Comparison Effects of Cymbidium mosaic virus (CymMV) Infected on Growth, Yield and Quality of Flowers for Dendrobium Orchids Easakul (BOM)

Abstract

Dendrobium orchids hybrids for fresh cut flower when propagated by division or tissue culture without Cymbidium mosaic virus (CymMV) detection before propagation have been found to be infected at a high rate of viral infection and epidemic. This research aimed to examine the effects of CymMV infection on growth, flower quantity, and flower quality of the orchid genus Dendrobium Sonia Easakul (BOM). The experiment was arranged in a completely randomized design, comparing the results between virus-free (Control) and CymMV-infected plants. The virus-free and CymMV-infected orchids were selected by the POCy kit. A piece of bud fragments for virus-free and CymMV-infected orchids were used to induce the generation of protocorm-like bodies (PLBs) and develop into plantlets as a 3.5–inch potted plant. After planting at 3 and 6 months, the results showed that pseudobulbs height, diameter of pseudobulbs, and number of inflorescences per clump of the virus-free plants showed better growth than those CymMV-infected plants at both ages with a statistically significant difference (P < 0.01) while the number of trunks per clump of both plants was significantly different at 6 months old only (P < 0.01). When planted as cut flowers by using coconut husks as planting material under the semi-closed environmental controlled greenhouse and 50% shade netting greenhouse without environmental control found that at 20 months of age, pseudobulbs height, diameter of pseudobulbs, number of inflorescences per clump and number of inflorescences per trunk of orchids from virus-free planted in both types of greenhouses showed better growth performance than the CymMV-infected orchid with highly statistically significant difference (P < 0.01). Whereas the number of trunks per clump of virus-free orchid was higher than the CymMV-infected orchid when only planted under the 50% shade netting greenhouse without environmental control (P < 0.01). For the quality and size of orchid flowers at 9 and 15 months of age, it was found that the length of inflorescence, number of flowers per inflorescence, and flower size of orchids from free-virus plants were statistically significantly higher than CymMV-infected plants. The results of the vase life of orchid flowers tested in water at room temperature found that the flowers of free-virus orchids had a vase life of 14 days while the flowers of CymMV-infected orchids had a vase life of 21 days. These results might be due to the virus-free orchid have higher dehydration and loss of maturity, resulting in rapid deterioration. Therefore, virus-free cultivars should be selected for propagation to increase yields and quality.