冬小麦不同单位根的功能及分组的研究

应用(15)~N示踪技术研究了冬小麦不同单位根的特性、功能及对产量构成因素的影响。不同单位根的根干重、根长度及吸(15)~N量等,由下而上依次减少。各单位根吸收(15)~N后,蘖根之间,蘖蘖之间皆可互相运转,但其运转比例不同,其功能模式是:(15)~N喂全株根或专喂初生根,则先供给主茎,其次是分蘖,而且随蘖位升高而递减;喂n单位根,则先供给n单位本身(包括主茎),其次是n+2或n-2单位的蘖(同侧蘖),然后是n+1或n-1单位的蘖(对侧蘖),最后是未喂(15)~N的根系。依照各单位根的功能,小麦根可分为3组:初生根组、次生根下位组和次生根上位组。各组根吸收肥料氮量占总氮量的百分比分别是26.7％、31.4％和41.9％。各组根的主要功能是:初生根组在小麦一生中都起重要作用,但主要是促进冬前分蘖;次生根下位组对巩固分蘖,促进穗部发育起主要作用;次生根上位组对提高结实率、籽粒灌浆起决定作用。

STUDIES ON THE FUNCTIONS OF DIFFERENT UNIT-ROOTS AND THE GROUPING OF ROOTS IN WINTER WHEAT

The characteristics and functions of different unit-roots and their effects on the yield components in wheat were studied by means of unit-root 15N tracing technique.The root grouping was made by cluster analysis according to the function of different unit roots.The results were as follows:The unit-roots characters (weight, length etc. ) and 15N absorption decreased progressively downward. 15N absorbed by any unit roots could be transported from root to tiller and from tiller to tiller, but the transporting ratio was different.The pattern was as follows: when 15N was offered to total roots of plant or only to primary roots, it was transported to main stem and then decreassingly to tillers from lower unit to upper one, when 15N was offered to n unit-root, it was transported to n unit tillers ( incuding main stem), then to n + 2 or n-2 unit tillers ( same side tillers) , followed by n + 1 or n -1 unit tillers (opposite tillers) , and finally to other unfeed roots.According to the function,the wheat roots could be divided into 3 gr-oups:primary root group,lower secondary root group and upper secondary root group.The ratio of 15N absorption to the total N absorption in each group was 26.7%, 31.4% and 41.9% respectively.The difference among the three groups were that the primary root group functioned throughout whole life of wheat, mainly promoting tillers and increasing root numbers before winter; the lower secondary root group played the major role in strenthening tillers and promoting ear development; the upper secondary root group had the main function in determining the floret number, kernel number and kernel weight.