| 1 Differences in quality of different type wheat cultivars and the relevant physiological basisFifteen different type cultivars were selected to study physiological mechanism of quality formation using physiological and biochemical analysis method. The principal results were as follows.1.1 Differences in protein quality of different type wheat cultivars and the relevant physiological basis1.1.1 Classification of different wheat cultivars based on protein qualityBased on glutenin content,, gluten content, and dough stability time, fifteen cultivars were classified into three groups: high glutenin content group (Groupâ… ), including Jimai20, Yumai34, GC8901 etc 7 cultivars, medium glutenin content group (Groupâ…¡), including Jina17, Zimai12,Yannong15 etc 4 cultivars, low glutenin content group (Groupâ…¢), including Yaishan 23, Ningmai9, Yangrnai9 etc 4 cultivars.1.1.2 Differences of protein and its component content in wheat kernel of different groupsCompared with three groups, there were no marked difference in grain albumin＋globulin content, but glutenin, HMW-GS and LMW-GS content were markedly decreased from Groupâ… to Groupâ…¢. Compared Groupâ… with Groupâ…¡, gluten protein and total protein content had no marked difference, but gli/glu of Groupâ… was lower than that of Groupâ…¡. Gliadin,ω-gliadin andα-gliadin content decreased in the order: Groupâ…¡, Groupâ… , Groupâ…¢, butγ-gliadin decreased in the order: Groupâ… , Groupâ…¡, Groupâ…¢.1.1.3 Nitrogen uptake and distribution characteristics of different groups and its relationship to kernel protein quality At anthesis and maturity, plant nitrogen accumulation amounts of Groupâ… were both markedly higher than these of Groupâ…¡and Groupâ…¢. Nitrogen accumulation amount in grain, nitrogen translocation amount, translocation efficiency and its contribution proportion of Groupâ… were markedly higher than these of Groupâ…¡and Groupâ…¢.Grain protein content was positively correlated to nitrogen accumulation amount at anthesis and nitrogen translocation amount. Glutenin content, dough development time, stability time and sedimentation volume were positively or dramatically positively correlated to nitrogen translocation amount, translocation efficiency and its contribution proportion. N absorption amount after anthesis in kernel was not correlated to upward index value.1.1.4 Changes of protein content in kernel and the relationship to activity of the relevant enzymeAt whole grain filling stage, GS and EP activity in flag leaves were positively or dramatically positively correlated to grain protein content. At 12 days after anthesis, GS and EP activity were positively or dramatically positively correlated to HMW-GS,LMW-GS and glutenin content. At 21 days after anthesis, positively or dramatically positively correlation between GS and EP activity with HMW-GS content were also observed.1.2 Differences. in starch quality of different type wheat cultivars and the relevant physiological basis1.2.1 Classification of different wheat cultivars based on starch qualityBased on amylopectin content, amylose content and total starch content, fifteen cultivars were classified into two groups: low amylopectin content, high amylose content, and low total starch group (Groupâ… ), including Jimai20, Jinanl 7, 9411 etc 13 cultivars, high amylopectin content, low amylose content, and high total starch group (Groupâ…¡), including Ningmai9 and Yangmai9.1.2.2 Difference of grain starch component content of different groups and the relationship to activity of the relevant enzymeFrom anthesis to 21 days after anthesis, amylopectin content of groupâ… was significantly higher than that of groupâ…¡, but from 27 days after anthesis to maturity, the result was reversed. Total starch content has same trend with amylopectin content. At whole grain filling stage, amylose content of groupâ… was significantly higher than that of groupâ…¡. High soluble starch syntheses (SSS) activity enhanced accumulation of amylopectin and amylase in the early stage of filling, but it would accelerate amylopectin accumulated and decelerate amylose accumulated in the middle and late stage of filling. Cultivars with high granule bounded starch syntheses (GBSS) activity had high amylase content.2 Studies on regulating mechanism of quality formation in different type wheat by nitrogen fertilizer rateThe studies, selecting wheat cultivar GC8901 (strong .gluten), Jimai20 (strong gluten), Taishan23 (middle gluten) and Ningmai9 (weak gluten), elucidated the physiological basis of quality formation in different type wheat by nitrogen fertilizer rate. The principal results were as follows.2.1 Effects ofnitrogen fertilizer rate on wheat grain yield and quality in different type wheatFor wheat cultivar GC8901, Jimai20 and Taishan23, treatment with applying 180kg/hm2 