GENETIC DIVERSITY AMONG Calotropis procera (Aiton) WT Aiton GENOTYPES ACCORDING TO SEED PHYSIOLOGICAL QUALITY

ABSTRACT Characterizing genetic diversity based on evaluations involving germination and seed vigor, is a fundamental stage in starting the development of a cultivation system for Calotropis procera. Thus, this study aimed to estimate genetic diversity among 35 C. procera genotypes based on germination and vigor of seeds stored for 1 year. The genotypes, which originated from areas in Paraíba (Brazil), where they occur naturally, were collected and stored in March 2014. In order to evaluate the physiological potential of the seeds, two experiments were conducted between March and April 2015. The first involved a propagation test conducted in a germination chamber, while the second involved an emergence test in washed sand, performed in polyethylene trays in a screened environment under uncontrolled conditions. In both experiments, an entirely randomized design was used, with four repetitions of 25 seeds per genotype. The characteristics evaluated were germination, average daily germination, daily germination speed, the speed of germination index, the plantlet vigor index, emergence, the speed of emergence index, total length, and total dry mass. The results showed that genetic variability exists among the C. procera genotypes for variables involving germination and vigor of seeds stored for 1 year. Also, emergence, total dry plantlet mass, and germination characteristics contribute most to the genetic divergence among C. procera genotypes.

摘要 基于发芽与种子活力评价开展遗传多样性表征，是牛角瓜（Calotropis procera）栽培体系开发启动阶段的核心环节。为此，本研究以贮藏1年的种子为材料，对35份牛角瓜基因型的遗传多样性进行评估。供试基因型均采自巴西帕拉伊巴州的自然分布区域，于2014年3月完成采集与贮藏。为评价种子生理潜力，本研究于2015年3—4月开展两项试验：其一为发芽箱内的发芽试验，其二为在非受控环境下的遮阴环境中采用聚乙烯托盘装填水洗砂进行的出苗试验。两项试验均采用完全随机设计，每份基因型设置4次重复，每次重复包含25粒种子。本研究测定的指标包括发芽率、日均发芽数、日发芽速率、发芽指数速率、幼苗活力指数、出苗率、出苗指数速率、幼苗总长度及总干质量。结果表明，贮藏1年的牛角瓜种子在发芽与活力相关性状上存在显著遗传变异。此外，出苗率、幼苗总干质量及发芽相关性状是导致牛角瓜基因型间遗传分化的主要贡献因子。