Effect Of Sowing Date On Growth,Development,Yield And Nutritional Quality Of Fresh Maize In Guiyang Region

This experiment was conducted at the National Agricultural Meteorological Testing Station in Guizhou Province from 2021 to 2022.A two-factor split plot design was used,with three varieties of fresh maize,Wan Nu 2000（A1）,Nongke Nu 336（A2）,and Cai Tian Nu 6（A3）,Set 6 sowing dates（month/day）:B1（3/10）,B2（3/20）,B3（3/30）,B4（4/9）,B5（4/19）,B6（4/29）.The study aimed to explore the effect of sowing period on the growth and development,yield,and quality of fresh maize,and to provide reference for timely sowing and high-yielding and high-quality cultivation of fresh maize in the region.The differences in the growth and development characteristics of fresh maize,the accumulation of dry matter and nitrogen,phosphorus,and potassium,the differences in photosynthetic characteristics and changes in starch synthesis-related enzyme activities,the differences in grain filling characteristics and their relationship with meteorological factors,the formation process of yield and post-flowering nutritional quality,and their relationship with meteorological factors were studied.The main research results are as follows:1.Under the experimental conditions,with the delay of sowing date,the whole growth period of fresh corn was shortened,the spinning-harvesting period was relatively stable,and the seedling-spitting stage was shortened,among which the shortening of the jointing-large trumpet mouth period was the most obvious,and the whole growth period（84.33d and 92.33d）of the two-year B6 sowing period was 25.34d and 20.34d shorter than that of B1（109.67d and 112.67d）,respectively.The duration of seeding-spitting and spinning-harvesting was linearly negatively correlated with the average daily average and effective accumulated temperature.With the postponement of the sowing period,the leaf area index,panicle position coefficient and stem thickness at the jointing stage showed a trend of increasing first and then decreasing at the jointing stage.2.Planting date significantly affected the accumulation of dry matter at different growth stages and the distribution of dry matter in various organs of fresh maize.With the delay of planting date,the accumulation of dry matter during the jointing,tasseling,silk,and harvest stages showed varying degrees of increase.During the jointing-tasseling period,leaf growth was the main contributor to dry matter accumulation,while stem growth was the main contributor during the tasseling-silking period.Stem dry weight distribution during the jointing-tasseling period showed an increasing trend with the delay of planting date.During the silk-harvest period,grain growth was the main contributor to dry matter accumulation,and grain dry weight accounted for the highest proportion in both years in B6（36.21%）and B4（32.05%）,respectively.Nitrogen and phosphorus accumulation were highest in grain during the harvest period,while potassium accumulation was highest in stems.The accumulation of nitrogen,phosphorus,and potassium in the plant and its various organs showed an increasing trend first and then a decreasing trend with the delay of planting date.3.As the planting date is delayed,the weight of fresh maize seeds,the active filling period,and the filling duration exhibit a trend of initial increase and subsequent decrease,with the B4 planting date(17.32 g·100 seeds^-1,21.84 d,and 34.94 d)achieving the maximum values.The accumulation of grain dry matter is highly positively correlated（P<0.01）with the maximum filling rate,the average filling rate,and the filling rate grain weight,and is positively correlated（P<0.05）with the active filling period and the filling duration.The average filling rate,the filling rate grain weight,and the accumulation of grain dry matter are significantly affected by various meteorological factors during the filling period,with the daily average temperature having the greatest impact followed by sunshine hours,effective accumulated temperature,and rainfall,all of which increase with an increase in the daily average temperature,sunshine hours,and effective accumulated temperature during the grain filling period,and exhibit a positive correlation when the rainfall during the filling period is less than 160 mm,and a negative correlation when it exceeds 160 mm.4.The net photosynthetic rate,stomatal conductance,intercellular CO2concentration,transpiration rate,and chlorophyll fluorescence parameters of different fresh maize varieties showed significant differences under different planting dates,and exhibited varying degrees of increase with delayed planting dates.The activities of starch synthesis-related enzymes,AGPase,DBE,SS,and SBE,varied significantly among years,planting dates,and varieties.The maximum enzymatic activity of each variety occurred during the B3 to B5 planting period.ADPG,SS,SBE,and DBE were all significantly positively correlated with filling rate（P<0.01）,while ADPG,SS,SBE,and DBE were significantly（P<0.01）or significantly（P<0.05）positively correlated with the accumulation of amylopectin in branched and linear chains.5.There are significant differences in fresh maize yield between different planting periods,and there is a significant nonlinear regression correlation between planting period and yield（y=18036.79-192.74x+14.75x²-0.19x³）.The yield shows an increasing trend at first and then a decreasing trend as the planting period is delayed.The yield is highly positively correlated with rainfall,sunshine hours,and effective accumulated temperature.The gray correlation ranking of meteorological factors affecting yield is as follows:effective accumulated temperature（0.810）,average daily temperature（0.792）,rainfall（0.682）,and sunshine hours（0.626）.6.As the time after silking increases,the fresh maize grain crude fat and amylose content show an increasing trend,while crude protein and lysine content show a decreasing trend.The soluble sugar and folate content exhibit an increasing trend followed by a decreasing trend.The formation of fresh maize nutritional quality is significantly affected by the sowing period.With the delay of the sowing period during the harvest period,the grain crude fat,crude protein,amylose,lysine,soluble sugar,and folate content all exhibit varying degrees of increasing trend.Meteorological factors have varying degrees of significant or highly significant positive correlations with nutritional quality.Effective accumulated temperature and mean temperature are the main meteorological factors affecting crude protein,crude fat,and folate content.The sunshine hours and effective accumulated temperature are the main meteorological factors affecting amylose content.The sunshine hours and rainfall are the main meteorological factors affecting amylopectin and lysine content.Sunshine hours exhibit a highly significant or significant negative linear correlation with crude protein and crude fat content,and a significant nonlinear correlation with lysine content that decreases first and then increases,and with amylopectin and folate content that increases first and then decreases.Effective accumulated temperature exhibits a significant positive linear correlation with crude protein and amylose content,and a significant nonlinear correlation with crude fat and amylopectin content that increases first and then decreases,and with lysine content that decreases first and then increases.In summary,the sowing date significantly affected the growth,yield and quality of fresh maize in Guiyang.The output of agricultural glutinous 336 and Caitian glutinous No.6 was the highest with B5(22281.95kg·hm^-2 and 21155.52 kg·hm^-2),and the highest in Wannuo 2000 with B4～B6.The nutritional quality index of each variety at the harvest stage was the highest value of B2～B6.Sowing at the right time increased the leaf area index,plant height and panicle height of the fresh maize population,promoted the accumulation and distribution of dry matter before and after spinning and the accumulation of nitrogen,phosphorus and potassium during the harvest period,the active growth period of grain filling and the end stage of filling became longer,the filling period was shortened,the duration of the rapid growth period and the slow increase period became longer,the sunshine hours,the average daily temperature and effective accumulated temperature increased,and the rainfall was moderate,which improved the photosynthetic properties of leaves and the enzyme activities related to grain starch synthesis,which was more conducive to the filling and accumulation of various nutrients to the grain.Wannuo 2000 in Guiyang area was sown on April 26～30,and agricultural glutinous 336 and Caitian glutinous No.6 were sown on April 17～23,which was conducive to their growth and development to obtain higher yield and quality.