林木存在遗传负荷高、世代周期长等一些特殊的生物学特性，开展林木复杂性状遗传解析一度被视为遗传学研究的难点。基础研究的滞后，严重阻碍了林木遗传改良研究进展。分子育种是突破林木长育种周期的关键技术,而定位与克隆控制重要性状的主效基因, 是开展分子育种的前提和基础。生物量产量是森林生产力重要评价指标，提高生物量产量是林木遗传育种的重要目标之一。生物量产量性状是典型的数量性状，受多基因控制。同时，林木是多年生物种，QTL的效应取决于其生长过程中长期表达的累积。本项目拟以成花期短、个体小的簸箕柳为研究材料，针对生物量产量，利用大规模高世代群体，开展多年度的QTL分析研究，查找主效QTL，阐明QTL随不同发育年龄的效应变化，完成主效QTL的局部区域精细定位，并利用簸箕柳基因组序列，开展目标基因区序列解析，找出控制簸箕柳生物量产量性状主效QTL的候选基因，为最终克隆控制簸箕柳生物量产量性状基因创造条件。

Trees possess some unique characteristics, such as high genetic load and long life span etc., which make it difficult to analyze the genetic loci underlying the complex traits in woody plants. The basic genetic study on trees lags behind that of the important crops, hampering the genetic improvements for trees. Molecular breeding is the key technique to break through the barrier of long breeding cycle of tree species. To carry out molecular breeding in tree breeding programs, locating and cloning genes underlying important traits is the basic demand and precondition. Biomass production is a key index for assessing the productivity of trees, which is also one of the important traits in tree improvement. Biomass production is a typical quantitative trait and is controlled by multiple genes. Since trees are perennial plants, the effect of quantitative trait loci (QTLs) depends on their consistent expression during the long growth process. In this study, we plan to use the early flowering small shrub willow (Salix suchowensis) as study material, focusing on its biomass production, to perform QTL analysis through multiple years based on the construction of large and high generation mapping pedigree. With these efforts, we aim to detect the large effect QTLs and explore their effect changing with different developmental ages, thereafter, to perform local fine mapping in the the large effect QTL intervals, and improve the mapping accuracy of these QTLs. Finally, we can confine the genome sequence in the target intervals by aligning the genetic map to the genome sequence of Salix suchowensis. Based on sequence dissection, we proprose to detect the candidate genes controlling the biomass production. This study will provide essential information for cloning the target genes in future studies.