Light quality plays a significant role in regulating the growth, development and physiological metabolism of plant seedlings. Generally, red light is beneficial to the elongation of seedling stems and the accumulation of dry matter, while blue light can promote the synthesis of protein, increase the activity of antioxidant enzymes, etc., and red blue combined light is more conducive to seedling breeding. Su Nana et al μ Under the light intensity of mal/m2 · s, compared with the control white light, red light and blue light significantly increased the leaf area, plant height and healthy seedling index of cucumber, while yellow light and green light significantly decreased the above indicators, playing an inhibitory role.
Deram et al μ Mol/㎡· s, medium 115 μ Mol/㎡· s and 100 lower μ Mol/mol/㎡· 9) and red blue light (661mm) and (449nm) light quality ratio (5:1, 10:1 and 19:1) The control treatment included 100% HPS, 100% red LED irradiation on the canopy, 100% red light irradiation under the canopy, 50% LED and 50% HPS mixed light sources, and control (no complementary light).
Except for fruit, the highest biomass occurred in the 19:1 treatment, with the increase of light intensity and yield. The highest fruit yield was 50% LED and 50% HPS treatments, followed by 5:1 and 19:1 treatments. The performance of red blue light at 5:1 is good. LED is superior to HPS in promoting fruit production, and its mixing effect with HPS is better.
Wang Hong et al. (2010) studied the effects of different light qualities, such as white light (W), purple light (P), blue light (B), green light (G), yellow light (Y) and red light (R), on the contents of chlorophyll, soluble protein and malondialdehyde (MDA) in leaves, and the activities and gene expression of antioxidant enzymes, such as CAT, G-POD and APX, using cucumber as materials, to clarify the role and mechanism of different light qualities on cucumber leaf senescence. Purple light and blue light induced the expression and activity of antioxidant enzymes, delayed the decline of chlorophyll and soluble protein content, and kept the content of MDA at a relatively low level, thus delaying plant senescence. Green light, yellow light and red light inhibited the activity of antioxidant enzymes, which led to the continuous decrease of chlorophyll and soluble protein content and the continuous increase of MDA content in cucumber plants, and accelerated the aging process of plants. Purple light and blue light can maintain a higher level of antioxidant enzymes in leaves, thus delaying plant senescence.
Light also regulates many enzyme activities and stomatal opening in the process of carbon assimilation, affecting plant growth, metabolism and material transport. Light quality and intensity can regulate the formation of different types of chlorophyll protein complexes in photosynthesis and the electron transfer between photosystem domains (Kim et al., 1993; Patil et al., 2001). The results showed that blue light could reduce the level of IAA in plants and inhibit their growth, while red light could promote the elongation of cotyledons and inhibit the excessive growth of stems; Blue light can promote the synthesis of chloroplast development genes in tobacco leaves, but can be reversed by red light (Richater and Wessel, 1985). Light has a greater impact on plant nutrient content (Kopsell and Kopsell, 2008; Balibrea et al., 2008).
Photoperiod
Photoperiod regulation is to solve the problem of insufficient light intensity and light time caused by geographical location, weather conditions and seasonal changes of photophiles in protected cultivation. Photoperiod regulation can shorten the culture cycle, regulate flowering time, and segment photoperiod management can achieve different culture objectives. Photoperiod is the alternation of the length of designated period and dark period. Plants sense the change of photoperiod through photoreceptors, and regulate plant physiological characteristics and flowering response. Generally, prolonging the photoperiod of plant seedlings can promote their growth and physiological metabolism. Chen Min and Li Haiyun (2010) found that prolonging light time increased plant height, stem diameter, growth rate, chlorophyll content and antioxidant enzyme activity of eggplant.
Plant seedling breeding and its light environment regulation（二）
Light quality
Light quality plays a significant role in regulating the growth, development and physiological metabolism of plant seedlings. Generally, red light is beneficial to the elongation of seedling stems and the accumulation of dry matter, while blue light can promote the synthesis of protein, increase the activity of antioxidant enzymes, etc., and red blue combined light is more conducive to seedling breeding. Su Nana et al μ Under the light intensity of mal/m2 · s, compared with the control white light, red light and blue light significantly increased the leaf area, plant height and healthy seedling index of cucumber, while yellow light and green light significantly decreased the above indicators, playing an inhibitory role.
Deram et al μ Mol/㎡· s, medium 115 μ Mol/㎡· s and 100 lower μ Mol/mol/㎡· 9) and red blue light (661mm) and (449nm) light quality ratio (5:1, 10:1 and 19:1) The control treatment included 100% HPS, 100% red LED irradiation on the canopy, 100% red light irradiation under the canopy, 50% LED and 50% HPS mixed light sources, and control (no complementary light).
Except for fruit, the highest biomass occurred in the 19:1 treatment, with the increase of light intensity and yield. The highest fruit yield was 50% LED and 50% HPS treatments, followed by 5:1 and 19:1 treatments. The performance of red blue light at 5:1 is good. LED is superior to HPS in promoting fruit production, and its mixing effect with HPS is better.
Wang Hong et al. (2010) studied the effects of different light qualities, such as white light (W), purple light (P), blue light (B), green light (G), yellow light (Y) and red light (R), on the contents of chlorophyll, soluble protein and malondialdehyde (MDA) in leaves, and the activities and gene expression of antioxidant enzymes, such as CAT, G-POD and APX, using cucumber as materials, to clarify the role and mechanism of different light qualities on cucumber leaf senescence. Purple light and blue light induced the expression and activity of antioxidant enzymes, delayed the decline of chlorophyll and soluble protein content, and kept the content of MDA at a relatively low level, thus delaying plant senescence. Green light, yellow light and red light inhibited the activity of antioxidant enzymes, which led to the continuous decrease of chlorophyll and soluble protein content and the continuous increase of MDA content in cucumber plants, and accelerated the aging process of plants. Purple light and blue light can maintain a higher level of antioxidant enzymes in leaves, thus delaying plant senescence.
Light also regulates many enzyme activities and stomatal opening in the process of carbon assimilation, affecting plant growth, metabolism and material transport. Light quality and intensity can regulate the formation of different types of chlorophyll protein complexes in photosynthesis and the electron transfer between photosystem domains (Kim et al., 1993; Patil et al., 2001). The results showed that blue light could reduce the level of IAA in plants and inhibit their growth, while red light could promote the elongation of cotyledons and inhibit the excessive growth of stems; Blue light can promote the synthesis of chloroplast development genes in tobacco leaves, but can be reversed by red light (Richater and Wessel, 1985). Light has a greater impact on plant nutrient content (Kopsell and Kopsell, 2008; Balibrea et al., 2008).
Photoperiod
Photoperiod regulation is to solve the problem of insufficient light intensity and light time caused by geographical location, weather conditions and seasonal changes of photophiles in protected cultivation. Photoperiod regulation can shorten the culture cycle, regulate flowering time, and segment photoperiod management can achieve different culture objectives. Photoperiod is the alternation of the length of designated period and dark period. Plants sense the change of photoperiod through photoreceptors, and regulate plant physiological characteristics and flowering response. Generally, prolonging the photoperiod of plant seedlings can promote their growth and physiological metabolism. Chen Min and Li Haiyun (2010) found that prolonging light time increased plant height, stem diameter, growth rate, chlorophyll content and antioxidant enzyme activity of eggplant.