Chilling is a major constraint on rice production in mountainous regions of the tropics and in the temperate rice-growing zones of the world. In this study, our goal is to quantify the impacts of chilling at the tillering phases on rice growth and grain yield. In 2017 and 2018, we conducted a factorial chilling treatment at four temperatures (T1, T2, T3 and T4) and four duration days (D2, D4, D6 and D8) on rice plants at the early, middle and late tillering phases. The results showed that chilling at the tillering phases delayed rice growth period. The rice grain yield slightly increased with decrease in chilling temperature but significantly decreased with increase in chilling duration at the tillering phases. For the chilling treatment at T1 (lowest temperature), the D2 (shortest duration) had positive effects on rice yield, while the D8 (longest duration) had adverse effects on rice yield. The middle and late tillering phases were the critical growth phases for rice spike numbers formation, with the increase in temperature and duration, the rice spike numbers per plant significantly decreased. The decrease in chilling temperature and increase in chilling duration both decreased rice thousand-grain weight under chilling treatments at tillering phases. The prolongation of days from emergence to flowering led to increase in rice aboveground biomass per plant and allocation index of stem; however, the decrease in days from flowering to maturity led to reduction in allocation index of panicle and grain yield under chilling treatments at tillering phases. This study could help farmers to better understand the impacts of chilling on rice growth and yield, especially for rice that are prone to chilling.

中文翻译：

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分蘖期低温对东北水稻生长和产量的影响

寒冷是热带山区和世界温带水稻种植区水稻生产的主要制约因素。在这项研究中，我们的目标是量化分蘖期低温对水稻生长和谷物产量的影响。在 2017 年和 2018 年，我们在分蘖早、中、晚三个阶段对水稻植株进行了四个温度（T1、T2、T3 和 T4）和四个持续天数（D2、D4、D6 和 D8）的因子低温处理。结果表明，分蘖期低温延缓了水稻生长期。分蘖期水稻籽粒产量随冷藏温度的降低略有增加，但随着冷藏时间的增加显着降低。对于T1（最低温度）的低温处理，D2（最短持续时间）对水稻产量有积极影响，而D8（最长持续时间）对水稻产量有不利影响。分蘖中后期是水稻穗数形成的关键生长期，随着温度和持续时间的增加，水稻单株穗数显着减少。分蘖期低温低温处理和低温持续时间延长均降低了水稻千粒重。从出苗到开花的天数延长导致水稻单株地上生物量和茎分配指数增加；然而，从开花到成熟的天数减少导致分蘖期低温处理下的穗分配指数和籽粒产量降低。这项研究可以帮助农民更好地了解低温对水稻生长和产量的影响，