PHOSPHORUS UPTAKE BY KALLAR GRASS [LEPTOCHLOA-FUSCA (L) KUNTH] FROM DIFFERENT DEPTHS IN SALINE AND NONSALINE SOIL

The uptake of P-32 by roots of Kallar grass [Leptochloa fusca (L.) Kun th] to assess P uptake from different depths was investigated in two s oils differing in salinity. The isotope was introduced at three depths (5, 15 and 25 cm) in the profile and uptake was assessed by P-32 reco very in the herbage on two successive harvests (LI 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 co nditions at the seedling stage and that tolerance increases during sub sequent growth. P concentrations in shoots were similar in plants from saline and normal soil at harvests I and II but markedly higher for t he saline soil at harvest III. Root P concentrations were also higher in plants grown in the saline soil than in those in the non-saline soi l. At harvest II, the uptake of P-32 by roots of Kallar grass decrease d significantly with depth in the saline sail, while it was greater in the 20-35 cm zone than in the upper profile at harvest m. In normal s oil, P-32 uptake was significantly greater in the upper 20 cm zone tha n the lower depth at harvest II, but it was similar throughout the pro file at harvest m. The results indicate that Kallar grass is capable o f maintaining P uptake under salinity stress. The species may extract substantial amounts of nutrients from deeper soil horizons and thus ca n thrive on low-fertility saline soils.