紫花苜蓿品种间根系发育过程分析

从根系发育角度分析了不同紫花苜蓿品种在甘肃黄土高原丘陵沟壑区的适应性．研究表明：品种间侧根发生总数差异较大，Ameristand201和Sandili均为14个，陇东苜蓿(Longdong)仅为6个，65％的侧根发生于营养生长阶段；品种间主根生长，根系体积、根系生物量的积累在各个生育期的表现分为3种类型，Ameristand201，Sandili，Ameri-graze401在整个生育期内的生长速率较快，且速率基本保持一致；陇东苜蓿，Derby，Sitel在整个生育期内生长速率较慢，但在盛花期(7月中旬)后，生长速率急剧增加；Goldenempress，Defi，Algonqiun介于前两者之间．从根系发育过程分析，Amefistand201，Sandili，Amerigraze401对黄土高原丘陵沟壑区的季节性降水反映相对迟钝，在干旱半干旱生境中具有较好的适应性．

ANALYSIS OF ROOT SYSTEM DEVELOPMENT PROCESS OF SEVERAL ALFALFA (MEDICAGO SATIVA) CULTIVARS

A field experiment was conducted in hill and valley region of the Loess Plateau in Gansu Province to analyze root system development process of some alfalfa (Medicago sativa) varieties. Eight introduced varieties and a local one were arranged to estimate their adaptivity in semi-arid and arid regions of the Loess Plateau from the view of root system development process in the same site. Most secondary roots, taking of 65%, of several alfalfa varieties grew mainly from the taproot in the vegetative stage, but the total amounts of secondary roots of the varieties were different. The amounts of Sandili and Ameristand 201 were the biggest and that of Longdong alfalfa was the lowest. The increases in taproot length, root system volume and root system biomass were different among nine varieties. Biomass increasing rate, of Sandili, Ameristand201 and Amerigraze401 were fast, and smooth in every vegetative stage. The rates of Longdong, Sitel and Derby were slow before flowering stage, and were dramatically fast later in middle of July when plenty of rainfall was obtained. The rates of Goldenempress,Defi,Algonqiun were slower than these of Sandili and Ameristand 201 and Amerigraze 401, but faster than these of Longdong, Sitel and Derby. The study indicated that Sandili, Ameristand 201 and Amerigraze 401 were suitable to be sown in the hills and valleys of the Loess Plateau because they were more sensitive to water environment. Fig 3, Tab 1, Ref 24