Simulation on Distribution of Photosynthetically Active Radiation in Canopy and Optimum Leaf Rolling Index in Rice with Rolling Leaves

By replacing leaf area index （LAI） with effective leaf area index （ELAI） through introduction of leaf rolling index （LRI）, the distributions of photosynthetically active radiation （PAR） in the canopies of three hybrid rice combinations, Liangyou E32 with high LRI, Liangyoupeijiu with moderate LRI and Shanyou 63 with non-rolling leaves （normal）, were simulated. The model based on ELAI could predict more accurately than that based on LAI. The PAR interception, conversion and utilization efficiency in the three combinations were studied to evaluate their optimal LRI and LAI. The PAR utilization efficiency of Liangyou E32 was lower due to excessive rolling leaves and less ELAI, and that of Shanyou 63 was also lower because of the faulty PAR interception and lower photosynthetic rate and saturation point at lower layer in canopy. Compared with the above two combinations, Liangyoupeijiu showed more appropriate distribution of PAR interception and conversion efficiency in canopy, and higher PAR utilization efficiency. The optimal LRI and LAI for Liangyoupeijiu were 0.11 and 7.6, respectively, which were close to the observed value, 0.11 and 7.9, respectively. However, the optimum LAI was 9.8 for Liangyou E32 and 6.2 for Shanyou 63, larger or smaller than those under the current plant density, which led to lower efficiency of PAR utilization. Besides, the optimum LRI for Liangyou E32 and Shanyou 63 were 0.12 and 0.08, respectively, which were close to the actual LRI for Liangyoupeijiu （0.11）.

Construction of SSR Linkage Map and Analysis of QTLs for Rolled Leaf in Japonica Rice

Genetic analysis of rolled leaf is important to rice ideotype breeding. To detect loci controlling rolled leaf of japonica restorer lines, SSR marker genotypes and phenotypes of flag leaf rolling index （LRI） were investigated in Xiushui 79 （P1, a japonica rice variety）, C Bao （P2, a japonica restorer line） and 254 recombinant inbred lines derived from the cross between P1 and P2 , and in two environments. A genetic map of this cross was constructed, QTLs for LRI were detected and their interactions with environments were analyzed. Among 818 pairs of SSR primers, 90 primers showed polymorphism between P1 and P2, and 12 markers showed highly significant correlation with LRI in both environments based on single marker regression analysis. The genetic map containing 74 information loci has a total distance of 744.6 cM, with an average of 10.1 cM between two adjacent loci. Three QTLs （qRL-1, qRL-7 and qRL-8-1） were detected with two softwares： WinQTLCart 2.5 and QTLNetwork2.0. qRL-8-1 was a new locus, accounting for 15.5% and 12.8% of phenotypic variations in the two environments, respectively. The phenotypic variation explained by additive effect was 6.6%. No interaction was found between qRL-8-1 genotype and environments.

Study on Photosynthetic and Physiological Effects of a Novel Adaxially-Rolled Character in Rice (Oryza sativa L.)

Objective] The main biological effects of leaf rol ing of rice was studied to provide the theoretical basis for the application of RL （t） in the breeding of the rice. [Method] A rice mutant with adaxial y-rol ed leaf was found in breeding, temporarily named as RL （t）. The differences were researched in which light interception struc-ture, light transmission photosynthetic efficiency and cel ular structure comparison between RL （t） and its sister lines that had flat leaf. [Result] Both leaf rol ing index and leaf erecting index of RL （t） were higher than those in 0731-3-1-1B. However, its basic leaf angle and leaf drooping angle were significantly lower than those in 0731-3-1-1B in upper three leaves, which caused a great raise in the photosynthetic rate on account of the light transmittance of RL （t）’s population were significantly higher than that of 0731-3-1-1B especial y the upper and middle part. The stomata conductance and the intercel ular CO2 concentration of the upper three leaves and transpiration rate of the flag and the second leaf were also significantly higher than that of 0731-3-1-1B. The bul iform cel s became smal er, leading to the rol ing up of leaves. [Conclusion] The study provided a theoretical basis for the principle of high-yielding breeding with the application of the adaxial y-rol ed leaf mutant in rice.

A new nonlinear force model to replace the Hertzian contact model in a rigid-rotor ball bearing system

A new nonlinear force model based on experimental data is proposed to replace the classical Hertzian contact model to solve the fractional index nonlinearity in a ball bearing system. Firstly, the radial force and the radial deformation are measured by statics experiments, and the data are fitted respectively by using the Hertzian contact model and the cubic polynomial model. Then~ the two models are compared with the approximation formula appearing in Aeroengine Design Manual. In consequence, the two models are equivalent in an allowable deformation range. After that, the relationship of contact force and contact deformation for single rolling element between the races is cal- culated based on statics equilibrium to obtain the two kinds of nonlinear dynamic models in a rigid-rotor ball bearing system. Finally~ the displacement response and frequency spectrum for the two system models are compared quantitatively at different rotational speeds, and then the structures of frequency-amplitude curves over a wide speed range are compared qualitatively under different levels of radial clearance, amplitude of excitation, and mass of supporting rotor. The results demonstrate that the cubic polynomial model can take place of the Hertzian contact model in a range of deformation.