Effect of Calcium Chloride, Cytokinin and Abscisic Acid on Growth of Rose Cut-flower (Rosa hybrida)

Abstract

Rose (Rosa hybrida) is a popular and extensively cultivated cut flower amongst commodities in the floriculture industry.However, there has been an increase in losses both in quantity and quality of cut roses which has significantly affected the production and return on investment. The highest loss reported has been at 18.87% at the producer level. These losses have been attributed to inadequate adaptability under circumstances involving humidity and temperature extremes, leading to high respiration, rapid cell disintegration and loss of aesthetic value of cut rose. This study therefore, investigated the effect of calcium chloride, cytokinin, and abscisic acid on the growth of tea hybrid rose, Rhodos variety. The study was cultivated over two flushes, August 2023- November 2023 and November 2023-January 2024 in Redlands Roses PLC, in Ruiru, Kiambu County. The field experiment was laid out in RCBD. There were 10 treatments including non- application (control); CaCl2 (250, 500 and 750 mg/L), CKs (150, 250 and 350 mg/L), and ABA (5, 10 and 15 mg/L). Data was collected at seven days’ interval throughout the growth period, starting from 3 weeks after initial bending in flush 1 and after pruning in flush 2. Data obtained was analyzed using SAS version 9.4 and significant means were separated using the Least Significant Difference at ∝=0.05. The analysis of variance for flush 1 and 2 respectively, showed that CKs significantly (p<0.05) increased the number of shoots produced per plant (4.22 and 2.78 shoots), stem length (83.22 cm and 82.56 cm), leaf area (76.67 and 72.44 cm2), number of suckers (17.83 and 15.67), flush days (51.72 and 53.67 days), and chlorophyll content (72.95 and 70.77 SPADS) in cut flowers. On the other hand, the shortest stem length was recorded on plots treated with ABA (68.56 and 68.78 cm), flush days (49.06 and 50.67 days), chlorophyll content (64.74 and 65.13 SPADS) and leaf area (61 and 54.11 cm2). CaCl2 reduced incidences of bent peduncles in flushes one and two (2.07 and 1.13). To improve on the growth qualities (number of shoots produced per plant, stem length, leaf area, flush days, and chlorophyll content) the growers should consider application of cytokinin at 250 mg/L and 350 mg/L. However, application of cytokinin comes with a risk of increased number of suckers. To reduce incidences of bent peduncles, growers should always apply 750 mg/L of CaCl2 before the formation of the flower bud. To reduce the number of flush days in target of a specific market, growers can apply ABA (15 mg/L) at prebloom stage.