Effect of pH, light intensity, and fertilizers on acclimatization of endangered rooted plantlets Malus niedzwetzkyana for restoration in nature

Abstract

Malus niedzwetzkyana is an endemic, endangered, and valuable plant species. To conservation Malus niedzwetzkyana in nature, it is necessary to obtain planting material with a high survival rate. Selection of optimal pH, light intensity, and fertilizers is necessary to obtain high survival rate during the adaptation period of microshoots after micropropagation and in vitro culture. For optimization of adaptation condition of in vitro rooted microshoots of M. niedzwetzkyana were used. This work investigated the effect of pH level, light intensity, and fertilizers on the growth parameters of micropropogated microshoots of M. niedzwetzkyana. To select the optimal pH and substrate four types of substrates were studied: neutral peat, acid peat, neutral soil, and acidic soil. In addition, as the artificial light source two lighting conditions were studied: LED phyto tapes (4680 lx) and fluorescent phytolamps (7410 lx). In result, highest survival rate was obtained in treatments using peat or soil at neutral pH and 7410 lx light intensity. Additionally, to acclimatize the plantlets in a greenhouse the fertilizers effects were studied: potassium nitrate, monoammonium phosphate, Special crystallon, ammonium nitrate. Thus, irrigation with the Special Crystallon was an effective treatment for seedlings and substantial growth was observed in the aboveground and underground parts of the plants post transfer to greenhouse conditions. After 4 months the average height of seedlings, the number of shoots, and the crown diameter were 114.42 cm, 25.67, and 61.83 cm, respectively with 90% survival rate of planting material after three years under natural conditions.