Evaluation of Relationship of Germination, Vigor and Health of Cotton (Gossypium hirsutum) Commercial Cultivars Seed under Accelerated Ageing Conditions

Abstract

Introduction: Cotton is the most important fiber-oil seed crop. Seed germination, vigour and health are the most important aspects of cotton seed quality. In Iran, annual cotton seed requirement is near 4000 tones, half of which is delinted and half is provided as fuzzy seed and therefore infection of fuzzy seeds to seed borne disease pathogens is possible. Every year a part of produced cotton seed does not possess standard quality and is not certify for various reasons including infection with seed borne disease pathogens. Thereafter, this research was conducted in order to study the relationship among cotton commercial cultivars seed germination, vigour and health.Materials and Methods: Fuzzy seeds lots samples of Sahel, Varamin, Bakhtegan and Mehr cotton commercial cultivars with of 80, 90, and 95 percent intial germination ability (normal seedlings percent) produced at Golestan, Khorasan Razavi, Fars, and Ardabil provinces respectively underwent Standard germination and accelerated ageing tests. Final germination percent before and after accelerated ageing, normal seedlings percent after accelerated ageing, decayed seeds percent before and after accelerated ageing, mean germination time, seedling length, dry weight, seedling length and weight vigour indices after accelerated ageing were measured and the fungus on decayed seeds were determined by blotter test. Then, their average frequency was determined.Results: Sahel and Bakhtegan cultivars and seeds having the highest primary germination ability had the most final germination percent before accelerated ageing and Sahel cultivar seed with the highest and moderate initial germination had the highest final germination percent after accelerated ageing. Sahel cultivar seeds had the highest normal seedlings percent after accelerated ageing. The highest decayed seeds percent before accelerated ageing belonged to Varamin and Mehr cultivars with moderate and low intial germination ability, and the highest decayed seeds percent after accelerated ageing belonged to Varamin and Mehr cultivars with low intial germination ability. Seeds having the lowest primary germination ability had the highest mean germination time and Sahel cultivar seeds had the highest seedling length and weight vigour indices. All studied cultivars seeds had been contaminated with Fusarium spp., Alternaria spp., Aspergillus spp. and Trichothecium roseum. Also, Varamin and Mehr cultivars seeds had the highest and Sahel cultivar seeds had the lowest average frequency of fungus on decayed seeds. Final germination percent before and after accelerated ageing and seedling length and weight vigour indices had significant negative correlation with decayed seeds percent before and after accelerated ageing. Conclusion:Seeds decay was the most important factor of studied cotton cultivars seed deterioration and germination and seedling vigour decrease. Sahel and Mehr cultivars seeds and seeds with the highest (95 percent) and lowest (80 percent) intial germination ability seeds respectively had the highest (...