播种深度对夏玉米幼苗性状和根系特性的影响

Effects of sowing depth on seedling traits and root characteristics of summer maize

选用郑单958(ZD958)和先玉335(XY335)为试验材料,在砂培和大田条件下设置3、5、7和9 cm 4个播种深度,并在大田条件下以不同播种深度混播作为对照(CK),研究播种深度对夏玉米幼苗性状和根系特性的影响.结果表明:随着播种深度的增加,夏玉米的出苗率下降,出苗时间延长.ZD958和XY335播深9 cm的出苗率较3 cm的分别降低9.4%和11.8%,出苗时间较3 cm的均延长1.5 d.随着播种深度的增加,幼苗长度及幼苗整齐度显著降低,中胚轴长度显著增加,胚芽鞘长度差异不显著;初生胚根长度逐渐减小,次生胚根总长度逐渐增加,总根长度差异不显著;幼苗与中胚轴的总干质量增加,总根干质量差异不显著.随播种深度的增加,种子萌发时幼苗各部位可溶性糖含量增加,营养物质消耗量增加,幼苗根系生长速度增加,根系活力降低,总节根数及节根层数增加.播深增加后出苗率及幼苗活力的降低导致收获穗数的显著降低,最终影响产量形成.此外,播深一致有利于群体整齐度的提高和群体性状的改善,从而提高产量.

Two summer maize hybrids,Zhengdan 958（ ZD958） and Xianyu 335（ XY335）,were used as experimental materials. 4 sowing depths（ 3,5,7 and 9 cm） and uneven sowing depth（ CK） were designed under sand culture and field experiments to investigate the effects of sowing depth on seedling traits and root characteristics of summer maize. The results showed that the seedling emergence rate gradually decreased and seedling emergence time gradually lengthened as the sowing depth increased. Compared with the sowing depth of 3 cm,the seedling emergence rates of ZD958 and XY335 sown at the depth of 9 cm were reduced by 9. 4% and 11. 8%,respectively,and the seedling emergence duration was prolonged 1. 5 d. With the increasing sowing depth,the seedling length and uniformity decreased significantly,the mesocotyl length increased significantly,while the coleoptile length had no significant difference; the primary radicle length gradually decreased,the total length of secondary radicle gradually increased,and the total root length had no significant difference; the total dry mass of seedling and mesocotyl increased significantly,and the total root dry mass had no significant difference. With the increasing sowing depth,the soluble sugar content in each part of seedling increased and the amount of nutritional consumption of germinating seeds increased,the seedling root growth rate increased,but the root activity decreased,and the number of total nodal root and nodal layers increased. With the increasing sowing depth,harvested ears per unit area were reduced by decreased seedling emergence rate and seedling vigor,thus influenced the yield. In addition,uniform sowing depth could improve the canopy uniformity and relative characteristics,then increase the yield.