Dense planting is one of the main measures to improve the high yield cultivation of maize, and density has a significant effect on the formation of maize starch. Therefore, this study analyzed the granule size distribution and viscosity parameters of different types of spring maize kernels under different increasing density conditions for improving the quality of maize starch.

The field experiments were conducted at the Gongzhuling experimental base in Jilin province in 2019 and 2020. In the present experiments, eight main maize varieties in Northeast China, such as Xianyu 335, Zhengdan 958 and Nonghua 101, etc, were selected as experimental materials, and two planting densities of 67 500 and 97 500 plants/hm² were set. The granule size distribution and viscosity parameters of starch in different treatments were measured by diffraction particle size analyzer and viscosity analyzer, and the relative quality of maize was measured by near-infrared analyzer, and the correlation analysis was conducted to clarify the effects of increasing density on the granule size distribution and viscosity parameters of endosperm starch in spring maize.

The results showed that with the increase of planting density, maize grain yield and starch content increased significantly, and the increase of density significantly increased the volume, surface area and number percentage of large (>17 μm) starch granules, while the opposite trend was observed in the volume, surface area and number percentage of small (<3 μm) starch granules. It could be seen that with the increase of planting density, the volume and number percentage of small starch granules in maize kernels decreased significantly, and the volume and number percentage of large starch granules increased, indicating that increasing density was beneficial to the increase of the volume ratio of large starch granules, that is, increasing density promoted the accumulation of starch and increased the number of large starch granules and the formation of individual volume. At the same time, it was found that the peak viscosity, trough viscosity, breakdown and final viscosity of maize starch were significantly increased after increasing density. The results of correlation analysis showed that the starch content, yield and viscosity parameters of maize grain were negatively correlated with the volume percentage of small starch granules, significantly or extremely significantly negatively correlated with the volume percentage of medium (3-17 μm) starch granules, and significantly or extremely significantly positively correlated with large (>17 μm) starch granules.

Increasing planting density could increase maize grain yield, starch content and its viscosity parameters by mainly affecting the granule size distribution of endosperm starch, namely increasing the proportion of large starch granules and reducing the proportion of small and medium-sized ones.