Analysis of moon orchid response to osmotic stress through measurement of chlorophyll content and tolerance index

Orchidaceae is a group of flowering plants with a very high level of diversity, comprising more than 28,000 species spread across the globe. One of the most well-known species is the moon orchid (Phalaenopsis amabilis). In cultivation practices, drought is a limiting factor that can inhibit plant growth. One strategy considered effective in overcoming this condition is the use of varieties that are tolerant to drought stress. This study aims to: (1) identify the concentration of PEG 6000 that still supports the growth of P. amabilis in vivo under drought stress, and (2) characterize the response of plants treated with PEG 6000, which includes the stress tolerance index and the content of chlorophyll a, chlorophyll b, and total chlorophyll. Data were analyzed using ANOVA and followed by the BNJ test at a 5% level. The results showed that a PEG 6000 concentration of 40% was still tolerable by P. amabilis. Increasing PEG 6000 concentration tended to decrease chlorophyll a, chlorophyll b, and total chlorophyll content, while the tolerance index at 40% treatment showed that the plants were still able to survive drought stress.