油菜抗裂角性鉴定方法的改进及试验

Optimization and experiment of assessment method for pod shatter resistance in Brassica napus L.

为改进油菜抗裂角性鉴定技术,通过设计烘烤与不烘烤、烘烤后立即鉴定与密封保存隔夜后鉴定、不同摇床、震荡时间及钢珠数的单因素比较试验,分析了随机碰撞法鉴定油菜抗裂角指数的影响因素。结果表明,角果经80℃烘烤30 min并于室温封闭保存过夜后再鉴定,每震荡2 min记录一次裂角数,采用8个钢珠代替10个钢珠在HQ45Z恒温摇床上随机碰撞共10 min进行鉴定,可以显著提高鉴定结果的准确性和鉴定效率。通过比较改进前后随机碰撞法的鉴定结果,发现46份鉴定材料利用2种方法鉴定结果的相关系数为0.8844,相关性极为显著（P=3.705×10-16）。利用改进后方法鉴定的46份品种（系）,其抗裂角指数变异幅度为0-0.820,明显大于利用改进前方法鉴定结果的变异幅度（0.032-0.767）;且改进后方法鉴定结果的平均标准误差（0.0274）也明显小于改进前方法鉴定结果的平均标准误差（0.0348）,说明改进后方法提高了油菜抗裂角性鉴定的分辨率和准确性。研究为油菜抗裂角品种的选育和遗传研究提供技术依据。

Pod shattering is a serious problem for the production of rapeseed. Due to the lack of reliable and effective assessment methods, there has been little study on pod shattering. Therefore, it is very important to establish an accurate and readily available method to assess pod shattering for the development of pod shatter resistant lines. In order to establish a reliable assessment method, different methods for determining pod shatter resistance have been attempted. For example, a random impact test（RIT）, rupture test, baking dry method,dropping seeds counting, filed observations, and so on. None of the methods, however, was proven efficient and easy for use at a wide range. Pod shattering occurs when dehydrated pods are stimulated by an exoteric force, and it is influenced by many factors. The key factor contributing to pod shattering is the moisture content of the pods and the force orientation. To make a random impact test more accurate and advantage, the effects of the moisture content of pods, impacting conditions on determination accuracy were analyzed. Measures such as using pods stored in an airproof bag overnight after being baked at 80℃ for 30 minutes to equilibrate moisture, recording cracked pods after every two minutes shaking rather than every one minute, as well as reducing the number of impact steel balls from 10 to 8 could increase the accuracy and efficiency of the assessment, and resulted in a more reliable distribution of the pod shatter resistance index（SRI） within a certain amount of materials. To verify the advantage of the modified parameters, forty-eight lines were assessed by RIT before or after modification.Results showed that the average value of pod SRI was 0.270, ranging from 0.032-0.767, and with a standard error of 0.0348 assessed using RIT before modification, whereas when assessed using RIT after modification, the figures were 0.272, 0-0.820, and 0.0248, respectively. The distribution of pod SRI in ranges of 0-0.1, 0.1-0.2,0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.8, and 0.8 were 8, 11, 10, 9, 3, 2, 1, 2, and 0 assessed using RIT before modification, whereas assessed using RIT after modification, the figures were 10, 10, 9, 4, 6, 5,1, 0, and 1, respectively. The pod SRI determined by the two procedures was significantly correlated with a correlation coefficient of 0.8844（P=3.705×10-16）. In conclusion, the modified version of the random impact test method possesses advantages to the same method before being improved in terms of repeatability, accuracy, and efficiency, so it can discriminate the levels of pod shatter resistance among exiting rapeseed varieties, and is very suitable for use in selection of pod shatter resistant lines in rapeseed breeding programs and quantification of pod shattering of lines involved in genetic and molecular studies.