Abstract:

To determine the optimal sowing window for high yield and quality of early indica rice in the Quzhou region, two cultivars—Zhongzu 100 and Zhongzao 39—were used as experimental materials under five sowing date treatments(T1, early spring low-temperature stress; T2, conventional sowing date; T3, optimal light-temperature resource utilization; T4, high-temperature grain-filling period; T5, delayed sowing stress). The effects of sowing date on rice growth stages, physiological traits, yield components, and grain quality were systematically analyzed. The results showed that T3 synchronized key growth stages with the peak availability of light and temperature resources, maintaining the most stable physiological status in plants. Antioxidant enzyme activities (SOD, POD, CAT) remained at relatively low levels, osmotic adjustment substances (soluble sugars, free amino acids) did not accumulate abnormally, and the chlorophyll relative content (SPAD value) was the highest. Yield components were synergistically optimized, with higher numbers of effective panicles, grains per panicle, seed setting rate, and 1000-grain weight, resulting in significantly greater grain yield than the other treatments (p<0.05). Path analysis further revealed that effective panicle number and 1000-grain weight were the primary factors influencing yield, and effective panicle number exerted a significant positive indirect effect on yield via 1000-grain weight. In terms of quality, T3 significantly reduced chalkiness degree and chalky grain percentage, and achieved the highest head rice rate. Based on comprehensive agronomic performance and cultivar characteristics, the suitable sowing period for Zhongzu 100 and Zhongzao 39 in the Quzhou area is early April (T3), with critical boundaries for early and late sowing being late March and late April, respectively. These findings provide theoretical support and practical guidance for precision cultivation and regional cultivar deployment of early indica rice.

Key words: early indica rice, sowing date, yield components, grain quality, physiological traits, path analysis

摘要：

为明确衢州地区早籼稻优质高产的最佳播种时期，以中组100和中早39为供试品种，设置5个播期处理（T1，早春低温胁迫；T2，常规播期；T3，光温资源优化；T4，高温灌浆期；T5，延迟型胁迫），系统分析不同播期对水稻生育进程、生理特性、产量构成及稻米品质的影响。结果表明，T3处理使水稻关键生育期与光温资源高峰期高度同步，植株生理状态最为稳健，抗氧化酶（SOD、POD、CAT）活性维持在较低水平，渗透调节物质（可溶性糖、游离氨基酸）未发生异常积累，叶绿素相对含量（SPAD值）最高；产量构成因子协同优化，有效穗数、每穗粒数、结实率及千粒重均处于较高水平，产量显著高于其他处理（P<0.05）。通径分析进一步揭示，有效穗数与千粒重是影响产量的关键因子，且有效穗数可通过千粒重对产量产生显著正向间接效应。品质方面，T3处理显著降低垩白度和垩白粒率，整精米率居各处理之首。综合品质与产量表现可知，在衢州地区，中组100与中早39的适宜播种期为4月上旬（T3），早播与晚播的临界期分别为3月下旬和4月下旬。本研究结果可为早籼稻的精准栽培与区域化品种布局提供理论依据与实践参考。

关键词: 早籼稻, 播期, 产量构成因子, 稻米品质, 生理特性, 通径分析