Difference Research On Stem Base Structure Of Different Types Rice Of Indica-Japonica Differentiation

The related problems of culm traits, such as lodging induced by too high height, low rate of grain filling induced by blocked conducting tissue, are caused by the heterosis utilization between rice subspecies, therefore the study on the stem structure, especially the basal structure of traits, is beneficial to the effective utilization of rice heterosis. In this paper, using 16 wide sources indica and japonica rice as parents and breeding pedigree constructed using 37 types of different indica-japonica differentiation bred by Sanming institute of agricultural sciences as materials, the comparative analysis of difference of stem structural characters in different indica-japonica differentiation varieties and its relationship related to lodging resistance traits had been studied. Meanwhile, a set of genetic materials including parental lines and two generations of F1 was made with (12×4) incomplete diallel cross design by using restorer lines bred from 12 representative types of different indica-japonica differentiation and 4 main indica CMS line varieties in commercial production. The present study was designed to systematically analyze the genetic effects and heterosis of 5 structural characters in stem base, and genetic correlation between lodging resistance traits by using the methods of plant quantitative traits, the additive-dominance genetic model (AD model) and statistical method. The main results are as follows:1.The results of difference on stem base structural characters showed that the number of large and small vascular bundles in stem base in indica rice is larger than that in japonica rice. The ratio of the number of large and small vascular bundles, the coefficient of stem vascular bundles and the coefficient of cross section area in stem vascular bundle are increased gradually with decreasing of the japonica composition. The coefficient of stem vascular bundles and subspecific characteristics are closely related to the 10 cm stem (N segment for short) from the basal stem (at the level of mud) to above base. It can be used as a reference index for rice subspecies classification. The number of large and small vascular bundles, the ratio of the number of large and small vascular bundles in stem base in different indica-japonica differentiation varieties, and the coefficient of stem vascular bundles and the coefficient of cross section area in stem vascular bundle in intermediate indica-japonica differentiation type have high genetic stability. There is no difference in the number of large vascular bundles and the ratio of the number of large and small vascular bundles in the stem site in different indica-japonica differentiation varieties. But there are significant differences in the number of small vascular bundles, the coefficient of stem vascular bundles and the coefficient of cross section area in stem vascular bundle in the stem site in different indica-japonica differentiation varieties.2.The results of related studies on structural characters in stem base and lodging resistance traits showed that the smaller coefficient of stem vascular bundles, the greater japonica composition, the smaller lodging index, the greater area of elliptic cross section in stem vascular bundles; The correlations of the number of large and small vascular bundles with the force of anti-fracture, the area of elliptic cross section in stem, and the cross section area in stem wall in different indica-japonica differentiation varieties were significantly positive or very significantly positive; The correlation between the ratio of the number of large and small vascular bundles and the cross section area in stem wall was significantly positive; The correlations of the coefficient of cross section area in stem with lodging index, the area of elliptic cross section in stem were significantly positive or very significantly positive; In the combinations bred from restorer lines of different indica-japonica differentiation varieties, the smaller coefficient of stem vascular bundles, the greater cross section area in stem wall in base, the greater force of anti-fracture, the smaller the lodging index; The correlations of the difference value of the coefficient of stem vascular bundles in parents with transgressive heterosis and mid-parent heterosis in lodging index were very significantly positive. The correlations of the difference value of the coefficient of stem vascular bundles in parents with the force of anti-fracture and transgressive heterosis in cross section area in stem wall were very significantly negative. The correlations of the difference value of the coefficient of stem vascular bundles in parents with bending moment and mid-parent heterosis in the area of elliptic cross section in stem were very significantly positive.3.The results of related studies on genetic effects and heterosis in structural characters of stem base in different indica-japonica differentiation varieties showed that the two characters, the coefficient of cross section area in stem and the coefficient of stem vascular bundles in the 10 cm stem (M segment for short, the same below) from 10 cm to 20 cm height above ground, were mainly controlled by gene additive effect.5 structure characters in N segment and the characters in M segment such as the number of large and small vascular bundles, and the ratio of the number of large and small vascular bundles, were mainly controlled by gene dominant effect. Except that the narrow-sense heredity of the coefficient of cross section area in stem and the coefficient of stem vascular bundles in N segment in basal stem reached 0%, the narrow-sense heredity of the other structure characters were at the significant or very significant level. The predictive value of the population mean heterosis for the number of large and small vascular bundles, and the coefficient of cross section area in basal stem showed as a positive number, while the predictive value of the population mean heterosis for the coefficient of stem vascular bundles only in N segment showed as a positive number. The transgressive heterosis were negative for the ratio of the number of large and small vascular bundles in basal stem, positive for the number of large vascular bundles in M segment, and negative for the coefficient of stem vascular bundles in M segment.4.The results of related studies on genetic correlation analysis between structure characters and lodging resistance traits in basal stem in different indica-japonica differentiation varieties showed that the additive correlations of the plant height and lodging index with the number of large vascular bundles were mainly negative, and the additive correlation of the force of anti-fracture with the number of large vascular bundles was mainly positive; The dominant correlation of the plant height with the number of small vascular bundles was mainly positive, and in N segment the dominant correlation of the lodging index with the number of small vascular bundles was mainly positive and in M segment the additive correlation of the plant height with the number of small vascular bundles was mainly negative;The additive correlations of the plant height, the bending moment, the force of anti-fracture and cross section area in stem wall with the ratio of the number of large and small vascular bundles were mainly negative, and the dominant correlation of the lodging index with the ratio of the number of large and small vascular bundles in basal stem was mainly negative; The dominant correlations, in M segment, of the plant height, the bending moment, the area of elliptic cross section in stem with the coefficient of stem vascular bundles were very significantly negative. The additive correlation, in M segment, of the lodging index with the coefficient of stem vascular bundles in M segment was mainly negative; In N segment, the dominant correlations of the plant height, the bending moment, the area of elliptic cross section in stem with the coefficient of stem vascular bundles were very significantly positive.Except that the additive correlation of the lodging index with the coefficient of stem vascular bundles was mainly positive,the additive correlation of the lodging resistance traits with the coefficient of stem vascular bundles were mainly negative.