| Sulfur is one of the necessary mineral elements of crops. Foreign researchers have studied the sulfur requirements and the growth and development responses to sulfur deficiency in wheat, especially the effects of sulfur fertilization on quality parameters such as grain protein composition and dough rheology. However, the systematic studies on how sulfur influenced the processes of photosynthesis and dry matter production, so that influenced the formation of yield and quality of wheat were rarely done at home and abroad. Therefore, a study was conducted on the Teaching and Demonstration Farm, Agricultural University of Hebei, Baoding, during 2001-2002, using high-quality cultivar 8901-11 and high-yield cultivar 4185 as materials. The object of this study was to clarify the effects of sulfur on yield and quality properties of wheat through determinations of photosynthetic performances, nitrogen metabolism and grain and quality parameters, so as to provide some experimental foundations for reasonable sulfur fertilization of wheat. The results were summarized as follows:1. Fertilizing different kinds of sulfur and in certain range of sulfur application (0~60 kg S hm-2), chlorophyll content (Chl), net photosynthetic rate (Pn) in the top leaves of wheat plants and in flag leaf and the third leaf from top all increased with the increase of sulfur fertilization. The population photosynthesis parameters were also improved by S fertilization. But for high sulfur treatment (90 kg S hm-2), the Pn and Chl for all leaves were lower than that of the middle sulfur treatment (60 kg S hm-2). This results showed that fertilizing more than 60 kg S per hm2 might influence the improvement ofphotosynthetic ability in the conditions of the trial soil (soil available S 10 mg kg-1). It can be concluded that reasonable sulfur fertilization improved individual and population photosynthetic performances, and this might be the physiological basis of the increasing grain yield by S fertilizing.2. Fertilizing different kinds of sulfur fertilizers and with the increasing of sulfur application (0-60 kg hm-2), nitrogen metabolism activities of wheat plants were enhanced. Compared with CK (0 kg hm-2), the key enzyme of nitrogen metabolism, nitrate reductase (NR), and soluble protein content in top leaves of wheat plants and in flag and the third leaf from top were increased by S fertilizing. The pre-anthesis nitrogen accumulation in vegetative organs such as leaves, stalks and husks (spikes excluding grains), the post-anthesis nitrogen translocation from vegetative organs to grains and the post-anthesis nitrogen absorption by wheat plants were also increased by S fertilization. The rude protein content in grains with S fertilizers was also higher than that without S fertilizers. These results showed that the increase of nitrogen metabolism activity of wheat plants owing to S application was the physiological basis of the improvement of quality parameters such as protein content.3. In a suitable range of sulfur application (0~60 kg hm-2), the grain yields of the two cultivars increased with the increasing sulfur fertilization, and the highest grain yield occurred for the middle sulfur treatment (60 kg hm-2). The yield of high sulfur treatment (90 kg hm-2) was decreased compared to that of the middle one. The changing tendency of the three yield components, spike number per hm2, grain number per spike, and 1000-grain weight, were similar to that of grain yield with the increase of sulfur fertilization. And also, grain yield and yield components were all enhanced by applying different kinds of sulfur fertilizers, i.e. ammonium sulfate, gypsum and element sulfur.4. The effects of different kinds of sulfur fertilizers on nitrogen metabolism were different. NR activities in the top leaves, flag leaf and the third leaf from top of the wheat plants fertilized with ammonium sulfate were highest among the three treatments fertilized with different kinds of sulfur fertilizers. Soluble protein content in flag leafwhich was the...
|
PDF Full Text Request