Biomechanical Characteristics of Rape Stalks

[Objective] To study the correlation between the biomechanical properties of rape stalks and rape stem lodging. [Method] Through axial compression tests to the stalks of 4 different rape varieties, the change rules of maximum stem bearing ca- pacity, maximum compressive strength, elastic modulus and moment of inertia along plant height were analyzed, as well as the effect of different varieties and water contents on the biomechanical property indices of rape stalks. [Result] The maximum loads of rape stalks presented liner decrease trend along with the increase of stem height, and all reached the maximums below the height of 50 cm. The maximum stem compressive strength and elastic modulus of the 4 varieties were increased with ascending height, but in a slow rate with small change, thus the modulus of e- lasticity could be considered as unchanged. The maximum bearing capacity, maxi- mum compressive strength and elastic modulus of dry rape stalks were higher than wet stalks, indicating that the water contents of rape stalks had significant effect on their mechanical properties. According to the actual lodging situations in filed, stalks of variety No. 1 owned the worst biomechanical properties and lodging degree, while the biomechanical properties of No. 6 and F5 were better than No. 1 and No. 9, and they also had stronger lodging-resistance. [Conclusion] The study provides parameters and bases for the design of mechanized production and mechanical deep processing of crops, and can better reveal the physical natures of organisms. The methods used in this study can also be used to screen excellent crop stalks.

QTL Analysis of Lodging-related Morphological Traits of Soybean under Two Eco-environments

[Objective] This study is to map QTLs for lodging-related morphological traits of soybean, aiming at providing basis for breeding lodging-resistant varieties. [Method] To map the QTLs for lodging-related morphological traits, an F216-F218 RIL population containing 147 lines derived from a cross between Charleston as female and Dongnong 594 as male parent were used as experimental materials in this study. Totally 164 SSR primers screened out from amplification on two parents, were employed to amplify the F216-F218 RIL population for constructing a genetic linkage map. The QTLs for nodes on main stem, stem thickness and stem weight of the F216-F218 RIL soybean population were investigated in two eco-environments for three years. [Result] Sixteen QTLs for nodes on main stem were detected in A1, B1, C2, Dla, D2, F, G, H and N linkage groups, respectively; Ten QTLs for stem thickness in A1, B1, C2, Dla, E and G linkage groups, respectively; Fifteen QTLs for stem weight in A1, A2, C2, Dla, Dlb and G linkage groups, respectively. Of these QTLs, five for nodes on main stem, one for stem thickness and six for stem weight could be detected by both CIM and MIM, accounting for 8.6%-27.0%, 9.0%- 11.0%, and 6.0%-39.0% of the general phenotypic variation, respectively. From ex- perimental data of two years, Three QTLs for nodes on main stem and two for stem weight could be detected, accounting for 8.0%-60.2% and 10.0%-23.0% of the general phenotypic variation, respectively; while no QTL for stem thickness was re- peatedly detected during more than two years. [Conclusion] Comparison of the QTLs mapped for nodes on main stem, stem thickness and stem weight indicates that these three morphological traits are closely related with lodging-resistance of soybean.

大樱桃自由纺锤形三年成形管理技术

近几年来,自由纺锤形已成为大樱桃栽培的主要树形,但因该树形的整形技术要求较高,在管理中往往达不到所要求的树形.烟台农发大樱桃服务站与芝罘区农业技术推广中心,在大樱桃自由纺锤形整形工作中,做了一些探索性研究,达到定植3年成形.

Effects of Different Row Spacing and Planting Density on the Main Agronomic Characters and Yield of a Maize Variety Xianyu 335

A field test was conducted to investigate the effects of different row spac- ing and planting density on grain filling rate, yield and other agronomic characters of a maize variety Xianyu 335, thereby determining the optimum planting density for maize in the Huang-Huai-Hai region. The results showed that the grain filling rate of Xianyu 335 was tended to decrease with the increase of planting density, and un- der the same planting density, the grain fill row spacing. Under the planting density of spacing showed little effect on the kernels ng rate decreased with the increased 60 000 plants/hm2, changing the row per spike of Xianyu 335; under the planting density of 75 000 plants/hm2, with the increase of row spacing, the kernels per spike of Xianyu 335 decreased; and under the condition of same row spacing, the yield of Xianyu 335 under the planting density of 75 000 plants/hm2 was higher than that under the planting density of 60 000 plants/hm2. The yield of Xianyu 335 reached the highest level at the row spacing of 50 cm and （40 ＋ 80） cm.