Substrate composition affects growth and physiological parameters of blueberry

There is currently a growing interest in soilless substrates for blueberry cultivation. Identifying optimal substrate for the growth and development of the crop, and understanding the physiological response of blueberries is not only essential to determine the appropriate growing conditions, but also to improve the quality of the fruit. In this study, we evaluated the development and physiological response, and quality of blueberry plant fruits grown on two types of substrate. For this, the “Legacy” variety blueberry plants (Vaccinium. corymbosum, L) were grown in substrate composed of coconut fiber and peat (3:1) (substrate 1) and in substrate only composed of coconut fiber (substrate 2). The plants were kept in a greenhouse with controlled humidity and temperature conditions, and were drip-irrigated with modified Steiner solution. The blueberry plants grown in substrate 2, had a higher growth and yield compared to substrate 1. The analysis of nutrients in the substrate showed a higher concentration of nutrients in substrate 1, but in a post-transplant percolate analysis, substrate 2 was found to have a higher nutrient retention. Also, the stomatal density and the stomatal conductance show significant and differences and opposite response with the treatments, finding the highest number of stomata per mm² in the plants grown with substrate 2, and a higher stomatal conductance with substrate 1. The plants with substrate 2 showed a better fruiting potential and reached a larger fruit diameter. The results indicate a higher suitability of substrate 2 for growing blueberry, but not only due to the values obtained, but for the potential better response against any environmental change that could alter water relations.