Guangdong nongye kexue (Dec 2022)
Effects of Different LED Light Qualities on Plant Growth and Flower Traits of Chrysanthemum Ping Pong
Abstract
【Objective】Due to the instability of flower color and some other growth traits of chrysanthemums growing in high temperature environment in South China, effective LED light combinations were investigated to regulate the growth and flower color of chrysanthemums in order to provide theoretical references of LED light cultivation technology for the production of chrysanthemums.【Method】Different LED light combination treatments of RBFR (the photosynthetic photon flux density PPFD ratio of red ∶ blue ∶ far-red light ≈ 10 ∶ 7 ∶ 2.5), RBUV (red ∶ blue ∶ ultraviolet light ≈ 10 ∶ 6 ∶ 0.5) and WB (white ∶ blue ≈ 10 ∶ 4.8) were performed on 35-day-old potted seedlings of commercially popular chrysanthemum cultivars of 'Pink Ping Pong'and Purple Ping Pong, the LED white light treatment was used as the CK group, the total light intensity of each group was set to be about 240 μmol·m-2s-1, and all treatments lasted for 80 days. The changes of growth trait indicators of the chrysanthemums growing from seedling to mature flowering were observed and photographed.【Result】(1) Compared with CK group, the plant heights of 80-day-treatment Pink Ping Pong and 70-day-treatment Purple Ping Pong under RBFR treatment increased by 18.3% and 27.3% respectively, the stem thicknesses increased by 14.1% and 38.1% respectively, the petiole lengths increased by 0.4% and 34.8% respectively; and the mean values of leaf length, leaf width, leaf fresh weight and leaf dry weight of the 70-day-treatment Purple Ping Pong under RBFR treatment were 18.6%, 5.8%, 25.6% and 45.5% higher than those of CK group, respectively; values of the above growth trait indicators were the highest among all treatment groups. (2) In terms of flowering trait indicators of the 70-day-treatment Ping Pong, mean values of peduncle length, peduncle diameter, petal length and petal width of the top capitulum and diameter of side capitulum of 'Pink Ping Pong'under WB treatment were the highest among all treatment groups, which were 4.5%, 2.3%, 10.9%, 17.3%, and 19.1% higher than those of CK group respectively, and the petals were of the most pink color. At the same time, Purple Ping Pong of WB group had the largest flower diameter and the petals were of the most purple color. In addition, RBFR treatment was the second most effective in improving flower traits, and peduncle length of the side capitulum of Pink Ping Pong was the longest among all treatment groups, which was 28.3% longer than that of CK group; mean values of number of buds, number of expended capitulums, peduncle length of side capitulum, petal length and petal width of the largest capitulum were also the highest among all treatment groups, which were 32.3%, 15.0%, 38.4%, 5.8% and 12.8% higher than those of CK group respectively; in addition, RBFR treatment also resulted in the early opening of capitulums of Chrysanthemum 'Ping Pong'. (3) The growth traits of Chrysanthemum Ping Pong under RBUV treatment were not significantly different from those of CK group, but the number of leaves and the SPAD value of leaves increased, and the ratio of leaf dry weight were significantly increased, however, the decrease of Fv/Fm value decreased was larger than that of other groups and the flower quality decreased obviously.【Conclusion】It can be seen that RBFR treatment can significantly promote the vegetative growth and peduncle length of the side capitulum of Chrysanthemum Ping Pong, and result in the early opening of the capitulums. Meanwhile, WB treatment significantly improves the flower quality. Therefore, the two LED light combinations can provide a reference for people to use artificial lights to improve the planting quality of chrysanthemums in the future.
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