obtained high yield. Yield did not significantly increase when nitrogen fertilizer rate increased from 180kg/hm2 to 240kg/hm2, and yield decreased with applying 360kg/hm2 nitrogen fertilizer rate. With regard to wheat cultivar Ningmai9, treatments with applying 240kg/hm2 and 360kg/hm2 obtain high yield, and two treatments had no marked difference.With the increasing of supplied nitrogen amount, grain protein content and protein yield trended to increase-level off-decrease. As to GC8901, Jimai20 and Taishan23, the ranges of nitrogen fertilizer rate for higher protein content and protein yield were 180-240kg/hm2, at the same time with higher sedimentation volume, wet gluten content, dough development time and stability time. When nitrogen fertilizer rate arrived at 360kg/hm2, upward quality index value trended to decrease. With the increasing of supplied nitrogen amount, grain protein content, sedimentation volume, wet gluten content, dough development time and stability time of Ningmai 9 were increased markedly.2.2 Effects of nitrogen fertilizer rate on protein component content in different type wheatFor GC8901, Jimai20 and Taishan23, with the increasing of supplied nitrogen amount, grain gliadin and its component content, albumin+globulin content and total protein content showed to increase at first and then decreased, and treatment with applying nitrogen fertilizer had no marked difference. Glutenin content also showed to increase at first and then decrease, but treatments of N240 and N360 was higher than N180. All protein components content for Ningmai9 increased with the increasing of supplied nitrogen amount, and treatments of N240 and N360 were higher than N180. On the condition of applying nitrogen fertilizer, increasing extent of glutenin and gliadin content were significantly higher than that of albumin+globulin, which is the physiological basis to improve grain protein quality with applying nitrogen fertilizer.For GC8901, Jimai20 and Taishan23, with the increasing of supplied nitrogen amount, HMW-GS content of treatment N240 was markedly higher than that of N180 and N360, and LMW-GS also showed to increase at first and then decrease, which is one of reasons to decrease quality for strong and middle gluten wheat with the excessive applying fertilizer nitrogen amount. HMW-GS and LMW-GS content for cultivar Ningmai9 increased with the increasing of supplied nitrogen amount, and treatments of N240 and N360 were significantly higher than that of N180.2.3 Effects of nitrogen fertilizer rate on nitrogen translocation of different type wheatWith the increasing of supplied nitrogen amount, nitrogen translocation amount and translocation efficiency from vegetative organs to grain showed to increase at first and then decrease, which of treatment N240 was the highest for GC8901, Jimai20 and Taishan23, and N180 for Ningmai9. On the condition of without applying nitrogen fertilizer, translocation efficiency and its contribution proportion of Jimai20 was lower than that of Taishan23, but that of Jimai20 was higher than that of Yaishan23 with applying nitrogen fertilizer, which showed that regulating effect of nitrogen fertilizer to Jimai20 was higher than Taishan23.2.4 Effects of nitrogen fertilizer rate on nitrogen assimilation and protein degradation in flag leaf of different type wheatIncreasing the amount of nitrogen supply from 0 to 240kg/hm2 elevated the activity of GS in flag leaf; when applying nitrogen fertilizer amount arrived at 360kg/hm2, activity of GS reduced, nitrogen uptake amount after anthesis decreased, and the activity of Ep remained low during grain filling, nitrogen remobilization was inhibited. It is one of physiological reasons that protein content of grain would not increase more with excessive nitrogen fertilizer applied.2.5 Effects of nitrogen fertilizer rate on starch synthesis in grain of different type wheatWith the increasing of supplied nitrogen amount, the activities of SSS and GBSS in grain decreased in the early and middle stage of filling, and amylopectin, amylase and total starch content all decreased, which is one of physiological reason that grain weight decreased with the increasing of supplied nitrogen amount. Applying nitrogen fertilizer has no marked effect on ratio of amylopectin and amylase. Compared with different cultivars, grain SSS activities of cultivar GC8901, Jimai20 and Taishan23 were significantly higher than that of Ningmai9 in the early and middle stage of filling, but in the late filling stage, the result was reversed, which is physiological basis that grain amylopectin content of Ningmai9 is significantly higher than these of other cultivars. Grain GBSS activity and amylase content of cultivar Ningmai9 is markedly lower than that of other three cultivars.3 Effects of different phase shading during grain