小麦冷源及其在干旱条件下的适应性

Wheat cold source and its adaptability under drought conditions

冷型小麦具有代谢功能较好、活力较旺盛、抗早衰能力较强的特征 ,因而 ,培育出越来越多的冷型小麦并将其推向生产对于小麦的高产、稳产具有十分重要的意义。在这样的形势下 ,小麦冷源的发现明显促进了这一进程。小麦冷源是一种能够传递冷温特征的新遗传源 ,各种温度型的小麦与之杂交后 ,其后代降温的频率较高 ,且在这些降温的材料中能够涌现出较多的冷型小麦 ,从而有力促进了冷型小麦的选育。为了抵御干旱对小麦生产的严重威胁 ,进一步对冷源和非冷源材料进行了干旱适应性试验。通过对比发现 ,两者在一些重要内、外性状上 ,如叶片功能期、叶绿素含量、可溶性蛋白质含量、超氧化物岐化酶 ( SOD)活性、过氧化氢酶 ( CAT)活性、净光合速率和籽粒饱满指数等方面 ,小麦冷源较非冷源明显为优 ,表现出干旱胁迫下亦具有代谢好、活力强的特点 ,无疑 ,这就进一步拓宽了小麦冷源的应用范围 ,提高了它的研究和生产实践价值 ,可望借助这个新的遗传源 ,加速适应于干旱条件的优良品种的培育 ,其前景将会十分广阔。

Through study on the canopy temperature and some other traits of wheat for 10 years and more, the authors found that all of the wheat materials in any agro-ecological zone could be divided into three microclimate ecological types based on their canopy temperature (plant temperature), that was, cold, intermediate and warm types. The canopy temperature of cold type wheat was equivalent to or continuous lower than that of the control and its metabolic function, premature senility resistance and vitality were better than that of the control. On the contrary, warm type wheat had a continuous higher canopy temperature than that of the control and its metabolic function, premature senility resistance and vitality were also worse than that of the control and cold type wheat. For the intermediate type wheat, its canopy temperature, metabolic function presented a obvious polymorphism, that was, its characters mentioned above were unstable and were affected by the environmental conditions, especially the meteorological conditions and fluctuated between the characters of cold and warm type wheat. Intermediate type wheat had played a main role in wheat production for a long time. Obviously, cold type wheat was superior to intermediate and warm type wheat in metabolic function and kernel-filling. Therefore, It is very important and significant for wheat's high-and stable-yield to breed more and more cold wheat varieties and apply them in wheat production. In this case, the discovery of wheat cold source promotes remarkably the progress in cold type wheat breeding. Wheat cold source is a new kind of germplasms, when crossed it with other wheat materials, over 80% combinations of F1 hybrids presented a drop of canopy temperature and more than 30% of the combinations turned into cold type wheat in our experiments. So the metabolic functions of the progenies derived from wheat cold source have been improved greatly and the breeding of cold type wheat has been promoted obviously. There is a large range of arid area in China and wheat production is threatened by drought frequently in this area and even in non-arid area. It has been well known that wheat cold source can transfer a lower temperature traits to its progeny. However, whether it is resistant to drought needs to be investigated. If the application of wheat cold source in the breeding program could increase the chance of selecting drought-resistant varieties with excellent metabolic function, it would have a greater significance in wheat breeding. For this purpose, the authors of this paper established a severe drought microclimatic circumstances (soil moisture content was 9.3%, 10.9%, 11.8%, 12.9% and 13.2%, respectively, approaching blighting moisture at the depth of 0～20cm, 20～40cm, 40～60cm, 60～80cm and 80～100cm underground) and launched out into a comparative experiment on the characters of wheat cold source and non-wheat cold source for three consecutive years and leaf functional duration, chlorophyll content, soluble protein content, SOD activity, CAT activity, net photosynthetic rate and kernel plumpness index were tested in this experiment. The results showed that a series of traits including plant vitality and drought resistance in wheat cold source were better than that of non-wheat cold source under drought conditions. Therefore, wheat cold source is an excellent new genetic source having important theory and practice meanings in wheat breeding and many good wheat varieties, suitable for drought conditions will be released by taking advantages of its strong genetic heritability in metabolic function and drought resistance. Wheat cold source will have a promising future.