【摘要】 <正> 一、发现西藏半野生小麦的经过情况及其分布地区 1974年青藏高原综合科学考察队从四川进藏,沿途进行了线路考察。在昌都专区察雅县吉塘区调查野生大麦时,藏族社员提供了半野生小麦的情况。它是一种在形态上很象小麦,而在成熟时穗轴折断的一种小麦,一般是做为田间杂草混杂在青稞与小麦田间。采集了植株标本和种子。当考察队到达西藏自治区农科所吋,得知自治区农科所程天庆、董玉鳌同志早在1962年曾在山南专区隆子县三安曲林采集到一种成熟时穗轴折断的小更多还原

【Abstract】 Semi-wild wheat has been discovered during the scientific expedition to Chin-zang plateau in 1974. A number of specimens were collected and analysed genetically and cytologically. Semi-wild wheat usually was grown as well as weed in barley and wheat field. The matured spikelets were freely separated from the spike and fallen on the ground, and thus sprouted naturally when conditions permitted. It was first discovered in Jitan district, Chajia county, Changdu prefecture and samples were collected later in Jiacha and Gunga counties while it was found in Longzi and Reubu counties also. Genetical study on spike row progenies of semi-wild wheat showed that the majority were stable with brittle rachis although segregation in this trait was found in a few lines. Semi-wild wheat could be grouped into various varieties and polymorphism was apparently demonstrated. The phylogenetic position of the semi-wild wheat in the evolution of wheat is theoretically an important problem and worths further investigation. Significant difference was observed between semi-wild wheat in Xizang and Triticum spelta. Spike of T. spelta has fragile rachis which usually disarticulates above the pedicel with an p-edicel attached to the ventral side of the spikelet, while that of semi-wild wheat in Xizang breaks below the pedicel, so that each spikelet is set on it’s own pedicel. The mode of disarticulation of rachis of semi-wild wheat is-similar to that of Triticum aestivum ssp.yunanncnsis, but the former is more primitive than the latter. Because in yunanncnsis the rachis will be broken when pressed with a little force, and in the semi-wild wheat it is separated freely into brittle spikelets at maturity which is rarely observed in hexaploid wheats. Observations of semi-wild wheat root tip squashes revealed 2n = 42, a hexaploid. It can be very easly crossed with common wheat, but sterile lines are sometimes segregated in offsprings, indicating probably some kind of interspecific isolating mechanism might occur. In practice, it can be used as a new source for hybrid wheat breeding. According to the above mentioned unique characteristics, we suggest that the semi-wild wheat could be established separately as a new subspecies of Triticum aestivum named tibetanum ssp. nov. Shao.更多还原