| The effects of plant density, the application amount and basal: top dressing ratio of nitrogen fertilizer on the characteristics of grain nutritional and processing quality formation and the relationship between carbon-nitrogen metabolism and grain quality of weak gluten wheat variety Ningmai 9 (Tr. aestivum L.) were studied on the experiment field of Crop Cultivation and Physiology Key Laboratory of Jiangsu Province, Yangzhou University in 2000-2002. The approach of quality control by cultivation techniques was suggested. The main results were as follows.1. The grain protein contents in all treatments showed a high-low-high change. Grain protein content kept high at primary stage of grain formation, then declined to the lowest on the 21st day after anthesis(DAA) at high N level, but on the 28th DAA at low N level, after which it gradually rose until maturity.2. At primary stage of grain formation, grain albumin and globulin contents were relatively high, then declined gradually with grain development, but globulin content decreased less. Gliadin and glutelin contents were low at primary stage of grain formation, then increased obviously after the 14th DAA until maturity. Glutelin was formed earlier than gliadin, but the rise rate was slower than that of gliadin, especially at middle and late stages of grain filling. At maturity gliadin and glutelin contents were significantly higher than albumin and globulin contents. The proportion of each protein component to total protein content had nearly the dynamic as that to grain weight. Albumin and globulin contents gradually went down during grain filling period while gliadin and glutelin contents rapidly increased after the 21th DAA, which suggested that albumin and globulin were mainly formed at the primary stage and gliadin and glutelin were mainly formed at middle and late stages.3. The contents and the accumulated amounts of amylose, amylopectin and starch in grains showed "S" type dynamics with grain development. The accumulation rate reached its peak on 21-28th DAA. The accumulating rate of amylopectin was obviously greater than that of amylose. Logistic equation could be used to match grain amylose, amylopectin and starch accumulation tendencies. Fast accumulation stage of amylopectin emerged earlier than that of amylose. Grain starch content was significantly negatively correlated to protein content at maturity, which satisfied the demand of improving grain quality of weak gluten wheat.4.Plant density, N applying amount and basal: top dressing ratio had significant effects on the contents of grain protein and components, starch and components and amylose/amylopectin ratio. Decreasing N applying amount or its rate after elongation stage or increasing plant density could obviously decrease protein content at middle and late stages of grain filling, mainly gliadin and glutelin contents, but slightly affect albumin and globulin contents. Decreasing N applying amount could increase amylopectin and starch accumulation rates from 14th to 35th DAA and amylopectin and starch contents from the 21th DAA to maturity, but decrease amylose content. Decreasing N application proportion after elongation stage could decrease the accumulation rates of amylose, amylopectin and starch from 14th to 35th DAA and amylose content, but increase the contents of amylopectin and starch at maturity. Increasing plant density could increase the accumulation rates of amylose, amylopectin and starch from 14th to 35th DAA and the contents and the accumulated amounts of amylose, amylopectin at maturity. Therefore decreasing N applying amount or its proportion after elongation stage or increasing plant density properly were beneficial to good quality and high yield.5.N content in plants reached its peak at the beginning of over-wintering, then gradually decreased with growth and development. Total soluble sugar content was high at over-wintering, booting stage and anthesis, but low at the jointing stage. The change of C/N ratio was similar to that of total soluble sugar cont... |
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