中文摘要：

【目的】测定西瓜果实中瓜氨酸含量,以期对西瓜种质资源总体瓜氨酸含量有较为全面的了解,为选育高瓜氨酸含量西瓜品种奠定基础。【方法】以195份西瓜种质资源为材料,用分光光度法测定成熟果实中瓜氨酸含量（以鲜质量计）,通过聚类分析将195份西瓜资源分为不同的类群,进行资源分类与筛选。【结果】195份西瓜种质资源的瓜氨酸质量分数为0.49-2.55 g·kg^-1,平均值为1.45 g·kg^-1,变异系数为0.30。呈近似正态分布,大多数品种瓜氨酸质量分数集中分布在0.84-2.10 g·kg^-1。聚类分析表明,195份西瓜种质资源可划分为4个类群[极低型（Ⅰ）、低型（Ⅱ）、高型（Ⅲ）、极高型（Ⅳ）]。白瓤西瓜主要集中在含量较低的Ⅰ类群;黄瓤、粉瓤、红瓤西瓜主要分布在瓜氨酸含量较高的Ⅲ类群中。黄瓤、粉瓤、红瓤3种瓤色西瓜瓜氨酸含量无显著差异,但显著高于白瓤西瓜品种。地方品种、选育品种以及从国外引进的固定品种主要集中在瓜氨酸含量较高的Ⅲ类群中;黏籽西瓜主要分布在Ⅰ和Ⅱ类群中;而野生西瓜和籽瓜则主要分布在含量极低的Ⅰ类群中。地方品种、选育品种以及从国外引进的固定品种瓜氨酸含量差异不显著,但均显著高于野生西瓜、黏籽西瓜和籽瓜。【结论】西瓜瓜氨酸含量与西瓜瓤色及类型有关,不同瓤色和类型西瓜的瓜氨酸含量差异可能是由于人们对西瓜的选择、驯化造成的。本试验筛选出了23份高瓜氨酸含量西瓜种质资源（包括14份选育品种、4份地方品种以及5份从国外引进的固定品种）,可作为选育高瓜氨酸含量西瓜品种的亲本材料。

英文摘要：

[Objective] L-eitrulline is a naturally occurring amino acid that functions in detoxification of catabolic ammonia and is a key element in the production of the vasodilator nitric oxide. Watermelon is considered to be a natural source of citrulline because of abundant eitrulline in the flesh and rind. With the improvement of people＇s living standard, functional foods have been highly valued, and watermelon varieties with higher citrulline have been bred. Studies have been carried out to quantify the content of eitrulline in different varieties with different ploidies and flesh colors, in different organs, and at fruit devel- opment stages. However, a problem in these studies is the lack of comparability of citrulline content because varieties evaluated were few and the studies were carried out at different growing environment in dif- ferent locations. In this study, the contents of citrulline in 195 watermelon accessions planted in the same location were measured. According to the eitrulline content level, the 195 accessions were divided into different groups, and then the distribution pattern of flesh color （white, yellow, pink, red） and watermelon types （wild watermelons, egusi watermelons, seed watermelons, the landraee eultivars, locally bred cultivars and introduced cultivars） in different groups were evaluated. Most of the traditional varieties （wild watermelons, egusi watermelons, seed watermelons, and the landrace eultivars） have been replaced by hy brids and new cultivars with higher productivity and strong tolerance. Therefore, in this study, the 195 wa- termelon accessions were evaluated in order to recover the use of some varieties and thus increase agro- biodiversity and to screen some excellent varieties for breeding cultivars with high citrulline content. [Methods]The plants of the 195 watermelons were planted in Henan province under the same condition. The central flesh tissue from ripe fruits was used to measure the citrulline content. The tissues sampled were immediately froze