【作者】 赵波；

【导师】 孔凡磊； 袁继超；

【作者基本信息】 四川农业大学 ， 作物栽培学与耕作学， 2021， 硕士

【摘要】 玉米机械粒收是未来中国玉米生产发展的必然趋势,对于转变玉米生产方式,引导全国玉米高产高效生产,提高玉米产业竞争力具有重要的意义。籽粒破碎率高是机械粒收技术发展的“瓶颈”性问题,迫切需要开展玉米机械粒收籽粒破碎相关研究来推动我国玉米机械粒收技术应用和发展。本研究于2018年—2020年在四川中江同一地块,采用同一机械、同一操作人员,开展多品种、大跨度多收期试验,同步调查破碎率、各破碎类型占比率、穗粒特性指标,探讨不同收获时期机械粒收籽粒破碎和穗粒特性变化规律,分析籽粒破碎率的影响因素;并于2019年开展玉米果穗不同粒位间机械脱粒破碎率的差异试验。主要研究结果如下:1、随收获时期后移,籽粒破碎率先降低后逐渐升高;不同破碎类型所占比例随收获时期后移会产生变化;参试品种就机械粒收破碎率表现来看,宜机收性仲玉3号最好,其次为先玉1171、正红6号,成单30较差。2、随收获时期后移,玉米籽粒含水率、穗轴含水率降低;籽粒容重和力学强度呈现出逐渐增加的趋势;穗轴硬度呈先逐渐降低后升高再逐渐降低的变化趋势;穗-粒连接力表现出先增加后减小的趋势;籽粒醇溶蛋白含量有降低的趋势,如收获期后移时间较长,籽粒淀粉粒间蛋白质会发生明显降解。3、玉米穗粒特性显著影响机械粒收破碎率,其中破碎率与籽粒含水率和籽粒力学强度符合二次多项式关系;破碎率与穗轴抗折断力呈显著正相关,与籽粒容重呈显著负相关。当籽粒含水率高于20.87%时,随籽粒含水率降低,籽粒力学强度增加,籽粒耐破碎能力提高,是破碎率显著降低的重要原因;当籽粒含水率低于20.87%时,随籽粒含水率降低,籽粒韧性降低、穗轴机械强度增加和籽粒醇溶蛋白含量减少是破碎率升高的重要原因。4、玉米果穗不同粒位籽粒在机械脱粒时,基-中粒的耐破碎能力优于顶粒,造成差异的原因是基-中粒具有显著的粒重和力学强度优势,而粒位间含水率的差异难以解释其耐破碎能力。综上,四川春玉米生产上可利用品种和收期配置原则,选用机械粒收低破碎率表现、籽粒和穗轴力学强度适宜、籽粒醇溶蛋白含量高的品种并结合适当推迟收获时期(生理成熟后10d～20d),利用热量资源达到籽粒在田间的失水干燥,使籽粒力学强度增加,籽粒耐破碎能力提高,来实现低的机械粒收破碎率。本研究结果可为宜机收品种的选育和选择、适宜收期的确定和机械粒收技术的发展提供一定的理论依据。更多还原

【Abstract】 Maize mechanical grain harvest is an inevitable trend of maize production development in China in the future.It is of great significance to change the mode of maize production,guide the high-yield and high-efficiency production of maize and improve the competitiveness of corn industry in china.High grain breakage rate is the"bottleneck"problem in the development of mechanical harvesting technology.It is urgent to carry out relevant research on grain breakage of maize mechanical harvesting to promote the development and application of maize mechanical harvesting technology in China.From2018 to 2020,in the same plot of Zhongjiang,Sichuan Province,using the same machine and the same operator,the experiment of multi variety,large-span and multi harvest dates was carried out,and the broken rate,the proportion of each broken type,and the index of ear grain characteristics were investigated simultaneously,so as to explore the changes of grain broken and ear grain characteristics in different harvest dates,and analyze the influencing factors of grain broken rate.In 2019,the difference test of mechanical threshing broken rate between different maize grain positions was carried out.The main findings are as follows:1.With the backward shift of harvest date,the grain broken rate first decreased and then increased gradually;the proportion of different broken types changed with the backward shift of harvest date.Regarding the performance of mechanical grain harvesting and broken rate of the tested cultivars,Zhongyu 3 was the lowest,followed by Xianyu1171 and Zhenghong 6,and Chengdan 30 was the highest.2.With the backward shift of harvest date,the grain moisture content and cob moisture content decreased;the grain bulk density and mechanical strength increased gradually;the cob hardness decreased first,then increased,and then decreased,after physiological maturity,the cob hardness increased first and then decreased;the ear grain connection capacity increased at first and then decreased;the grain zein content had a tendency to decrease,for example,the grain starch intergranular protein would be degraded obviously when the harvest date moved back for a long time.3.The characteristics of ear and grain significantly affect the mechanical grain harvest broken rate.The relationship between broken rate and grain moisture content and grain mechanical strength was quadratic polynomial.When the grain moisture content is 20.87%,the broken rate is the lowest,which is 1.59%.According to the national standard of broken rate≤5%,the grain moisture content should be controlled between 13.57%and 28.18%.When the facade,side,germ and ventral crushing strength(shear strength)were 231.37N(117.68N),146.24N(126.04N),152.63N(58.85N)and 563.17N(249.14N),respectively,the broken rate was the lowest.The broken rate was positively correlated with the bending strength of 10 cm cob,and negatively correlated with the grain bulk density.When the grain moisture content is higher than 20.87%,the grain mechanical strength increases with the decrease of moisture content,which improves the crushing resistance of grain,which is an important reason for the significant decrease of broken rate.When the grain moisture content is lower than 20.87%,the important reasons for the increase of the broken rate are the decrease of grain toughness,the increase of mechanical strength of cob and the decrease of the content of grain zein.4.In mechanical threshing,the crushing resistance of base-middle grains was better than that of apical grains.The reason for the difference is that the basic-middle grains has significant advantages in grain weight and mechanical strength,while the difference in moisture content between grain positions is difficult to explain its crushing resistance.To sum up,Sichuan spring maize production can use the configuration principle of cultivars and harvest date,select the cultivars with appropriate mechanical strength of grain and cob,high content of zein in grain,and combine with appropriately delaying harvest date,use heat resources to achieve the dehydration and drying of grain in the field,increase the mechanical strength of grain,so as to improve the crushing resistance of grain and achieve low mechanical broken rate.Therefore,this research can provide a certain theoretical basis for the selection and breeding of suitable machine harvested cultivars in actual production,the determination of precise harvesting dates,and the development of mechanical grain harvesting technology.更多还原