The effect of chlormequat chloride (CCC) in relation to harvest time on seed and pod characteristics of four okra cultivars

Introduction: Chlormequat or chlorocholine chloride (۲-chloroethyltrimethyl-ammonium chloride, CCC) is an anti-gibberellin growth retardant (Sharma et al., ۱۹۹۸) that inhibits both cell division and cell elongation (Bode and Wild, ۱۹۸۴). The application of CCC to plants represses the growth of stems, leaves and stolons, but improves photosynthetic capacity by increasing leaf chlorophyll content (Huiqun et al., ۲۰۰۹). The aim of this research was to evaluate the effect of CCC on the pod and seed yield characteristics of four okra cultivars in relation to harvest time. Materials and methods: The present study was carried out at the Experimental Farm of the Benaki Phytopathological Institute during the growing season of ۲۰۲۲. Seeds of four okra cultivars ('Boyatiou', 'Veloudo', 'Pylaias' and 'Clemson') were sown in seed trays on ۱۳ May until field transplantation at the ۳-۴ true leaf stage ۲۰ days after sowing (۲ June). Chlormequat chloride (CCC) was provided by BASF S.E., Germany and applied to the whole plant by a hand sprayer at the following levels: C۱=۷۵۰ mg l-۱ C۲=۲۵۰۰ mg l-۱ C۳=۰ mg l-۱ (water, control). For acid scarification, sulphuric acid (۹۶%) for ۲۰ min was applied. For seed priming, salt solutions (NaCl) were prepared at concentrations of ۴ and ۸% in which ۱۰ g of seeds were soaked for ۱۲ or ۲۴ h. Results and Discussion: The results of this study indicated that chlormequat chloride (CCC) generally had no effect on seed germination across the cultivars, except for 'Veloudo' at a concentration of ۲۵۰۰ ppm, which appeared to enhance germination. Additionally, CCC did not significantly impact seed moisture content, though an increase in moisture content was observed in 'Boyiatiou' at ۳۵ and ۴۰ days after anthesis (DAA) in the C۱ treatment. CCC application consistently reduced plant height in all cultivars without significantly affecting flower induction, pod set, or the ۱۰۰-seed weight (Bode & Wild, ۱۹۸۴; Huiqun et al., ۲۰۰۹). Acid scarification and NaCl priming were effective in reducing hard seeds and improving germination rates, particularly in 'Boyiatiou' (Demir, ۲۰۰۱). The discussion highlights that cultivar differences relate to their specific genetic responses and growth conditions. For instance, 'Clemson' produced the highest number of flowers and pods, while 'Boyiatiou' had lower seed performance due to high percentages of immature and hard seeds at early harvests. The findings also show that harvesting at ۳۰ DAA resulted in lower germination rates across all cultivars, indicating seed immaturity. In 'Boyiatiou,' reduced moisture levels during seed maturation contributed to seed hardness, which was alleviated by six months of storage and acid scarification. These methods proved effective in enhancing germination, particularly for seeds susceptible to hardness (Passam & Rekoumi, ۲۰۰۹). Conclusion: The primary effect of CCC was to reduce plant height. There was, however, little or no effect of CCC flowering and pod set, hence yield. In cv. 'Veloudo' CCC (۲۵۰۰ mg L-۱) increased seed germination, but there was no effect of CCC at either ۷۵۰ or ۲۵۰۰ mg L-۱ in the other cultivars. Irrespective of CCC application, seed yield and quality are primarily determined by the genotype. Post-harvest seed treatments (scarification, priming) and seed storage may improve seed quality (germination).

کلیدواژه ها:

Chlormequat chloride (CCC) ، Okra cultivars ، harvest time