【作者】 金辉；

【导师】 谢从华；

【作者基本信息】 华中农业大学 ， 蔬菜学， 2012， 博士

【摘要】 目前解决马铃薯因病毒侵染退化、提高单产的有效方法是繁殖和使用脱毒种薯,脱毒种薯能够大面积推广应用必须有优质、高效的种薯繁育体系作为保障。随着高效低成本繁育技术的不断发展,缩短种薯繁育年限,是种薯繁育体系发展的趋势。微型薯繁育是种薯繁育体系建设的重要环节,如何提高微型薯的繁殖系数,提高单位面积有效微型薯的数量,降低微型薯的生产成本,对种薯繁育体系的建设具有非常重要的意义。本研究围绕华中农业大学建立的以试管薯为核心的二年制种薯繁育体系中的微型薯生产这一环节,深入开展不同密度、不同季节以及不同种源生产微型薯的研究,探明在这三种因素下,植株的冠层发育、光能截获与转化、干物质生产与分配以及微型薯大小和分布的基本特征,其主要研究结果如下。1、微型薯大小分布符合负指数曲线。本研究以4个马铃薯品种,春秋2个生产季节,试管薯直播和试管薯母苗顶端扦插2种种植方式,观察了200粒(株)/m2、400粒(株)/m2和600粒(株)/m2三个种植密度下单位面积微型薯形成数量、块茎大小的变化。结果表明,一个微型薯群体中,随着块茎重量级别的增加,块茎数量逐渐减少。所有试验处理的微型薯大小分布均符合y=N(e-λbn-1-e-λbn”)的负指数方程(y为重量等级n的微型薯数量,N为单位面积的微型薯数量,e为自然常数2.71828,λ为微型薯平均重量的倒数,bn和bn-1分别为微型薯重量等级n的上限和下限),块茎大小的分布形式取决于单位面积块茎数量和块茎平均重量两个参数。2、种植密度通过增加单株数提高了单位面积的微型薯形成数量。不同品种在不同生长季节的结果表明,单株块茎形成数随密度增加有下降趋势,极差在每株0.5个左右,但其变异显著小于密度增加对单位面积块茎形成总数的影响,其极差在2倍左右,证明密度是影响微型薯形成数量的主要因素。3、种植密度通过调控块茎对光合产物的竞争影响微型薯平均重量。研究观察到,在所有试验处理中,植株干重与作物的累积光能截获量具有y=a+bx直线相关(y为植株干重；x为累积光能截获量)。不同品种的块茎干重分配率在75-85%之间,主要由品种遗传特性控制,不同密度间没有显著差异。因此,块茎干重与累积光能截获量也具有显著的直线相关。本研究证明,光能截获率与叶面积指数的相互关系符合Beer定律,高密度主要通过增加前期冠层覆盖率和叶面积指数增加了光能截获量。但光能累积截获量与块茎平均重量的相关分析表明,随着密度增加其斜率显著降低,说明单个块茎所获得的光合产物随密度增加而减少,提高密度增加了块茎间对光合产物的竞争。4、试管薯直播能有效提高微型薯的繁殖效率。相同密度下的试管薯直播,单位面积的微型薯数量、单株结薯个数、单株微型薯重量均大于顶端扦插,因而在微型薯生产中,可采用以试管薯直播为主、顶端扦插为辅的方式进行微型薯生产,能显著提高微型薯的繁殖效率,降低生产成本。5、本研究提出了微型薯生产的适宜技术。根据块茎大小分布模型及种植密度与块茎数量、光能截获量和微型薯重量的相互关系,按照对微型薯的大小需求确定适宜的种植密度,以提高单位面积有效微型薯的数量,从而降低微型薯生产成本。更多还原

【Abstract】 Virus-free seed potato is an effective measure to reduce yield loss resulted from virus infection. A shorter seed potato production system is of most importance in China’s agrisystem to ensure seed quality. The minituber efficiently produced under protected conditions has been proved capable to rapid seed potato propagation. However, obvious differences in minituber production efficiency have been reported widely. To look into the factors influencing number of tubers formed and tuber size, impacts of growing methods and plant density were investigated in spring and autumn seasons. The main results are as follows.1. Tuber size distribution of minitubers follows a negative exponential curve. With4potato varieties which were grown from microtubers and tip-cuttings of the microtuber plants under protected conditions of spring and autumn seasons, the number of tubers formed and tuber weight were investigated at plant densities of200,400and600microtubers or plants/m2. The results showed that number of tubers decreased as tuber weight category increasing, which could be represented as y=N(e-λbn-1-e-λbn)(where, y is the number of tubers of weight category n, N is total number of tubers per unit area, λ stands for the reciprocal of mean tuber weight, bn and bn-1are upper and lower limit of tuber weight category n, respectively, and e is the natural constant2.71828). The distribution pattern is determined by two parameters, total number of tubers and mean tuber weight.2. Plant density is a main factor controlling number of tubers per unit area. In different growing seasons, it was observed that tuber formed per plant was decreased in each variety tested as plant density increased, the maximum difference was about0.5tubers/plant. However, the total number of tubers formed per unit area was about2folds between the highest and lowest densities, suggesting that the minitubers produced largely related to the plant density.3. Competition between tubers for photoassimilates, which is elevated as plant density increasing, is causal for mean tuber weight. The results demonstrated that, for all the experimental treatments, there was a linear relationship between plant dry weight and accumulated radiation interception of the crop, which followed a formular of y=a+bx (where, y is plant dry weight while x stands for accumulated radiation interception). The dry matter partitioning rates among the varieties tested were between75-85%with a genotype-dependent feature, but no obvious difference existed between plant densities. Consequently, similar relationship was established between tuber dry weight and accumulated radiation interception in present research. The results also showed that the relationship between leaf area index and percentage of radiation interception fitted well to the Beer’s Law. The higher plant density had a larger radiation interception in early stage of plant growth in comparison with the lower plant density. However, a smaller value of the slope, calculated for the correlation between mean tuber weight and accumulated radiation interception, was accompanied with higher plant density suggesting a less amount of photoassimilates transmitted to the tubers of higher plant density than that to the tubers of lower one.4. Microtubers are super over tip-cuttings for improving the production efficiency of the minitubers. The number of minitubers harvested, tubers per plant and mean tuber weight were higher in the crop grown from microtubers than the crop of tip-cuttings for all the varieties investigated. It is feasible, therefore, to produce minitubers mainly with microtubers and complemented with tip-cuttings for the sake of enhancing productivity and minimizing the production cost.5. The findings of present research are informative for optimal minituber production. Based on the tuber size distribution model reconfirmed and the relationships established between plant density and tuber formation, radiation interception and tuber weight, an optimal plant density for specific variety can be estimated by given a desired tuber weight to produce more sized minitubers with reasonably lower production cost.更多还原