Studies On Soil Moisture Index For Seedling Establishment With Drought Resistance Of Main Crops In North-west Of Hebei Plateau

Soil moisture is the key factor which effects crop seeding emergence and seedling after planting. In north-west of Hebei plateau, the wate resource is rarely and the rainfall is uneven distribution, so the crop`s germination and seedling vulnerable to the impact of water stress, therefore, how to ensure that crop`s germination and seedling under conditions of low soil moisture become an important problem which produce some effection to agricultural production and food security issues. In the research, using sandy chestnut soil as the experimental soil,which was accounted for 2/3 of whole cultivated area in north-west of Hebei plateau and using Maize,Red Kidney Bean,Naked Oats,Flax and Millet as the tested materials,to study effection on germination rate,seedling rate,the velocity of emergence,dry matter quantity and root-shoot ratio of the five crops under different soil moisture. The main results were as follows:(1) For different crops, the lowest soil moisture for crop germination is different. When soil moisture is less than 4.19%, the five kinds of crops are not emergence. When the soil moisture reach 4.53% ,the Maize, Red kidney beans, Millet emergence.When the soil moisture reach 5.34%, Naked Oats and Flax can emergence. 4.53% can be used as the lowest soil moisture for Maize`s, Red Kidney Bean`s and Millet`s germination. 5.34% can be used as the lowest soil moisture for Naked Oats and Flax`s germination.(2)The germination rate of the five crops under different soil moisture treatments increased with increasing soil moisture, but the higher germination rates are not with the higher soil moisture. Different crops have a certain water range of emergence, when the soil moisture beyond a cenrtain value, crop`s germination rate is no longer increased with increasing soil moisture, but there will be a downward trend.(3)The trends of five kinds crop`s seedling rate under the different soil moisture are similar to the trends of their germination rate,but the seedling rate is generally lower than the germination rate. The largest gap between the germination rate and the seedling rate under the different soil moisture appears in flax.The gap between the germination rate and the seedling rate of other crops is relatively small.(4) There is a certain threshold reaction in crops`germination rate on soil moisture, and the thresholds of different crops are not the same. In the experiment, the threshold of soil moisture is 6.27% in Maize, is 5.80% in Red kidney beans, and is 7.19% in Naked Oats, Flax and Millet.(5) The effection of different soil moisture on crops` velocity of emergence is remarkable. In the treatment of lower soil moisture, the crops have the longer time from the beginning of the emergence to the number of maximum. The higher the soil moisture is, the faster the crops emergence is, the more concentrated the crops` emergence time is, and the shorter the duration of the seedling is.(6) Under different soil moisture treatments, the trends of five crops` dry matter quantity and root-shoot ratio variation, but in general , with increasing soil moisture, the dry matter quantity increase, and root to shoot ratio downward.