Effects of lime and phosphate on growth and nutrient uptake of lowland rice (Oryza sativa L.) varieties on an acid sulfate soil [Philippines]
1985
Singh, S.
Liming this acid sulfate soil proved not beneficial in both pot and field experiments and adversely affected the yield components and grain yield of all varieties studied. Phosphate additions resulted in improved plant growth and higher nutrient uptake of P, Ca, Mg and Mn in the pot experiment but only P, Ca and Mn from the field experiment determined at six weeks after transplanting. Phosphate additions depressed the ratio of (K + Mg) to Ca and N and K tissue concentrations from both pot and field studies. Root growth was enhanced with phosphate additions in all varieties. Grain yield increases from 18.4 and 28.2% over that of the control were obtained from additions of 200 kg P2O5/ha alone in all varieties from the pot experiment. Variety IR46 as well adapted to acid sulfate conditions and produced the highest grain yield among the varieties studied in both pot and field experiments, while IR4683-54-2 produced more straw and the lowest grain yield. The grain yield of IR 26 and IR 45 was 15 to 22% lower from that of IR 46 in all treatments in the field due to a lower percent filled spikelets. Variety IR 46 showed a higher Ca and Mn tissue concentration and a lower ratio of (K + Mg) to Ca than IR 26 and IR 45 at both sampling times from the pot experiment. Varietal differences in tolerance to acid sulfate condition could be due to differences in uptake of P, Ca and Mn as well as a balance between (K + Mg) and Ca in the tissues. Phosphate additions improved uptake of these nutrient elements and provided a favorable ratio of (K + Mg) to Ca on this particular acid sulfate soil which resulted in increased yields
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