晋东南旱地小麦生育规律特点及麦田水分供需平衡研究

研究表明,在以干旱为主要特点的气候条件下,晋东南旱地冬小麦生育特点是幼苗期长、有效生长期短、穗分化期短、灌浆期短、成熟晚;冬前分蘖多,春生分蘖少,分蘖高早、两级分化早而快,分蘖成穗率低.旱地冬小麦耗水特点是幼苗期少,拔节后增多,抽穗开花前后达到高峰,而后逐渐减少.麦田土壤水分供需不平衡,以拔节至灌浆期亏缺最严重,水分满足率仅50%左右,是开发小麦降水生产潜力的主要限制因素.旱地小麦耗水来源,幼苗期以降水为主,中后期以土壤供水为主.

STUDY ON THE ASPECTS OF DEVELOPMENT AND BALANCE BETWEEN WATER SUPPLY AND REQUIREMENT IN DRYLAND WHEAT IN SOUTHEASTERN OF SHANXI PROVINCE

Southeastern part of Shanxi Province is located on the hinterland of Loess Plateau, with warm temperate climate, fallen into subhumid by arid zone. The ecotype of wheat grown in this area belongs to the loess plateau ecotype in northern late-matured winter wheat zone. It is indicated by the investigation that the growth and development of winter wheat is characterized by "long seedling stage, short effective growing period, short panicle initiation stage, short grain-filling stage and late maturity" under the dry climatic conditions. The tillering characteristics are predominated by more tillers before winter, less tillers in spring, earlier tillering peak arrival, earlier and faster polarization and lower percentage of earbearing tiller. The contributions to grain yield have the characteristics of less number of ear, lower setting percentage, less grains per ear and lower testing weight of 1000 grains. The formula for number of leaves before winter versus accumulative temperature is Y=0.0117X-0.1095, that for number of spring grown leaves vs. accumulative temperature is Y=0.5445+0.0119X, for the remainder of total leaves on main stem vs. panicle initiation process is Y=8/1+ 10.0331e~(-0.9595x), and for the number of spring grown leaves on main stem vs. panicle initiation process is Y=8/1+10.361e~(-0.9515x). The characteristics of water consumption by winter wheat are lower in seedling stage, profound increasing occurs in elongation period, reaching to the maximum consumption around heading and flowering stages, and finally after that, getting less and less gradually. Mean water requirement within whole growing season is about 440 mm. But the actual water consumption averages about 325 mm, leaving behind 50-200 mm deficit, most seriously in elongation to grainfilling period when the water supply only meeting 50% of requirement. This is the major limitation for exploitation of wheat production potential of rainfall. The resources of water consumption by winter wheat on dryland are from rainfall during growing season and from soil water storage prior to planting, accounting for 70% and 30% respectively. At seedling stage, water supply is largely from precipitation, but later on from soil water conserved before. Soil water content drops after crop stem pushing, 0-80 cm soil profile being dried extremely, nearly approaching to wilting point. The moisture content in wheat field may be replenished to the level about what the bare field has during summer fallow period.