filling stage on quality and yield in different type wheatThe studies, selecting wheat cultivar GC8901 (strong gluten), Jimai20 (strong gluten), Taishan23 (middle gluten) and Ningmai9 (weak gluten), using (15)SN isotope tracing technique, physiological and biochemical analysis method, elucidated the effect mechanism of quality and yield by different phase shading during grain filling stage. The principal results were as follows.3.1 Effects of different phase shading during grain filling stage on grain yield and quality of different type wheatShading at every phase during grain filling stage all decreased grain weight and yield, increased grain protein content, and shading in the middle stage of filling had largest effects on grain yield and protein content, which in the late stage of filling took. second place, and which in the early stage of filling was lest. The increasing of protein content was caused by the decreasing of grain weight.Shading at every phase during grain filling stage all markedly elevated wet gluten content, and treatments with shading at different phase had no significant difference. Shading at every phase during grain filling stage all elevated dough development time, stability time, sedimentation volume, for Jimai20 and Taishan23, which of shading in the middle stage was markedly higher than in the late stage, and late stage was higher than early stage and no shading, but treatment with shading in the early stage with no shading had no marked difference; for Ningmai9, 4 treatments all had significantly difference.3.2 Effects of different phase shading during grain filling on grain protein components content of different type wheatShading at every phase during grain filling all increased grain albumin+globulin, glutenin and gliadin content, but different phases have different regulating effect. Albumin+globulin content decreased in the order: shading at late stage, shading at early stage, shading at middle stage, without shading; glutenin and gliadin content decreased in the order: shading at middle stage, shading at late stage, shading at early stage, without shading. Shading at middle stage obtained the highest glutenin and gliadin content, followed by shading at late stage, which was physiological basis to improve protein quality on the condition of shading at middle and late stage. Shading at middle and late stage significantly increased grain HMW-GS and LMW-GS content for Jimai20 and Taishan23. As to Ningmai9, HMW-GS and LMW-GS content decreased in the order: shading at middle stage, shading at late stage, shading at early stage, without shading, and all treatment had markedly different. Shading at every phase during grain filling stage all increased grain gliadin components content, and increased in the order: without shading, shading at early stage, shading at late stage, shading at middle stage.3.3 Effects of different phase shading during grain filling stage on nitrogen uptake and translocation of cultivar Jimai20Shading at every phase during grain filling stage decreased nitrogen accumulation amount in plant, and decreased in the order: without shading, shading at early stage, shading at middle stage, shading at late stage. The results of 15N isotope tracing experiments showed, that, soil nitrogen amount that wheat plant absorbed was markedly higher than fertilizer nitrogen, and nitrogen translocation amount and its contribution proportion from vegetative organs to grain of soil nitrogen were significantly higher than fertilizer nitrogen also, but the result of translocation efficiency was in reverse order.Nitrogen translocation amount and translocation efficiency from vegetative organs to grain of shading at early stage showed to be highest, and markedly higher that of shading at middle stage and without shading, and that of shading at late stage was the lowest. Nitrogen contribution proportions from vegetative organs to grain of shading at middle and late stage were higher than that of shading at early stage and without shading. Nitrogen absorption amount after anthesis in kemel decreased in the order: without shading, shading at early stage, shading at middle stage, shading at late stage.3.4 Effects of different phase shading during grain filling stage on nitrogen assimilation and protein degradation in flag leaf of different type wheatShading at every phase during grain filling stage all decreased the activities of GS and EP, and decreased free amino acids content and soluble protein content. After dismantling the condition of shading, activities of GS and EP increased and might higher than that of without shading. Compared with different cultivars, when shading at early and middle stage, free amino acids content and activities of GS and EP for Jimai20 and Taishan23 were markedly higher than these of Ningmai9, but