Abstract:

Huanghe-Huai River area is an important rice-growing area in China and most rice cultivars used there are mid-season japonica ones. Today, little is known what traits should be for a cultivar with super-high-yielding and good quality in this district. The purpose of this study was to elucidate the characteristics of plant type, grain yield and quality of rice cultivars grown in Huanghe-Huaihe River area. One hundred and twenty-nine mid-season japonica rice cultivars and lines, used in the production, were field-grown and their morphological traits, grain yield and quality were investigated. The results showed that, by cluster analysis based on grain yield, 129 tested cultivars could be classified into five groups: super-high-yielding (13.57 t ha^-1), high-yielding (11.52 t ha^-1), mid-yielding (10.26 t ha^-1), mid-low-yielding (9.04 t ha^-1)，and low-yielding (7.57 t ha^-1). In the total tested cultivars, super-high-yielding cultivars were 3.1%, low-yielding cultivars were 14.7%, and other cultivars were 82.2%. Most of high- and super-high-yielding cultivars had half-erect and large panicles and erect leaves, produced more biomass, and had greater seed-setting rate, grain weight and harvest index. The cultivars with good grain quality were mainly in the high-yielding and mid-high-yielding groups, and very few in the super-high-yielding and low-yielding groups. The higher percentage of chalky grains was a major problem for the super-high-yielding cultivars. The traits or indexes for a super-high-yielding mid-season japonica rice cultivars were suggested, i.e., plant height 100–108 cm, whole growth period 150–155 d, half-erect panicles, panicle length 0.17–0.18 m, panicles 320–340 m^-2, primary branches 12–15, secondary branches 30–38, spikelets per panicle 160–180, seed-setting rate>85%, 1 000-grain weight 26–27 g, the length of the flag leaf, and the 2nd and 3rd leaves from the top were 0.26–0.28, 0.35–0.40, and 0.32–0.38 m, respectively, the angle of the flag leaf<20º, and harvest index>0.5.

Key words: Rice, Plant type, Grain yield, Grain quality, Cluster analysis