Effects of nitrosigine on Malus hupehensis seedling growth and apple fruit quality

【Objective】In order to explore the effects of nitrosigine applied to plants as a fertilizer on the plant growth and fruit quality, the experiment was undertaken so as to provide a theoretical basis for the selection of new silicon fertilizer in the agricultural production.【Methods】The experiment was conducted in 2023 at the National Key Laboratory of Wheat Improvement, Shandong Agricultural University (Cultivation environment temperature of Malus hupehensis Rehd. seedlings was 25 ℃; the photoperiod for plant growth was 14 hours light and 10 hours darkness) and the Modern Agricultural Science and Technology Demonstration Park of Nanma Town, Yiyuan county, Zibo City, Shandong province (117° 54'-118°31', 35°55'-36°23', the region belongs to a warm temperate continental monsoon climate) respectively. M. hupehensis Rehd. seedlings as well as 6-year-old Gala/M9 and Fuji/M9 apple trees wereused as experimental materials. Four kinds of substances (water, K2SiO3, Arginine and Nitrosigine) and two different concentrations (2 mmol·L-1 and 6 mmol·L-1 ) were applied to M. hupehensis Rehd. seedlings, respectively. After 28 days of treatments, various indicators, including plant height, above-ground and underground biomass, leaf growth, net photosynthetic rate, silicon content and other seedling growth related indexes were determined. Gala/M9 and Fuji/M9 apple trees were sprayed with water and 30 mmol·L-1 Nitrosigine respectively. The sprayed treatments were carried out from the beginning of fullblossom period to the end of fruit ripening, and the samples were treated once a month. After ripening, various indicators, including fruit mass, soluble solid content, soluble sugar content, hardness, pectin content and other fruit quality indexes were determined.【Results】The results showed that 2 mmol·L- 1 and 6 mmol · L- 1 K2SiO3, Arginine and Nitrosigine treatments could significantly promote the growth of M. hupehensis Rehd. seedlings compared with control treatment, and Nitrosigine treatment could improve the seedling growth better than K2SiO3 and Arginine treatment. Nitrosigine of 2 mmol·L-1 and 6 mmol · L- 1 significantly increased the plant height of M. hupehensis Rehd. seedlings by 60.65% and 62.28% compared with control, respectively, and Nitrosigine could make the seedlings grow faster. The stem diameter of M. hupehensis Rehd. seedlings treated with 2 mmol· L- 1 and 6 mmol· L- 1 Nitrosigine significantly increased by 27.96% and 29.55% compared with control, respectively. The above ground fresh mass of M. hupehensis Rehd. seedlings treated with 2 mmol·L-1 and 6 mmol·L-1 Nitrosigine significantly increased by 146.76% and 167.72% respectively compared with control. The leaf chlorophyll a and chlorophyll b contents of M. hupehensis Rehd. seedlings with 2 mmol·L-1 Nitrosigine treated were significantly higher than those of control by 78.86% and 91.81%, respectively. The leaf chlorophyll a and chlorophyll b contents of M. hupehensis Rehd. seedlings with 6 mmol·L-1 Nitrosigine treated were significantly higher than those of control by 76.19% and 91.13%, respectively. The net photosynthetic rate, transpiration rate and stomatal conductance of seedlings treated with 6 mmol·L-1 Nitrosigine were significantly higher than control by 497.0%, 89.20% and 136.34%, respectively. In conclusion, on the one hand, Nitrosigine treatment could significantly increase the leaf silicon content and the chlorophyll content of M. hupehensis Rehd. seedlings, and also enhance their net photosynthetic rate, which promoted photosynthesis of M. hupehensis Rehd. seedlings. On the other hand, Nitrosigine treatment could increase the leaf biomass and promote leaf growth; It could significantly increase plant height, stem diameter, above-ground dry and fresh mass of M. hupehensis Rehd. seedlings, and promote plant vegetative growth. The results of seedling tests showed that Nitrosigine can significantly promote the growth of M. hupehensis Rehd. seedlings compared with K2SiO3 and Arginine. In order to verify its effect on apple fruits, we referred to the optimal concentration of K2SiO3 sprayed on Fuji apple trees. Nitrosigine was sprayed on 6-year-old Gala/M9 and Fuji/M9 apple trees. Nitrosigine can significantly increase the anthocyanin content of Gala and Fuji apples by 60.62% and 6.82%, which could promote fruit coloring. The soluble solid contents in Gala and Fuji fruits significantly increased by 3.66% and 5.82%; The total amount of pectin and flesh hardness of apples significantly increased. The silicon content in peel and pulp of Gala apples significantly increased by 103.32% and 167.88%, respectively, the silicon content in peel and pulp of Fuji fruits significantly increased by 95.94% and 172.49%, respectively.【Conclusion】Nitrosigine treatments could significantly increase the silicon content and promote the growth of M. hupehensis Rehd. seedlings. It can also improve the appearance and internal quality of Gala and Fuji fruits. Among them, the best concentration for M. hupehensis Rehd. seedlings was 6 mmol· L- 1 , and if excessive high dosage application may cause stress to the seedlings.