عنوان مقاله [English]
Background and Objectives
According to the results, plants behave differently under different lighting levels. Recent studies have demonstrated that proper light adjustments are critical for production of bedding plant transplant production. The production of transplants under high light density and proper control of environmental condition can increase transplant quality compared to traditional greenhouse production conditions which accordingly affects their growth and yield after transplantation.
Materials and methods:
In order to compare the effect of 60±5 and 120±5 µmol.m-2.s-1 LEDs in the growth chamber (a combination of white+ blue+ red LEDs equally) with sunlight during winter and spring cultivation at 9.6±5 and 14±5 µmol.m-2.d-1 DLI, respectively, a completely randomized design established with 10 replications. the morphological and physiological traits of Pelargonium (Pelargonium hortorum 'Maverik Star'), Solenostemon (Solenostemon escutellariodes 'Wizard Scarlet') and Petunia (Petunia × hybrida 'Scarleti') transplants evaluated during the experiment. Transplants were sampled to evaluate morphological traits such as shoot fresh and dry weight, root fresh and dry weight, leaf area, plant height and root height. Shoots and roots were dried in a drying oven at 72°C for 24 hours to determine dry weight. Chlorophyll efficiency (Fv/Fm), anthocyanin and carotenoid contents also were measured during the experiment.
After 8 weeks, leaf area, root length, shoot and root fresh and dry weight, leaf number, leaf surface temperature, chlorophyll, carotenoid and photosynthetic efficiency were measured in transplants. Solenostemon and geranium transplants were also evaluated for height, internode length, stem diameter and leaf anthocyanin content. Results showed that leaf area traits, leaf number, internode length, stem diameter, photosynthetic efficiency, shoot and root fresh and dry weight in geranium and Solenostemon and chlorophyll content and leaf number in Petunia at 60±5 µmol.m-2.s-1 was significantly higher than the other treatments. The leaf surface temperature of transplants in both spring and winter cultivation treatments was higher than that of LEDs. The results showed that there was a significant difference between the LED and sun light treatments and the LED light resulted in more compare to the sun light.
Transplants grown under identical proportion of white, blue and red LED light had desirable morphological and physiological characteristics which led to better morphological features. According to the results, the use of alternative or complementary light for the production of high quality seedlings is beneficial. It is especially recommended in winter cultivation for the production of proper transplants of Geranium, Nettle painted and Petunia bedding plants.