Effects of root hair length on potassium acquisition in rice (Oryza sativa L.)

Potassium (K) deficiency limits rice production worldwide. It has been shown that variation in root traits, such as root hair length, influences ion uptake in many plant species. In this study, we explored natural variation of root hair length of twelve rice varieties in a roll-up system. We found a large phenotypic variation for root hair traits ranging from 0.14 to 0.21 mm. Niaw San-pah-tawng and most upland varieties had long root hairs while lowland varieties had short root hairs. Six lowland varieties contrasting in root hair length were planted in pots under high and low K concentrations. K stress was found to decrease average biomass by 60.93% and K tissue content by 66%. Root to shoot ratio was not affected by K stress. Correlation analysis indicated that long root hair was associated with reduced percentage of leaf senescence, enhanced plant biomass, and improved tissue K content under low K condition. Our results suggest that long root hair could be a useful trait for plant breeding to improve K acquisition in rice.