Phosphorus uptake by Kallar grass [Leptochloa fusca (L.) Kunth] from different depths in saline and non-saline soil

Abstract

The uptake of 32P by roots of Kallar grass [Leptochloa fusca (L.) Kunth] to assess P uptake from different depths was investigated in two soils differing in salinity. The isotope was introduced at three depths (5, 15 and 25 cm) in the profile and uptake was assessed by 32P recovery in the herbage on two successive harvests (II and III) after the initial establishment period (harvest I).At harvest I, biomass yield of Kallar grass was lower in the saline soil than in the normal soil. It is shown that this crop has a relatively low tolerance to saline conditions at the seedling stage and that tolerance increases during subsequent growth. P concentrations in shoots were similar in plants from saline and normal soil at harvests I and II but markedly higher for the saline soil at harvest III. Root P concentrations were also higher in plants grown in the saline soil than in those in the nonsaline soil.At harvest II, the uptake of 32P by roots of Kallar grass decreased significantly with depth in the saline soil, while it was greater in the 20–35 cm zone than in the upper profile at harvest III. In normal soil, 32P uptake was significantly greater in the upper 20 cm zone than the lower depth at harvest II, but it was similar throughout the profile at harvest III.The results indicate that Kallar grass is capable of maintaining P uptake under salinity stress. The species may extract substantial amounts of nutrients from deeper soil horizons and thus can thrive on low-fertility saline soils.