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【目的】耐荫性是影响间套作大豆产量的重要因素,影响大豆间套作模式的应用与推广。建立高效、通用、稳定的耐荫性鉴定体系,以利于发掘耐荫种质,开展耐荫性育种。【方法】以60份不同耐荫性类型的大豆品种为材料,首先对15%、30%和60%3个遮光度下倒伏品种比例等进行比较,确定遮光处理条件;其次对遮光后的株高、平均节间长、叶柄长和茎叶鲜重等17个性状进行筛选,选定耐荫鉴定指标;再比较播种后第40、50和60天3个时期耐荫指标的误差变异系数和表型变异系数等,明确鉴定时期,最后建立由遮光度、耐荫鉴定指标和鉴定时期构成的耐荫性评价体系;利用该体系对中国南方十二省区453份材料进行耐荫性鉴定和资源筛选。【结果】30%遮光度相对其他遮光梯度较优,表现为倒伏品种有而不太多(22%)、表型变异系数较高(25%)、品种间区分度较好。株高和平均节间长构成的耐荫指标相对其他指标具有以下优点:(1)较准确,误差变异系数低(9.36%),遗传率高(95.43%);(2)较稳定,环境间相关系数高(0.92);(3)品种间区分度较好,表型变异系数(31.25%)和遗传变异系数(30.52%)较大;(4)与田间目测耐荫级别相关性较高(0.73),较能反映田间实际情况。播种后50 d时相对其他时期耐荫指标各参数均最优,如环境间相关系数最大(0.87),误差变异系数最小(7.75%)。据此将30%遮光度条件下,播种后50 d株高和平均节间长相对值的平均数定为耐荫指数,指数越小则越耐荫。中国南方453份大豆耐荫指数的变幅为1.11—2.61,平均1.55,材料个体间差异极显著,且遗传率较高(91.13%),说明表型选择具有较高的准确性。Ⅲ、Ⅳ、Ⅴ和Ⅵ生态区内耐荫指数变幅分别为1.19—2.08、1.17—2.61、1.27—2.37和1.11—2.54,均存在大量的耐荫性变异,各生态区均有耐荫性材料。地方品种和育成品种耐荫指数变幅分别为1.11—2.61和1.17—2.54,都存在较丰富的耐荫性变异,在筛选出的11份耐荫资源中,有8份是育成品种,说明大豆育种过程中耐荫性已得到改良。【结论】由30%遮光度、播种后50 d的株高和平均节间长构成的耐荫指数是相对准确、稳定、灵敏、实用的耐荫性评价体系。中国南方大豆耐荫性存在较为丰富的变异,从453份南方材料中筛选到11份耐荫性强的种质资源。
【Objective】 Shade tolerance is an important factor that affects intercropping soybean yield and affects the application and popularization of soybean intercropping model. The establishment of efficient, universal, stable shade tolerance identification system in order to facilitate the development of shade-tolerant germplasm to carry out shade-resistant breeding. 【Method】 Sixty varieties of soybean varieties with different shade tolerance types were used as materials. The proportion of lodging varieties under 15%, 30% and 60% shading was compared firstly to determine the conditions of shading treatment. Secondly, 17 varieties were screened and their tolerance index was selected. The coefficient of variation of shade tolerance index at the 40th, 50th and 60th day after sowing were compared with Phenotypic variation coefficient and so on, so as to clarify the identification period. At last, the evaluation system of shade tolerance consisting of shading degree, shade tolerance index and identification period was established. By using this system, 453 materials in south China’s 12 provinces were evaluated for shade tolerance and Resource screening. 【Result】 The results showed that 30% of shading had better light shielding gradients compared with other shading gradients. The results showed that there was not too much (22%) of lodging varieties, and the coefficient of phenotypic variation was higher (25%). The shade-tolerance index formed by plant height and average internode length has the following advantages compared with other indexes: (1) more accurate, the coefficient of variation of error is lower (9.36%) and the heritability is higher (95.43%); (2) The correlation coefficient was high (0.92). (3) The differentiation degree among cultivars was better, and the coefficient of phenotypic variation (31.25%) and genetic variation coefficient (30.52%) were higher. (4) 0.73), more able to reflect the actual situation in the field. At 50 days after sowing, the parameters of shade-tolerance index were the best at other times, such as the highest correlation coefficient between environments (0.87) and the smallest error variance coefficient (7.75%). According to this, under the conditions of 30% shading, the average of the relative height of 50 days after sowing and the relative internodes length was taken as the shade-tolerance index, and the smaller the index, the more shade-resistant. The shading index of 453 soybean in South China was 1.11-2.61 with an average of 1.55. There was a significant difference between the individuals of the materials and the high heritability (91.13%), indicating that the phenotypic selection had high accuracy. The range of shade-tolerance index in the ecotopes of Ⅲ, Ⅳ, Ⅴ and Ⅵ was 1.19-2.08, 1.17-2.61, 1.27-2.37 and 1.11-2.54, respectively. material. The variation range of shade index of local cultivars and cultivars were 1.11-2.61 and 1.17-2.54, respectively. All of them had abundant variation in shade tolerance. Among 11 selected shades of shade-tolerant resources, 8 were bred varieties, indicating that soybean The shade tolerance has been improved during breeding. 【Conclusion】 The shade-tolerance index formed by 30% shading, plant height and mean internode length 50 days after sowing is a relatively accurate, stable, sensitive and practical shade-tolerance evaluation system. There were abundant variations in shade-tolerance of soybean in southern China, and 11 high-shade tolerance germplasm resources were screened from 453 southern materials.