| In order to clarify the effects of microelement fertilization and spring regulation measures on the growth and development, and the grain yield and quality of high-yielding winter wheat, two field experiments were carried out during 2010-2011 growing season in Gaocheng City, Hebei Province with a local commercial winter wheat cultivar Shixin828. The microelement fertilization experiment included four treatments, i.e., spraying water solutions of Zn, Fe and Se twice at jointing and pre-heading stages, with water spraying as control (CK). The experiment on spring regulation measures also included four treatments, i.e., all nitrogen (basal nitrogen excluded, the same as follows) topdressing at erecting stage (with irrigation, the same as follows) and Paclobutrazol spraying (N1); 2/3 nitrogen topdressing at erecting stage with Paclobutrazol spraying, and 1/3 nitrogen topdressing at jointing stage (N2); topdressing 1/3 nitrogen at erecting stage, and 2/3 at jointing stage (N3); all nitrogen topdressing at jointing stage (N4). The main results were summarized as follows.1. The yield of wheat sprayed with the three microelements were all increased compared with that of CK, especially the yield of Se treatment was significantly higher than that of CK. However, the yield components significantly optimized by each of the three microelements were different. The 1000 grain weight of Zn treatment, the spike number per m2 of Fe treatment, and the grain number per spike of Se treatment was the highest respectively in those of the four treatments, and significantly higher than that of CK, meaning that the yield increase by spraying of Zn, Fe and Se was achieved through the significant increase of grain weight, spikes per m2, and grains per spike, respectively.2. The Zn concentration in wheat grains of the treatment with Zn, and the Se concentration in wheat grains of the treatment with Se, was respectively the highest among all microelement treatments, and significantly higher than those of other treatments. The Fe concentration in wheat grains of the treatment with Fe, was also the highest among all treatments, and significantly higher than those of CK and the treatment with Se, but insignificant to that of Zn treatment. The grain protein contents of wheat sprayed with the three microelements were all increased compared with that of CK, but the difference of grain protein contents among all treatments including CK was insignificant.3. Comprehensively analyzing the microelement fertilization experiment, the three microelements play different roles in optimizing yield components and in increasing the concentrations of microelements in grains. The decision for microelements fertilization should be made according to actual limiting factors in wheat production. Under high fertility conditions, the effects of Fe to increase yield and quality of wheat could be substituted by Zn fertilization through foliar spray.4. The difference of spikes per m2 among different spring regulation treatments (N1~N4) was not significant. The grain number per spike of N1 was significantly higher than those of N3 and N4, but insignificantly higher than that of N2. The 1000 grain weight of N1 was significantly higher than that of N4, but the difference of 1000 grain weight among N1, N2 and N3 was not significant statistically. Because of the interaction of the three yield components, the grain yield of N1 was the highest, and significantly higher than those of N3 and N4. The results showed that, topdressing all nitrogen fertilizer with irrigation and regulating by spraying Paclobutrazol at erecting stage could obtain higher grains per spike and grain weight than those by simply topdressing of nitrogen with irrigation at jointing stage, and, therefore, obtain higher grain yield.5. The total culms of wheat of the treatment T1 at jointing stage was significantly higher than those of other treatments. Topdressing nitrogen at jointing stage with irrigation (N4) satisfied the nitrogen requirement thereafter, and the difference of spikes at maturity among the four treatments (N1~N4) was not significant. The LAI at jointing stage of wheat of the treatments N1 and N2 were higher than those of N3 and N4. But the LAI at booting stage of wheat of the treatments N3 and N4 increased, and higher than those of N1 and N2. The LAI of the four treatments (N1~N4) after anthesis were not significant, but the LAI of N4 was the highest among the four treatments. The dry matter accumulation of N1 at jointing stage was the highest, and that of N4 at booting stage was the highest among the four treatments. The post-anthesis dry matter accumulation of the four treatments was not statistically significant. That meant that, the pre-anthesis dry matter accumulation was affected, but the post-anthesis dry matter accumulation was little affected by different spring regulation treatments (N1~N4).6. The secondary roots at jointing stage of wheat of the treatments N1 and N2 were significantly higher than those of N3 and N4, but the secondary roots after booting stage of wheat among the four treatment (N1~N4) was not significantly different. The difference of plant height of wheat before booting stage was not significant among the four treatment (N1~N4). The plant height of N4 after booting, however, was always the highest, and significantly higher than that of N1. The basal internode diameter and the lengths of the four top internodes were not significantly different among the four treatment (N1~N4). But the basal internode of N4 was significantly longer than those of other treatments. The lengths of basal internode among the treatments N1, N2 and N3 were not significantly different. With the earlier nitrogen topdressing or topdressing more nitrogen at earlier growth stage, the number of sterile spikelet decreased, but those of fertile spikelet and grains per spike increased. And the number of sterile spikelet in N1 was significantly less than that of N4, but the number of fertile spikelet and grains per spike in N1 was significantly more than those of N4. The grain weight of N1 during the grain formation period after anthesis was usually higher than those of other treatments, and the 1000 grain weight of N1 at maturity was the highest among the four treatments (N1~N4). The 1000 grain weight at maturity was significantly lower than that of N1.7. The difference of chlorophyll SPAD values and photosynthetic rates in flag leaves of wheat with different spring regulation treatments (N1~N4) were insignificant statistically from booting to 20 days after anthesis. But the flag leaf chlorophyll SPAD values and photosynthetic rates of the treatments topdressing more nitrogen (N4å’ŒN3) increased significantly during late growing period of wheat.8. Comprehensively analyzing the spring regulation experiment, although the photosynthetic characteristics during late growing period of wheat of the treatments topdressing all or more nitrogen at erecting stage (N1 and N2) were less superior than those of the treatments topdressing all or more nitrogen at jointing stage (N4 and N3), the yield traits of N1 and N2 were superior to those of N4 and N3. The regulation strategy of nitrogen topdressing at erecting stage with Paclobutrazol spraying overcame the disadvantages of longer basal internode and taller plant height, so that avoided the danger of wheat lodging during later period. So that except the strategy of topdressing nitrogen and irrigation at jointing stage which is widely used in wheat production, the strategy of topdressing nitrogen fertilizer and irrigation with the regulation by Paclobutrazol spraying at erecting stage is also feasible based on the effect of the strategy on wheat yield traits, population and individual characteristics. |
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