Study On Indices Of Plant Type In Early And Middle Stages Of High Yielding Rice

3 Study on indices of plant type in early and middle stages of high yielding rice Postgraduate Sun Chengming Supervisor Professor Su Zufang (Yangzhou University ,Yangzhou 225009) ABSTRACT The experiments were carried out on the experimental field of Crop Cultivation and Physiology Key Laboratory, Yangzhou University from 1998 to 2000, and the relationship between indices of plant type in critical stage of effective tiller emergence, shooting stage, heading stage and yield was studied in population of different yield with mid-season rice Indica, cv. Shanyou 63 and Japonica, cv. Wuyungeng 8 as material .The main results were as follows. 1.Main indices ofplant type in early and middle stage of high yielding rice Critical stage of effective tiller emergence Leaf angel and length of plant were large and leaf loose degree was moderate. The sum of loose degree in top 3 leaves of Shanyou 63 and Wuyungeng 8 was 7.86 and 3.73, respectively. The average dry weight per leaf area in top 3 leaves was 3.8 to 3.9 around, and the leaf area per leaf sheath weight was small and dry weight per tiller was high. The transparence of middle and lower position in population was about 40-50%. Booting stage The leaf length was moderate. The leaf angle and loose degree of Shanyou 63 were smaller, and the sum of loose degree in top 3 leaves was 7.7 and the leaf area per leaf sheath weight was 0.36 to 0.38 cm2/mg. The leaf loose degree of Wuyungeng 8 was large, and the sum of loose degree in top 3 leaves was about 6.0 and the leaf area per leaf sheath weight was 0.27 to 0.34 cm2/mg. The transparence of the 35cm position from top in population was 40-50% and the photosynthetic rate of top 3 leaves was high. 4 Heading stage The plant height of Shanyou 63 was about 110cm to 115cm, and the length of basal internode was about 5cm. The plant height of Wuyungeng 8 was about 95cm to 100cm, and the length of basal internode was about 4.8cm. The relative height of top 3 leaves was higher and the leaves were more erect. the most leaf area per plant maintained the middle and upper position of the plant, and the Chlorophyll content of the plant was higher and the root vigor was strong. 2. The leaf loose degree and leaf area per sheath weight were the morphological and physiological indices of early and middle stages of rice. The loose degree was the best representative form of leaf space structure in early and middle stage of rice, which was gained from sine wave of leaf angle and length. When the leaf loose degree was properly increased and tended to a best value in N-n stage, the illumination could be strengthened and the dry weight of per tiller could be increased. The leaf loose degree was not the same in different variety in shooting stage, and it was appropriate that the leaf loose degree of Shanyou 63 was small, simultaneous, the leaf length was moderate and the leaf was erect. In this way, the upper space of plant could be fully utilized, and the photosynthesis could be promoted. The leaf length of Wuyungeng 8 was shorter, so that it was favorable to promote photosynthesis and dry matter production when the leaf loose degree was increasing.