Responses of candidate green super rice and super hybrid rice varieties to simplified and reduced input practice

Abstract Producing higher grain yield with less environmental impact is a challenge for the future of agriculture. Breeding green super rice (GSR) varieties is one of the promising ways to meet this challenge. Green super rice is supposed to have better performance than super hybrid rice (SHR) under reduced input condition. In the present study, seven elite candidate GSR varieties and five representative SHR varieties were planted under the farmers’ practice (FP) and the simplified and reduced input practice (SRIP) in 2015 and 2016. The objectives were to compare the grain yield and NUE of the candidate GSR and SHR under FP and SRIP, and investigate the agronomic and physiological traits of GSR. Averaged across all varieties, the reduction in grain yield at SRIP compared to FP was 1.04 t ha −1 in 2015 (10.37%) and 0.50 t ha −1 in 2016 (5.55%). The average grain yield of GSR varieties was similar to that of SHR in 2015, but SHR had significantly greater (7.42%) average grain yield than GSR in 2016. In comparison to FP, yield reduction at SRIP for the candidate GSR and SHR varieties was 9.27% and 11.48% respectively in 2015, and 4.74% and 5.85% respectively in 2016. Grain yield of FP was significantly correlated with that of SRIP (R 2  = 0.73). Averaged across varieties, total aboveground nitrogen uptake and nitrogen use efficiency for grain production between GSR and SHR were comparable. Among the GSR varieties, 9Y6H exhibited relative high yield stability and NUEg across treatments and planting years; however, SHR varieties showed consistently better yield stability than most of the GSR varieties. Overall, candidate GSR varieties had similar response to SRIP with the SHR varieties. In addition to breeding GSR varieties, future studies should also focus on the green traits of the SHR varieties.