Yield and quality of cut roses of Jumelia variety grown in greenhouse

Rose is one of the most well-known cut ornamental flowers worldwide, and the production of roses in commercial greenhouses is of great importance. This flower is a light-loving plant among ornamental flowers, and providing appropriate light during the growing period is one of the important measures in increasing the yield and quality of greenhouse roses on low-light and cloudy days. Increasing the available light of roses in greenhouse cultivations is done using supplementary light sources. In recent years, the use of new supplementary lights as an alternative to old light sources in improving the growth and development conditions of ornamental plants has received much attention. For this purpose, the present study aimed to investigate the effect of a supplementary light source on the morphological and physiological indices of roses of the Jumelia cultivar. New supplemental lights including hybrid LED light were compared with conventional and old light sources such as metal vapor and high-pressure sodium to determine the optimal supplemental light source for hydroponic production of rose cuttings of Jumelia cultivar during the cold season, and natural sunlight was considered as a control.

Materials and Methods

This experiment was conducted in a completely randomized design with four light treatment groups including metal vapor supplemental lights, high-pressure sodium, hybrid light-emitting diodes, and control (natural sunlight without supplemental lighting) in three replications, and each replication included four rose plants. The experiment was conducted in a specialized rose greenhouse located in the research greenhouse of the Faculty of Agriculture, Isfahan University of Technology, in 1400-1399. In this study, morphological and physiological traits including bud length, flower stem diameter, calyx diameter, number of leaves at flowering time, number of flowers, amount of chlorophyll a and b in leaves, relative leaf water content, leaf protein and chlorophyll fluorescence in leaves of rose cultivar Jumelia were measured.

Findings

Based on the results obtained, the effect of supplementary light treatments on morphological and physiological traits rose cut branches of the Jumelia cultivar were significant. Compared to the control treatment, the combined light-emitting diode treatment had the greatest effect on the indices of bud length, flower stem diameter, and flower calyx diameter; a similar result was obtained in increasing the number of leaves and flower branches. Also, the accumulation of leaf photosynthetic pigments, including chlorophylls, showed the greatest increase in the combined light-emitting diode treatment. Growth light-emitting diodes were able to significantly increase the relative water content of the leaf compared to other treatments. The amount of protein measured in the leaf tissue of rose treated with combined light-emitting diodes was higher than other treatments. By examining the chlorophyll fluorescence index, it was determined that the light-emitting diodes provided more suitable growth conditions for the growth of rose plants. Among the treatments studied, the highest quantity and quality of rose cuttings of the Jumelia cultivar were produced by combined light-emitting diode treatments compared to other supplementary light treatments and the control treatment.

Conclusion

Given the favorable effects of combined light-emitting diode treatments on the quantitative and qualitative characteristics of rose cultivar Jumelia and considering higher energy efficiency and economic savings over a longer period of time in greenhouse cultivation, the use of combined light-emitting diodes in supplementary lighting of intensive cultivation is a priority. Hybrid diode supplemental lights are recommended due to their significant superiority over the control and the positive role they play in improving the growth and development process of rose Jumelia; hybrid diode supplemental light is also recommended as an alternative to metal vapor and high-pressure sodium supplemental lights.