar to those reported for soybean cultivars in Brazil. There is potential for breeders in accelerating identification of markers to specific traits that would be suitable for monitoring P status and manage nutrient application.