Study Of Identification Methods Of Brassica Oleracea L. Cold-resistance

Cruciferous brassica plant Brassia oleracea var.captiata is a kind of semi-hardy vegetables, the optimum growth temperature is15-25℃,and the optimum temperature of seed germination is18～25℃. Brassia oleracea seedling is weak in cold-resistance, it can tolerant low temprature5～2℃in a short-term. In recent years, the cultivation area of spring cabbage and open country winter cabbage is gradually increasing, so the requirement of cold tolerance Brassia oleracea is increase. There were large difference in different kinds of Brassia oleracea, and there were few reseach on cold-resistance identification of common head cabbage. In order to find the method of identification of Brassia oleracea cold-resistance, use cold-resistance germplasm resources effectively and provide theoretical bases on cold-resistance Brassia oleracea cultivation.40kinds of Brassia oleracea with differen cold-resistance were chosen in this experiment, and were trated in different tempreture. This experiment make a pilot study on physical signs and cold-resistance identification from Buds period to seedlingstage. The results as follows:1. Identification and screen in germination period of cold-resistance index:a. After differences significant analysis of germination period index of40kinds of Brassica oleracea,5index were reaching significant levels in different materials (relative germination rate at5℃, relative germination index at5and10℃, relative vigor index at10℃, The relative growth rate of radicle which trated6d at2℃, Root activity slewing rate wich trated6d at2℃), so these5index can be used for evaluation of germination period cold-resistance.b. In order to Make up for unilateralism which caused by a single index, Membership function were use for comprehensive evaluate cold-resistance. After screening,3strong cold-resistance material were found (NH39NH30NH28);3medium cold-resistance material (NH05. NH35. NH09);3very weak cold-resistance material (NH01. NH21. NH34).2. Identification and screen in seedling stage of cold-resistance index:a. Chose9kind of seedling stage Brassica oleracea as material, and treated by artificially low temperature stress. Significant correlation analysis were used after index determination,5index were screened for identification of seedling stage cold-resistance (Seedling morphological index, Half lethal temperature, the decline of chlorophyll, POD enzyme activity slewing rate, Root vigor).b. Membership function were use for comprehensive evaluate cold-resistance, this result isn’t consistent with single index result. Comprehensive analysis of seedling stage were chosed because of its higher credibility.