| Fresh maize has the advantages of rich nutrition,unique flavor and palatability.Fresh maize plays an important role in improving the structure of planting industry,advancing the process of agricultural industrialization,increasing agricultural efficiency and farmers’ income.In recent years,with the development of social economy,fresh maize has become more and more popular among consumers,and become a new bright spot in the development of green agriculture.Jiangsu province is the main producer of fresh maize in China,in which the fresh waxy maize accounts for 90% of the total fresh maize planting area.As a kind of economic crop with higher added value,the quality and yield of fresh maize is particularly important.Therefore,it is significant to understand grain-filling characteristics,the dynamic changes of nutrients and Nutrient-related synthases during grain growth and development,which could be beneficial to ensuring the quality and yield of fresh waxy mazie.In this experiment,six fresh waxy maize varieties(Suyunuo 5,Sukenuo 11,Sukenuo 12,Sukenuo 1501,Sukenhuanuo 2008 and Wannuo 2000)are selected as test material.Through in the field experiment,the yield,filling characteristics,dynamic changes of nutrient components and the differences in related synthetase activities among variety are studied.The main results are as follows:1.Yield components and grain filling characteristics of fresh waxy maizeBy analyzing the nutritional components of 6 varieties of waxy maize,the results showed that the yield components and filling characteristics were significantly different among the varieties.Through the correlation and path analysis of fresh ear yield and yield components,the results showed that the direct path coefficients of 100-grain fresh weight and number of grains per ear are higher than other factors.In addition,the indirect path coefficients produced by ear diameter and ear length are positive,while the direct path coefficients of bald tip and indirect path coefficients are negative.The maximum and average grain-filling rates are positively correlated with the yield of fresh panicle.According to the change of grain relative water content,the suitable harvest time of Suyunuo 5,Sukenuo 11,Sukenuo 12,Sukenuo 1501 and Sukehunuo 2008 is 20-22 days after pollination,and the suitable harvest time of Wannuo 2000 is 22-26 days after pollination.Therefore,grain number per ear,fresh weight per hundred grains,average grain filling rate and maximum grain filling rate are the important characteristics of high-yield fresh waxy maize.Wannuo 2000 has a longer suitable harvest period and has the characteristics of harvesting resistance.In this experiment,the yield components and filling characteristics of fresh waxy maize were analyzed.The results showed that the waxy maize varieties with higher grain number per ear,fresh weight value per hundred grains,maximum grain filling rate and average grain filling rate have higher fresh ear yield.2.Nutritional quality of fresh waxy maizeBy analyzing the nutritional components of 6 varieties of waxy maize,the results showed that with the grain filling,the contents of sucrose,soluble sugar and crude protein in the grains of fresh waxy maize decreased gradually.The content of crude starch,amylopectin and the ratio of amylopectin to crude starch showed an upward trend,and the content of crude fat first decreased and then increased.The changing trend of crude starch content is closely related to the accumulation of grain dry matter.Before pollination 22 d,crude starch content showed a rapid upward trend,and stabilized after 22 d,which coincided with the time of maximum filling rate.The moisture content of fresh waxy maize combined with the ratio of amylopectin to crude starch can be used as an index to confirm the suitable harvest time of fresh waxy maize.The change rules of nutrient composition during grain filling of waxy corn are studied in this experiment,and it is suggested that water content combined with the ratio of amylopectin to crude starch could be used as an index to confirm the suitable harvest time of fresh waxy maize.3.Enzymes related to nutrient composition synthesis of fresh waxy maizeThe enzymes related to nutrient composition synthesis of six varieties of waxy maize were analyzed.The results showed that the activities of AGP enzyme and SSS enzyme on24 day after pollination are lower than those on 15 days after pollination.The activity of GBSS on the 15 th day after pollination is lower than that on the 24 day after pollination,which is consistent with the rapid accumulation of amylopectin on 15 days after pollination and the rise of amylose on 15 days after pollination.The activities of NR and GS in grains at 24 d after pollination are lower than those on 15 d after pollination.The activities of NR and GS are not significantly different on 24 d after pollination,which was consistent with the fact that protein content is high at 15 d after pollination and the differences among varieties were small at 24 d after pollination.Through the study on the activities of enzymes related to the synthesis of nutrients,it is clear that the level of nutrients at 15 d and 24 d after pollination is closely related to the strength of related synthase activities. |
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