The Comparative Study On The Growth And Development Of Roots Of Naked Oats And Spring Wheat

This experiment was conducted in Zhangbei experiment station of Agricultural University of Hebei in Zhangbei county in 2003. Naked oats which is the main grain crop and economic crop and forage was used as experimental material with two varieties, Pin-5(late maturity) and Bayou-1 (early maturity), and spring wheat was used as control. The rule of growth and development of the roots of naked oats and spring wheat in mid-late period had been studied. The results were summarized as follows:1 Both early maturity and late maturity varieties, the rule of growth and development of roots of naked oats during the mid-late period was similar. The dry weight of roots reached their peaks at the heading and flowering period, and the early maturity variety was a few days earlier than that of the late maturity variety, then declined gradually, with the lowest value occurred at grain filling. After grain filling, the dry weights of roots increased slowly. The dry weights of roots of mature period is 104.85%~108.74% times as that of the grain filling period. In the late period of spring wheat, the rule of growth and development of roots was a single-peak curve, with the maximum occurred at flowering period, then the root biomass declined gradually, the dry weight of roots of mature period is 69.20% times as that of flowering period.Research on different soil layers of roots showed that, both early maturity and late maturity varieties, the roots of naked oats mainly distributed in 0-3 0cm soil layer, the ratio of the early maturity in this layer was 59.87%, which was a little lower than that of late maturity variety which is 63.61%. In the late period of naked oats, the root biomass in 0~30cm soil layer exhibited decreasing trend, but increased in 40~90cm soil layer. Compared with naked oats, the root biomass of spring wheat in 0~30cm was very little, the rate of which was 44.91%.2 Both early maturity and late maturity varieties, the change of the total volume of roots of naked oats in the mid-late period was consistent with that of the dry weight of roots. It can be divided into three stages, i.e. rapidly increasing stage (from jointing period to heading and flowering period), slowly declining stage (from heading and flowering period to grain filling period), and slowly rising stage (from grain filling period to mature period). That of spring wheat in late period was a single-peak curve, and the total volume of roots declined gradually after flowering.Comparative research on different layers of roots of naked oats and spring wheat showed that, the rate of the root volume in 0~30cm layer of spring wheat was 45.9%, which was a little lower than that of naked oats which was 57.7%~63.9%.3 Both early maturity and late maturity varieties, the root surface area decreased rapidly before heading. From heading to grain filling period, that of late maturity varieties declined rapidly, with the lowest value occurred at grain filling, and increased wavily thereafter. From heading to mature period, that of early maturity varieties appeared multi-peak curve. The root surface area of spring wheat was a single-peak curve in late period and declined gradually after flowering, which was harmful to grain filling. Considering the absolute amount, the root surface area of naked oats was larger than that of spring wheat, and that of late maturity variety was higher than that of early maturity of naked oats.Research on the root surface area of different soil layers showed that, the root surface area in 0-30cm soil layer decreased rapidly and changed not obviously below 30cm, that of spring wheat in 0~20cm soil layer decreased rapidly and changed not obviously below 20cm. This research showed that the deeper layer roots (30~90cm) played an important role in late period to the improving yield of naked oats and spring wheat.4 In the mid-late period of the two naked oats varieties, the trend of the content of total nitrogen was basically consistent, i.e. appeared declining trend with growing process. It included two stages, which were both decline...