Castor is a prime industrial crop belonging to a monotypic genus and its genetic improvement depends on creating desired variability in the primary gene pool. This study reports the development of tetraploid castor plants through colchicine treatment. Seeds of three castor genotypes were soaked in aqueous solutions of colchicine with variable concentrations, and the LD50 value was determined. Of 1010 treated field-raised plants, three were identified as potential polyploids based on increases in a guard cell size and reductions in the number of stomata. The putative polyploid plants were selfed and the progeny were subjected to meiotic analysis. All the progeny were found to be tetraploid. The pairing of chromosomes was abnormal with univalent to octavalent configurations during meiosis-I, but the later parts of meiosis were normal. Seasonal variations in pollen fertility indicated the possible role of temperature-sensitive male sterility in causing the sterility in tetraploid plants. The tetraploid plants were phenotypically comparable with their diploid counterparts, but produced substantially bigger seeds. Thus, these tetraploid plants are valuable resources for basic and applied research in castor.

中文翻译：

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四倍体蓖麻植物的开发和表征

蓖麻是属于单型属的主要经济作物，其遗传改良取决于在主要基因库中创造所需的变异性。本研究报告了通过秋水仙碱处理的四倍体蓖麻植物的发育。三种蓖麻基因型的种子浸泡在不同浓度的秋水仙碱水溶液中，LD50值被确定。在 1010 株经过处理的田间饲养植物中，根据保卫细胞大小的增加和气孔数量的减少，有 3 株被确定为潜在的多倍体。将推定的多倍体植物自交并且对后代进行减数分裂分析。发现所有后代都是四倍体。减数分裂-Ⅰ期染色体配对异常，单价至八价，但减数分裂后期正常。花粉生育力的季节性变化表明温度敏感雄性不育在导致四倍体植物不育中的可能作用。四倍体植物在表型上与其二倍体对应物相当，但产生的种子大得多。因此，这些四倍体植物是蓖麻基础和应用研究的宝贵资源。