A Study Of Enhanced Ammonium Nutrition On Yield And Its Physiological Mechanism In Different Varieties Of Wheat

Field experiments were carried out to investigate the yield effect andphysiological mechanism in14winter wheat varieties in condition of the mixednitrogen ratios of NO₃^-/NH₄⁺at100:0（CK）,75:25（N₁）,50:50（N₂）,25:75（N₃）,0:100（N₄）respectively. Differences and classification of wheat in different growth periods inconditions of all the indicators were discussed. From2009to2011, based on the effectof enhanced ammonium nutrition （EAN） on early growth of wheat, dry matteraccumulation, characteristics of senescence, wheat yield including its components, andthe utilization rate of nitrogen in six main winter wheat varieties which are Zhengmai004, Zhengmai9023, Zhengmai366, Luomai23, Aikang58, Zhoumai22wereexplored. The main results are as follows:1. Depending on the results of early growth of wheat under EAN,14winter wheatvarieties were classified in sensitive type including Zhengmai004and Zhoumai22,sub-sensitive type including Luomai23and Aikang58, non-sensitive type includingZhengmai9023and Zhengmai366respectively. EAN effects of the different types ofwheat had significant difference. The results indicated that N₁and N₂couldsignificantly promote the early growth of three types. Plant height, leaf area index,tiller number per plant, dry weight increased significantly, while the root length, thedry weight of the underground part was not influenced significantly in sensitive andsub-sensitive type. EAN effects were different during different growth periods ofwheat. Tiller number of single plant and plant weight increased at regreening stage.LAI increased at jointing stage. But it showed unremarkable influence on tillering anddry weight of stem and sheath. at jointing stage.2. Under the EAN, soluble sugar content and soluble protein content varies withNO₃^-/NH₄⁺proportion different in flag leaf and grain. N₁treatment could promotesoluble sugar synthesis and accumulation in sensitive and sub-sensitive type, and the increasing of flag leaf soluble sugar content and the grain soluble sugar content keepsdynamic balance in the sensitive varieties, prompting the grain soluble sugartransforing into starch. At the early grouting stage, the flag leaf soluble protein contentshow a significant increase trend under the N₃, N₄treatment.Under the N₁treatment,soluble protein content show significant difference in all the wheat. the highest solubleprotein content appear at the end of the grouting in the sensitive wheat varieties, butthe time appear in the grouting later period in sub-sensitive and insensitive type. UnderN₁treatment, EAN increasing total starch content in sensitive type and sub-sensitivewheat, and significantly increasing the amylose content in zhengmai004, Zhoumai22,Luomai23.3. With treatment under EAN, different wheat varieties needed different suitableNO₃^-/NH₄⁺to increase production. Improvements of Zhengmai004and Aikang58reached significant level under N₁, Improvements of Zhengmai004and Aikang58reached significant level under N₁, Zhengmai366and Zhengmai9023reached thehighest yield under CK, while N₄substantially decreased the production of all thewheat varieties. N₁treatment increased the spike number, grain number and1000-grain weight of Zhengmai004, Aikang58and Luomai23. Zhengmai366andZhengmai9023had the highest spike number and the greatest grain number per spikeunder CK. Zhengmai366reached the highest1000-grain weight and the lowest spikenumber under N₄. Single nitrate nitrogen increased the HI and NHI of Zhengmai366and Zhengmai9023. The HI and NHI of Zhengmai004and Aikang58weresignificant under N₁, which showed that nitrogen utilization efficiency was improved.4、The effect of EAN on the aging characteristics of different wheat types hadsignificant differences. It could improve the chlorophyll content, SOD, POD activityin effect-sensitive wheat flag leaf, significantly reduced the MDA content and freeproline content, extended the functional period of wheat leaf and promoted the leavesto produce more photosynthetic products, thereby delayed flag leaf senescence, andincreased grain weight and production.