不同秋眠级数苜蓿品种根颈变化特征分析

对秋眠级数分别为2,3,4和6的休眠和半休眠苜蓿品种生长前3年的根颈特性进行了连续研究.结果表明,不同休眠类型苜蓿品种间根颈特性差异明显,苜蓿根颈入土深度随着秋眠级数的降低而增加,其中,苜蓿播种后至第1次刈割是苜蓿根颈人土速率最大的时期.在温度较高的夏季,根颈增粗较快,而地上产草量较低.秋眠型苜蓿的二级根颈早于半秋眠类型苜蓿发生,在数量上多于半秋眠类型苜蓿.二级根颈主要产生于生长第2年及以后的第2和3茬生长期,在种植第1年及第1茬生长期并无二级根颈发生.品种间根颈分枝直径和根颈分枝数差异极显著.根颈直径、分枝数、分枝直径与苜蓿休眠性的关系未呈现规律性.

An alysis on dynamic variety of crown characteristics of different fall dormancy Medicago sativa cultivars

For 3 years we studied 4 Medicago sativa cultivars(CW200,Pondus,Grandeur and Victoria),whose fall dormancies are 2,3,4,and 6,respectively.The crown characteristics of the different fall dormancy M.sativa cultivars differed dramatically.The crown depth of the cultivars increased with a decrease of fall dormancy.The maximal velocity of crown depth was from planting time to the first harvest.The crown diameter rapidly increased in the warm summer,as the biomass growth rate reduced.The secondary crowns of fall dormancy cultivars were more numerous and appeared earlier than those of semi-fall dormancy cultivars.The secondary crowns grew in second and third stubble of planting second and subsequent years.Secondary crowns were not produced in the first year or first stubble.The difference of crown diameter and branches between cultivars was significant.Diameters of crowns,numbers and diameters of crown branches were not consistent with the fall dormancy scale.