Influence of growth temperature on keeping quality traits of rose (Rosa hybrida L.) cut flowers grown under continuous CO₂ enrichment

An attempt was made to find out if there is any effect of higher than optimum growth temperature along with continuous CO₂ enrichment on the keeping quality traits of Rose (Rosa hybrida L.) cut flowers at harvest. Five rose cultivars, viz. ‘First Red’, ‘Arjun’, ‘Raktima’, ‘Raktagandha’ and ‘Pusa Pitamber’ were grown in phytotron and exposed to high (35/25C, T1) or optimum (28/18C, T0) temperature with enriched CO₂ (1000 mol mol⁻¹) until flowering. Cultivar means at T1 showed significant reduction in keeping quality parameters of flowering shoots in terms of number of days required from flower bud appearance to harvest (34%), stalk length (5%), number of petals (16%), flower diameter (24%), and fresh (17%) and dry (14%) weight of flowers compared to plants grown at T0. However, the vase life of cut flower was not affected by the pre-harvest growing conditions but there was significant cultivar difference. Among the cultivars, except Arjun, all other showed significantly higher number of stomata per cut flower at higher temperature. Days to harvest were significantly correlated with stalk length (0.472**), flower diameter (0.588**) and dry matter accumulation (0.52**) in flowers while it was negatively associated with the number of stomata per cut flower (−0.381*). This study indicates that CO₂ enrichment does not mitigate the effect of high temperature during growth of Rose plants and thus, does not improve the keeping quality traits of cut flowers at harvest. Hence, CO₂ enrichment in greenhouses during summers will not yield in good quality cut flowers.