Effects of alternate wetting and drying irrigation management and air temperature during grainfill on rice grain physicochemical and functionality traits of US inbred varieties

Authors: Chen, Ming Hsuan; McClung, Anna; Rohila, Jai; Barnaby, Jinyoung

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2021
Publication Date: 4/21/2021
Citation: Chen, M., McClung, A.M., Rohila, J.S., Barnaby, J.Y. 2021. Effects of alternate wetting and drying irrigation management and air temperature during grainfill on rice grain physicochemical and functionality traits of US inbred varieties. Cereal Chemistry. https://doi.org/10.1002/cche.10440.
DOI: https://doi.org/10.1002/cche.10440

Interpretive Summary: Depletion of irrigation resources represents a threat to US rice production. To conserve water, US rice producers are adopting alternate wetting and drying water management (AWD) which allows the soil to dry to a predetermined level before re-irrigating the field. Thus far, careful management of AWD practices have been shown to be effective in saving water while maintaining grain yield, but information is lacking on how AWD impacts grain quality. We conducted two AWD studies using seven rice varieties that are diverse in cooking properties based on grain amylose content and gelatinization temperature. Treatments that differed in the degree of soil moisture and the timing of draining the fields were used to compare to a continuously flooded control. Results demonstrated that the AWD treatments did not affect head rice yield, grain chalkiness, grain size, or grain cooking traits. This research demonstrated that AWD cultural management practices that save irrigation water do not negatively impact grain quality traits that are important to determining crop value.

Technical Abstract: Declining underground water resources and warming cropping seasons present challenges to rice production. The alternate wetting and drying (AWD) water management system conserves water, but its impact on rice grain quality is not well understood. To determine the effects of AWD irrigation management and varying seasonal temperatures on rice grain quality, a field experiment with three AWD irrigation methods and continuous flood (CF), as a control, was conducted. Two environmental temperatures were imposed by two one month apart planting dates. Results revealed that the AWD and CF at either planting date had no significant effect on 100-kernel wt, grain shape traits or grain chalk, total milling and head rice yields, and gelatinization temperature nor the contents of apparent amylose, protein, and total carbon of milled rice. However, high air temperatures during the grainfill period of the first planting resulted in lower head rice yield and higher chalkiness in brown rice. It also affected rice grain functional properties– lower protein and total carbon contents, lower apparent amylose content in low amylose varieties, and higher gelatinization temperature in a high gelatinization-temperature variety. In conclusion, AWD had no significant impact on rice grain quality, however, the elevated temperatures during grain development significantly affected important grain quality traits. This study demonstrated that rice varieties can withstand mild or severe AWD treatments with no negative effects on grain appearance traits and functional properties.