A sand culture experiment to compare the effects of sulphur on five wheat cultivars (T. aestivum L.)

A glasshouse sand culture experiment was conducted to determine the effects of sulphur supplied at 10,375 and 875µM concentrations on total dry matter production per plant (TDM), grain yield, harvest index (HI), yield components, nitrogen, sulphur and phosphorus levels in herbage and grain samples of two vitreous grained (Stockade and Gabo) and three non-vitreous grained (Insignia, Olympic and Summit) wheat cultivars (T. aestivum L.). Pelshenke doughball fermentation tests were done on wholemeal samples from all treatments.Stockade and Gabo had higher TDM than Insignia, Olympic and Summit at 10µM sulphur concentration, but relatively lower harvest indices. At 375µM sulphur, TDM increased for all cultivars; Gabo and Stockade continued to have relatively higher TDM, but Stockade produced only half the increase of any other cultivar. However, Stockade doubled its HI which, in turn, was double the increase recorded by Olympic and Summit. Insignia failed to increase its HI. Only Stockade showed increased TDM at 875µM sulphur. Olympic had the highest HI values at both 375 and 875µM sulphur. Similar grain yield increases for all cultivars were largely attained by differential grain number-grain size combinations. The higher sulphur supplies therefore stimulated the translocation of photosynthates to the developing grains and/or shifted the location of most rapid cell division from vegetative to reproductive sites. Stockade and Gabo had relatively higher percentages of grain sulphur at 10µM sulphur than the other cultivars and Stockade continued to have the highest percentage of grain sulphur at 375 and 875µM concentration. Except for a marked fall by Insignia, an increasing sulphur supply did not affect the distribution of sulphur within the plants as the indices for percentage sulphur remained largely unchanged. However, the distribution of nitrogen and phosphorus from straw to grain were both stimulated. Stockade and Gabo had relatively larger increases in their indices of percentage nitrogen, but the non-vitreous grained cultivars showed relatively larger increases in the percentage of nitrogen in the grain. Comparatively poor Pelshenke results, especially for Stockade, at I0µM sulphur, indicate an adverse affect of sulphur deficiency on grain quality. The experiment has shown that variation in sulphate sulphur supply differentially affected the biological and physico-chemical mechanisms controlling the optimum phenotypic expression of five wheat genotypes (cultivars). Part of these mechanisms involves close interrelationships and interactions between the uptake and/or metabolism of sulphur, phosphorus and nitrogen anions. Stockade was a particularly responsive cultivar to sulphur, while Insignia was relatively insensitive.