Response of Ascocenda orchid to growth regulator and micronutrients

Abstract

A study entitled ‘Response of Ascocenda orchid to growth regulator and micronutrients’ was carried out at Department of Floriculture and Landscaping, College of Horticulture Vellanikkara, from May 2018 to May 2019. Ascocenda is a monopodial, epiphytic, bigeneric hybrid, which is mainly grown as pot plant in hanging baskets using bricks, charcoal, coconut husk pieces etc. as growing media. The objective of the study was to evaluate the influence of foliar application of different micronutrient treatments on growth and yield of Ascocenda orchid. The experiment was conducted with eleven treatments viz., 0.01% zinc + 150 ppm benzyl adenine + PoP (T1), 0.025% zinc + 150 ppm benzyl adenine + PoP (T2), 0.01% manganese + 150 ppm benzyl adenine + PoP (T3), 0.025% manganese + 150 ppm benzyl adenine + PoP (T4), 0.01% boron + 150 ppm benzyl adenine + PoP (T5), 0.025% boron + 150 ppm benzyl adenine + PoP (T6), 0.01% iron + 150 ppm benzyl adenine + PoP (T7), 0.025% iron + 150 ppm benzyl adenine + PoP (T8), 0.01% molybdenum + 150 ppm benzyl adenine + PoP (T9), 0.025% molybdenum + 150 ppm benzyl adenine + PoP (T10), 150 ppm benzyl adenine + PoP (T11 – control). Three month old tissue cultured plants of Ascocenda var. Big Suksamran were used for the study. The micronutrients were applied at fortnightly intervals and benzyl adenine was applied at monthly intervals. Application of NPK (3:1:1) weekly twice @ 0.2% and cow dung slurry (1:5) at monthly intervals was given to all treatments as per PoP recommendation of KAU. Observations were taken at monthly intervals. The results indicated that foliar application of 0.025% manganese along with 150 ppm BA and recommended dose of NPK (T4) was best for improving plant height. The maximum plant height obtained at 12MAP was 8.86 cm. This was followed by T5 (8.81 cm) and T3 (8.63 cm) which were statistically on par with T4. The maximum shoot diameter was observed in T5 (10.20 mm) at 12 MAP which was on par with T4 and T3 (9.96 mm and 9.84 mm respectively). The treatment T3 was superior in terms of leaf characters like leaf length and leaf area up to 7 MAP and thereafter these parameters were highest in treatment T5. However, there was no significant difference between T5 and T3 in terms of leaf length at 12 MAP (16.70 cm and 16.48 cm respectively). The highest leaf area at 12 MAP was observed in T5 (23.17 cm2) followed by T3 (22.73 cm2). Number of leaves and leaf breadth were found highest with the

application of 0.01% boron along with 150 ppm BA and recommended dose of NPK. A maximum of 13.69 leaves were observed in T5 at 12MAP. The maximum leaf breadth observed in T5 after 12 months of planting was 1.52 cm, which was closely followed by T3 and T4 (1.51 cm each), and no significant difference between these three treatments could be noticed. Regarding interval of leaf production, only 4 treatments (T3, T4, T5, and T11) could produce the highest number of eight leaves, within a period of 386 days. Among these, T4 took the shortest period of 337.45 days to produce the 8th leaf. T10 produced only five leaves within a period of 386 days. Among the root parameters, highest root length was observed in T3 (0.01% manganese + POP + 150 ppm BA) at 12 MAP (26.59 cm) whereas the treatment T4 (0.025% Mn + PoP + 150 ppm BA) was superior in terms of number of roots and root diameter. The best treatment with respect to number of roots varied during initial months, even though, from 6 MAP onwards, highest number of roots was observed in T4 with a value of 10.28 at 12 MAP. In the case of root diameter, a highest of 2.91 mm was recorded in T4 at 12 MAP, which was on par with T8 (2.86 mm), T3 (2.84 mm) and T5 (2.82 mm). Among the eleven treatments, T3 (Mn 0.01% + PoP + 150ppm BA), T4 (Mn 0.025% + PoP + 150ppm BA), and T5 (B 0.01% + PoP + 150ppm BA)were found to be best for improving the vegetative characters of Ascocenda orchid, while application of Mo @ 0.025% (T10) at fortnightly intervals was inhibitory to the plants in terms of all the vegetative characters studied. The objective of studying the floral and postharvest characters could not be achieved since the plant did not bloom within the period of study.