the result was in reverse order at late stage.3.5 Effects of different phase shading during grain filling on sucrose synthesis in flag leaf and on starch synthesis in grain of different type wheatShading at every phase during grain filling stage all decreased sucrose content and activity of SPS. After dismantling the condition of shading, sucrose content and activity of SPS renew to a higher level. Compared with different cultivars, sucrose content and SPS activity of Ningmai9 was the highest, Taishan23 took second place, and Jimai20 was the least.Shading at every phase during grain filling stage decreased activities of SSS and GBSS in grain, choked back biosynthesis of amylopectin and amylase. It is one of physiological reason that insufficiency filling and low grain weight. Shading at different phases had different regulating effect on amylopectin and amylase content. Amylopectin and total starch content decreased in the order: without shading, shading at early stage, shading at late stage, shading at middle stage; and amylase content decreased in the order: without shading, shading at late stage, shading at middle stage, shading at early stage. Effect of shading at early stage on activity of GBSS was higher than activity of SSS, which is physiological basis that shading.at early stage would elevate ratio of amylopectin and amylose and improve starch quality.4 Effects of nitrogen fertilizer rate and ratio of base and t0pdressing on nitrogen cycle in plant-soil, yield and qualityThe studies were conducted on high-yield field which returning the crop straw into soil annually, using 15N isotope tracing technique, to elucidate systematically effects of nitrogen fertilizer rate and ratio of base and topdressing fertilizer on nitrogen cycle in plant-soil system, yield, quality and its physiological and ecological basis. The principal results were as follows.4.1 Effects of nitrogen fertilizer rate and ratio of base and topdressing on nitrogen uptake, distribution and translocationMain basal nitrogen absorbed by plant from sowing to jointing stage accounted for 78.04%～89.67%. With increasing topdressing nitrogen proportion appropriately could reduce loss of basal nitrogen, and increased fertilizer-N use efficiency. Fertilizer-N use efficiency of treatment N2 was the highest, its nitrogen fertilizer rate is 168kg/hm2 and ratio of base fertilizer to topdressing is 1:2. With increasing topdressing nitrogen proportion appropriately, the translocation efficiency and the amount of nitrogen assimilation for grain after anthesis and its contribution proportion all increased. The increasing of topdressing nitrogen proportion appropriately promoted nitrogen translocation, and increased protein content and protein yield.4.2 Effects of nitrogen fertilizer rate and ratio of base and topdressing on NO3-N content in 0～200cm soil layersWhen basal nitrogen fertilizer rate was higher than 84kg/hm2 or topdressing nitrogen was higher than 160kg/hm2, more residual soil NO3-N were detected than those in treatment NO in 0～200cm soil layers during wheat growth stage. Soil NO3-N accumulation amount in treatment N2 was less at 100～200cm soil layers, and had no significant difference compared with that of treatment NO at 100～200cm soil layers during wheat growth stage.4.3 Effects of nitrogen fertilizer rate and ratio of base and topdressing on fate of fertilizer nitrogen in plant-soil systemBasal fertilizer-N use efficiency was markedly lower than topdressing fertilizer-N use efficiency, but losses rate of base fertilizer nitrogen was significantly higher than that of topdressing fertilizer nitrogen. Changes of ratio of base and topdressing regulated fertilizer-N distribution proportion at three fates (wheat uptake, soil residual, losses). Higher basal or topdressing fertilizer nitrogen rate both increased fertilizer N residual amount in 0～200cm soil layers, and increased fertilizer N movement depth. Critical value of basal fertilizer moving into 100～200cm soil layers was less than that of topdressing fertilizer. Basal and topdressing fertilizer nitrogen of treatment N2 was not inspected in 100～200cm layers soil in whole growth stage.4.4 Effects of nitrogen fertilizer rate and ratio of base and topdressing on grain yield and qualityApplying N fertilizer significantly increased grain yield, protein content and protein yield, and treatment N2, N5 and N6 were more excellent. With the same fertilizer nitrogen rate, protein content significantly increased with increasing topdressing fertilizer nitrogen rate. Under the condition of this experiment, as far as upward results are concerned, the most appropriate nitrogen fertilizer applying regime recommended is treatment N2, its. nitrogen fertilizer rate is 168 kg/hm2 and ratio of base fertilizer to topdressing is 1:2.
|
PDF Full Text Request