Heterosis Of Endosperm Cell Number And Size In Maize Grains

Maize grain weight is one of the factors of yield,and its weight affects the yield.Endosperm accounts for more than 80%of maize grain weight,and its characteristics are closely related to grain weight.Heterosis exists in maize grain weight.The study on the effect of endosperm cell number and size on grain weight heterosis has important guiding significance for the improvement of maize germplasm resources and breeding of high-yield varieties.In this study,8 main hybrids and their parents and 25 key inbred lines were used as test materials in the spring and summer of 2022 to measure the number of endosperm cells and single-cell sectional area,analyze the heterosis of the number and size of endosperm cells in hybrid grains,and the effect of the accumulation of grain material and the proliferation characteristics of endosperm cells on the grain weight of hybrid was determined.It provides provide the basis for maize inbred line breeding and hybrid selection.The results showed that:（1）Correlation analysis of endosperm cell number and area with grain traits:The endosperm cell number of single grain was positively correlated with grain fresh weight and grain volume,and was positively correlated with grain dry weight and grain width.The section area of single endosperm cells was negatively correlated with dry weight and volume.（2）Correlation analysis of endosperm cell number and area with grain-filling capacity:The number of endosperm cells was positively correlated with the number of days and grain-filling rate at the maximum grain-filling rate,and the growth amount and grain-filling duration of the maximum grain-filling rate were significantly positively correlated.Endosperm cell area was significantly negatively correlated with days at maximum grain-filling rate and very negatively correlated with growth at maximum grain-filling rate.（3）The Over high parent heterosis of endosperm cell number was the main reason for the heterosis of grain weight:There was no significant difference in the number of endosperm cells between two sowing periods,but there was significant difference in the number of endosperm cells between different parts of the same ear.The number of endosperm cells in inbred lines ranged from 369,800 to707,400 per grain,and the average number of endosperm cells was 509,900 per grain.The number of endosperm cells in hybrids ranged from 615,300 to 844,100 per grain,with an average of 724,700 per grain.There was a significant positive correlation between the number of endosperm cells and the number of fresh weights.The number of endosperm cells of each hybrid was significantly greater than that of the parent inbred line,which was an important reason for the generation of grain weight heterosis.Therefore,at least one parent with a large number of endosperm cells should be selected in the maize breeding hybrid.（4）The heterosis of endosperm cell area was not consistent among different varieties:The single endosperm cell area of maize inbred lines ranged from 9100 to 21,200μm² per cell,with an average of 13,500μm² per cell.The single endosperm cell area of hybrid seed（F₂）ranged from 9500 to 15400μm² per cell,with an average of 12,700μm² per cell.The heterosis of endosperm cell area was not consistent among different varieties.