The underground reserve (root) has been an uncharted research territory with its untapped genetic variation yet to be exploited. Identifying ideal traits and breeding new rice varieties with efficient root system architecture (RSA) has great potential to increase resource-use efficiency and grain yield, especially under direct-seeded rice, by adapting to aerobic soil conditions. In this review, we tried to mine the available research information on the direct-seeded rice (DSR) root system to highlight the requirements of different root traits such as root architecture, length, number, density, thickness, diameter, and angle that play a pivotal role in determining the uptake of nutrients and moisture at different stages of plant growth. RSA also faces several stresses, due to excess or deficiency of moisture and nutrients, low or high temperature, or saline conditions. To counteract these hindrances, adaptation in response to stress becomes essential. Candidate genes such as early root growth enhancer PSTOL1, surface rooting QTL qSOR1, deep rooting gene DRO1, and numerous transporters for their respective nutrients and stress-responsive factors have been identified and validated under different circumstances. Identifying the desired QTLs and transporters underlying these traits and then designing an ideal root architecture can help in developing a suitable DSR cultivar and aid in further advancement in this direction.

Dry direct seeded rice (DSR) has emerged as an economically viable alternative to puddled transplanted rice to address emerging constraints of labor and water scarcity and the rising cost of cultivation. However, wide adoption of DSR is seriously constrained by weed management trade-off. Therefore, the availability of effective weed control options is critical for the success and wide-scale adoption of DSR. A field study was conducted at ICAR-National Rice Research Institute, Cuttack, India, in the dry seasons of 2015 and 2016 to evaluate the performance of three crop establishment methods and five weed control practices on weed management, productivity, profitability and energetics of dry DSR. The results demonstrated that weed density and weed dry weight was lower in drill seeding than broadcast seeding by 26–36% and manual line-seeding by 16–24%, respectively, at 30 and 60 days after crop emergence (DAE). Among herbicides, post-emergence application (17 DAE) of azimsulfuron was most effective in controlling weeds compared to early post application of bispyribac-sodium and bensulfuron-methyl+pretilachlor. Weed competition in the weedy check treatment resulted 58% reduction in rice yield. Among establishment methods, drill-seeding was most profitable with US $ 685 ha⁻¹ higher net income than broadcast seeding primarily due to higher yield. Among weed control treatments, azimsulfuron was most profitable resulting in US $ 160 and 736 ha⁻¹ higher net income than weed free and weedy check, respectively. The specific energy was lowest for drill seeding among establishment method and azimsulfuron among weed control practices, suggesting lowest energy consumed in producing per unit of grain yield.

Weed infestation is the major yield limiting factor in direct wet-seeded rice (WSR). Herbicides use is gaining acceptance among the farmers as it is easy, economical, time saving, and efficient to manage weeds. The herbicide mixtures with different modes of action are preferable to use in rotation. An experiment was conducted to evaluate and identify a suitable pre-mix herbicide mixture and its dosage rate to get optimum weed management and rice yield in WSR during wet seasons of 2017 and 2018 at research farm of ICAR-National Rice Research Institute, Cuttack, Odisha, India using randomized complete block design with three replications. Nine treatments were tested including: viz. post-emergence application (PoE) of florpyrauxifen-benzyl + cyhalofop-butyl at 120, 150, 180 and 360 g/ha; florpyrauxifen-benzyl at 25 and 30 g/ha PoE; bispyribac-sodium 30 g/ha PoE; weed free and weedy check. Among the herbicide treatments, florpyrauxifen-benzyl + cyhalofop-butyl 150 g/ha PoE was most effective to control weeds with the lowest weed density, biomass, and weed index, lower weed persistence index and highest weed control index, weed control efficiency, crop resistance index, treatment efficiency index and weed management index at 60 days after sowing in WSR with higher rice grain yield, and was at par with the weed free. In weedy check, 40% rice yield loss was recorded. Thus, florpyrauxifen-benzyl + cyhalofopbutyl 150 g/ha PoE may be recommended for effective weed control in direct wet-seeded rice.