Optimal yield-related attributes of irrigated rice for high yield potential based on path analysis and stability analysis

Improvement of yield in rice (Oryza sativa L.) is vital for ensuring food security in China. Both rice breeders and growers need an improved understanding of the relationship between yield and yield-related traits. New indica cultivars (53 in 2007 and 48 in 2008) were grown in Taoyuan, Yunnan province, to identify important components contributing to yield. Additionally, two standard indica rice cultivars with similar yield potentials, Ⅱ You 107 (a large-panicle type) and Xieyou 107 (a heavy-panicle type), were planted in Taoyuan, Yunnan province and Nanjing, Jiangsu province, from 2006 to 2008 to evaluate the stability of yield and yield-related attributes. Growth duration (GD), leaf area index (LAI), panicles per m² (PN), and spikelets per m² (SM) were significantly and positively correlated with grain yield (GY) over all years. Sequential path analysis identified PN and panicle weight (PW) as important first-order traits that influenced grain yield. All direct effects were significant, as indicated by bootstrap analysis. Yield potential varied greatly across locations but not across years. Plant height (PH), days from heading to maturity (HM), and grain weight (GW) were stable traits that showed little variation across sites or years, whereas GD (mainly the pre-heading period, PHP) and PN varied significantly across locations. To achieve a yield of 15 t ha^-1, a cultivar should have a PH of 110–125 cm, a long GD with HM of approximately 40 days, a PN of 300–400 m^-2, and a GW of 29–31 mg.