Abstract Reducing water inputs, by maintaining grain yield quality, is important for sustainable production of rice. This study was conducted to investigate the influence of different water management techniques on milling recovery, grain quality, and mercury uptake in rice under dry direct-seeded and transplanted production systems. Two aromatic rice cultivars (Basmati-515 and Chenab Basmati) were planted in conventional puddled-transplanted rice (TPR) and dry direct-seeded rice (DDSR). Three irrigation management systems, based on soil moisture tension (SMT), continuous flooding (> −10 kPa SMT), alternate wetting and drying (AWD) (−20 kPa SMT) and aerobic rice (−40 kPa SMT) were maintained. Rice planting in DDSR system performed comparable to TPR, however, percentage of broken rice, chalky kernels, abortive kernels and opaque kernels were higher (5–8 %, 20 %, 19 % and 25 %, respectively) under DDSR system. However, kernel amylopectin contents and mercury uptake were reduced by 9% and 11 % under DDSR system. In AWD irrigation management, substantial increase in brown head rice (11 %), white head rice (15 %) and kernel protein contents (11 %) were recorded as compared to aerobic irrigation management. However, AWD irrigation reduced the kernel chalkiness (42 %), abortive kernels (51 %) and opaque kernels (62 %) as compared to aerobic irrigation management. Moreover, the AWD irrigation threshold also reduced the kernel amylose contents (15 %), amylopectin contents (6%) and mercury uptake (21 %) in comparison to continuous flooded irrigation threshold. In conclusion, AWD improved the milling recovery as well as grain quality and reduced the mercury uptake under TPR and DDSR in both rice cultivars. Rice cultivation under DDSR in combination with AWD can help to improve the quality traits while reducing the total water inputs and heavy metal accumulation.

中文翻译：

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水分管理技术对不同水稻生产系统中碾磨回收率、谷物质量和汞吸收的影响

摘要 通过保持粮食产量质量来减少水的投入，对于水稻的可持续生产具有重要意义。本研究旨在调查不同水分管理技术对旱作直播和移栽生产系统下水稻的碾磨回收率、谷物质量和汞吸收的影响。两种芳香水稻品种（Basmati-515 和 Chenab Basmati）被种植在常规水坑移栽水稻 (TPR) 和旱直播水稻 (DDSR) 中。维持了基于土壤水分张力 (SMT)、连续洪水 (> -10 kPa SMT)、交替干湿 (AWD) (-20 kPa SMT) 和好氧水稻 (-40 kPa SMT) 的三种灌溉管理系统。DDSR 系统中的水稻种植表现与 TPR 相当，但是，碎米、白垩粒、在 DDSR 系统下，流产籽粒和不透明籽粒更高（分别为 5-8%、20%、19% 和 25%）。然而，在 DDSR 系统下，籽粒支链淀粉含量和汞吸收量分别降低了 9% 和 11%。在 AWD 灌溉管理中，与有氧灌溉管理相比，糙米 (11%)、白精米 (15%) 和籽粒蛋白质含量 (11%) 显着增加。然而，与有氧灌溉管理相比，AWD 灌溉降低了谷粒的垩白度 (42%)、败育谷粒 (51%) 和不透明谷粒 (62%)。此外，与连续淹没灌溉阈值相比，AWD 灌溉阈值还降低了籽粒直链淀粉含量 (15%)、支链淀粉含量 (6%) 和汞吸收 (21%)。综上所述，在 TPR 和 DDSR 下，AWD 提高了两种水稻品种的碾磨回收率和谷物质量，并降低了汞的吸收。DDSR与AWD相结合的水稻栽培有助于改善品质性状，同时减少总水分输入和重金属积累。