Fig. 6: Overexpression of OSA1 increases grain yield and N use efficiency (NUE) in the field.

a–d Photographs of 100-day-old WT and OSA1-ox plants in the field (a), in pots in the field (b) and harvested panicles (c) and spikelets (d) in 2017 in northern Nanjing under 200 kg N ha⁻¹ (M–N) fertilisation. e Grain yield, f panicle weight per plant, g panicles per hill and h spikelets per panicle of WT and OSA1-ox plants in field tests at three locations (n ≥ 6). i Relative agronomic NUE in WT and OSA1-ox plants in field tests under low (L–N; 100 kg N ha⁻¹), moderate (M–N; 200 kg N ha⁻¹) or high (H–N; 300 kg N ha⁻¹) levels of N fertilisation. Columns and error bars represent the means ± SEs (n = 3). j Grain yield of WT and OSA1-ox plants in field tests under different N conditions. Black asterisks represent significant differences between WT and OSA1-ox plants under the same N fertilisation level; small circles in e–h, j represent data points of collected samples in individual experiments (n = 6 in 2017 Nanjing-N and n = 8 in 2016 Nanjing-S and 2017 Fengyang). Centre line indicates the median, upper and lower bounds represent the 75th and the 25th percentile, respectively. Whiskers indicate the minimum and the maximum in the box plots (e–h, j). Differences were evaluated using the two-tailed Student’s t test (*P < 0.05; **P < 0.01; n.s., not significant). The exact P values are provided in the Source Data file.