The dry matter partitioning coefficient (PC) reflects the distribution and accumulation of dry matter in crop organs. Understanding the responses of PC to drought stress is fundamental for understanding crop development under drought stress. Using field data collected under drought stress conditions during the period 2013-2015 at three sites (Xiajin, Shandong; Gucheng, Hebei; and Yuncheng, Shanxi) in North China, we quantified the effects of different drought stress intensities on the PC of stems, leaves and ears during the development stages (from emergence to jointing, from jointing to tasseling, and from tasseling to maturity). The results showed that PC of stems, leaves and ears showed significant quadratic relationships with relative soil moisture during all stages. Leaf PC was increased by 0.04-0.09 during the grain-filling stage under light and moderate drought stress, and was increased by 0.17 during the tasseling stage under sever drought stress. On the contrary, drought stress had negative effects on the ear PC. With the increases of drought stress, less dry matter was allocated to ears. Under light to severe drought stresses, ear PC was decreased by 0.08-0.34. However, no consis-tent pattern was observed for the effects of drought stress on stem PC: negative effects were observed during the vegetative growth stage and positive effects were found in the mature stage. Overall, the degree of the responses of crop PC to drought stress under different phenology stages was in the order of grain-filling stage (positive) > tasseling stage (negative) > seedling stage (negative).
干物质分配系数反映作物各器官干物质的分配与积累,研究干物质分配系数对干旱胁迫的响应,是研究干旱胁迫对作物生长发育影响的基础.本文基于华北夏玉米主产省山东、河北和山西3个试验点2013—2015年田间水分控制试验资料,建立了夏玉米苗期、抽雄期、灌浆期3个主要发育阶段叶、茎、穗的干物质分配系数与土壤相对湿度的定量关系模型,分析了叶、茎、穗干物质分配系数对不同程度干旱胁迫的响应.结果表明: 3个阶段叶、茎、穗的干物质分配系数与土壤相对湿度均呈显著的一元二次关系.干旱胁迫下,叶片向外转运的干物质相对减少,叶干物质分配比例增加,并且在轻、中度干旱胁迫时的灌浆期(叶干物质分配系数增加0.04~0.09)以及重度干旱胁迫时的抽雄期(叶干物质分配系数增加0.17)响应最敏感.穗干物质分配系数对干旱胁迫表现为负响应,干旱胁迫越严重,分配系数越小,轻-重度干旱胁迫使穗干物质分配系数减小0.08~0.34.茎干物质分配系数对干旱胁迫的响应总体表现为灌浆期(正响应)＞抽雄期(负响应)＞苗期(负响应).
Keywords: North China.; drought stress; dry matter partitioning coefficient; summer maize.