| Field experiments were conducted to investigate the super high yield mechanism of winter wheat with different maturing phases, premature senescence variety Xinong 979 and normal yellowing variety Yunong 416, in wheat growingseason of 2012-2013 and 2013-2014. The experiment was carried out at Henan Agriculture University Research farm, and designed with different basal/topdressing ratios of nitrogen fertilizer(N1, 10:0; N2, 7-3; N3, 5:5; N4, 3-7; N5, 0:10) on the condition of 240 kg pure nitrogen per hectare, to evaluate the effect of different basal/topdressing ratios of nitrogen fertilizer on leaf senescence, population quality, grain filling, grain yield and quality. The main results were as follows: 1.Effect of different basal/topdressing ratios of nitrogen fertilizer on leaf senescence of wheatThe results indicated that the chlorophyll content of the flag leaf increases with the increase of the topdressing proportion during the earlier growing stage. The chlorophyll content of the flag leaf increased with the growth period then descending. The treatment’s duration time of chlorophyll content rise is longer and falling slowly with larger topdressing proportion. N3 treatment has the highest chlorophyll content of Yunong 416,and the maximum of Xinnong 979 appeared in the N4 treatment. During the grouting, the differences of flag leaf’s net photosynthetic rate between each treatment are significantly and they all reached the highest in N5 treatment. There’s no obvious difference among N3, N4 and N5 treatments of Yunong416 at 35 d after anthesis, and N5 treatment of Xinong 979 have no significant difference with others at 40 d after anthesis. In the process of active oxygen metabolism, the activity of CAT, SOD and POD of the two cultivars are increased with the increase of nitrogen topdressing proportion. The enzyme activity of Xinong 979 are higher than Yunong 416 during 0-15 d after flowering, then decreased rapidly and less than Yunong 416 when 15 d after flowering. The content of MDA decrease with increasing the ratio of topdressing, MDA content of Yunong 416 increased rapidly at 35 d after anthesis, Xinong 979 rising rapid at 25 d after flowering and far greater than Yunong 416. 2. Effect of different basal/topdressing ratios of nitrogen fertilizer on population quality of wheatThe difference between the effects of topdressing nitrogen ratio on the population before winter and the highest population reached significant level, and the population reached largest at N1 treatment. For Xinong 979, the highest population of N1 treatment which nitrogen was applied as base fertilizer was higher than N5 treatment which all nitrogen fertilizer dressing about 45%-87.1%, is far greater than 18.9%-50.4% of Yunong 416. The percentage of productive tiller increase with the increase of the topdressing ratio. Increasing nitrogen application can improve the tiller percentage of Xinong 979 and more than Yunong 416, but the maximum of the effective panicle number is smaller than Yunong 416. Leaf area index increase with the increase of basal nitrogen proportion before the jointing stage, and reached the maximum value at the booting stage. The effect of base to dressing ratio of nitrogen fertilizer on leaf area index of Yunong 416 reached significant level before blooming stage, it’s significantly before the 20 d after flowering to Xinong 979 and it’s larger in N2 and N3 treatment after booting stage. The amount of dry matter accumulation first increased and then decreased with nitrogen topdressing rate increased in each period, and it reached the maximum in N3 treatment. The transport volume, transport efficiency and its contribution to grain yield of pre-flowering dry matter decreased with the topdressing nitrogen proportion increase. Top dressing with nitrogen can significantly increased the distribution in wheat grain, cob and glumes and the dry matter reaches a maximum at N3 treatment, decrease the allocation proportion of stem, leaf sheath and blades, conducive to the grain yield increase. 3. Effect of different basal/topdressing ratios of nitrogen fertilizer on the grain filling of wheatIncreasing N topdressing ratio can effectively increase the grouting time. For Yunong 416, topdressing fertilizer could significantly raise the filling duration of fast increase period, the grain filling rate at fast filling stage and slow filling stage and maximal filling rate, postpone the occurrence time of maximal filling rate, it have no significant effect of filling duration of each period. For Xinong 979, the treatment with topdressing nitrogen effectively increase the grain filling time of slightly increasing stage, the grain filling rate and time of slow filling stage and maximal filling rate, and the occurrence time of maximal filling rate had postponed. There were significant positive correlation between grain weight and the grain filling rate of fast filling stage and slow filling stage of Yunong 416, and it reached extremely significant level with the maximal filling rate. A significant positive correlation was observed between the grain weight and the filling duration, the filling rate of fast filling stage and the average grain filling rate. 4. Effect of different basal/topdressing ratios of nitrogen fertilizer on the grain yield and its components of wheatEffect of different basal/topdressing ratios of nitrogen fertilizer on grain yield reached significant level. The grain yield of normal maturity Yunong 416 was the highest at N3 treatment, high about 14.8%-44.36% than others. Early-senescent variety Xinong 979 had the highest yield at N4 treatment, and high about 8.5%-75.88% than others, its stimulation effect was significantly higher than Yunong 416. The appropriate topdressing nitrogen ratio can effectively increase ear number and grain number per panicle, and 1000-grain weight decreased. The ear number get the maximum value at N3 treatment, and the Yunong 416 greater than Xinong 979. The grain number per spike of Xinong 979 is larger than Yunong 416, the maximum of Yunong 416 appeared at N3 treatment and Xinong 979 at N4 treatment. The 1000-grain weight of the two cultivars both get the minimum at N3 treatment. 5. Effect of different basal/topdressing ratios of nitrogen fertilizer on grain quality of wheatRatios of basal/topdressing nitrogen fertilizer can effectively improve the quality of wheat. With the increase of the topdressing ratio, the protein content, wet gluten content and sedimentation value increased gradually, bulk density, water absorption, and hardness decreased, but the differences were not significant, the formation time, stability time and the maximum anti-extension resistance were first increased and then decreased. The formation time and the stability time of Yunong 416 reached the maximum at N4 treatment and the maximum anti-extension resistance in N3 treatment was the maximum. Its protein content, sedimentation value, bulk density, water content and maximum anti-extension resistance have reached the standard of strong gluten wheat, and the wet gluten content reached the standard at N5 treatment. The formation time, stability time and maximum anti-extension resistance of Xinong 979 were maximum at N3 treatment, and its protein content, wet gluten content, bulk density, water content, stability time and maximum anti-extension resistance all reached the standard of strong gluten wheat. The protein content and sedimentation value of Yunong 416 were higher than that of Xinong 979, and the wet gluten content and stability time were lower than that of Xinong 979. With the increase of nitrogen topdressing proportion, the main quality index of protein content, wet gluten content, sedimentation value and stability time of the two cultivars all increased, Yunong 416 increase higher than Xinong 979, and the wet gluten content and protein content were most obvious.In summary, nitrogen topdressing is beneficial to improve wheat yield and quality, but they didn’t have the same variation tendency. With the increase of the nitrogen topdressing proportion, the grain yield increased first and then decreased. The wheat quality continue to a smaller improve with the nitrogen topdressing proportion increase when the yield get the maximum. In order to achieve the goal of high yield and good quality, normal yellowing cultivar Yunong 416 appropriate N fertilizer applied ratio is 5:5 and premature senescence cultivar Xinong 979 appropriate basal/topdressing nitrogen ratio is 4:6 under the condition of 240kg/hm2. |
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