Growth and physiological characteristics of four blueberry cultivars under different high soil pH treatments

Abstract

Blueberry is economically important small pulp shrub that prefers to grow in acidic soil, and soil pH is an important factor affecting blueberry growth and development. In this study, one-year-old seedlings of four blueberry cultivars, namely, ‘Primadonna’, ‘Anna’, ‘Baldwin’ and ‘Bluegold’, were used as experimental materials to study the changes in physiological and biochemical indexes, such as growth potential, osmoregulatory substance levels, antioxidant enzyme activities and antioxidant capacity, of blueberry cultivars under soil pH values of 5.5 (CK), 6.0 (T1), 6.5 (T2), 7.0 (T3) and 7.5 (T4), and the relationships between various indexes were analyzed. The overall results showed that soil pH stress led to deficiency in green color development in blueberry leaves and inhibited plant growth in terms of the height, main basal diameter and biomass (dry weight). Through determination of the blueberry growth phenotype and growth indexes, it was found that the ‘Primadonna’, ‘Anna’, ‘Baldwin’ and ‘Bluegold’ cultivars had a certain tolerance to high soil pH, and the tolerance threshold was pH 6.5. Correlation and principal component analyses showed that the MDA content, SOD and CAT antioxidant enzyme activities, DPPH free radical scavenging ability, and SPAD values of blueberry leaves were closely related to the growth and dry matter accumulation of blueberry under high soil pH environments; these values were important reference indexes for assessing the adaptation of blueberry to a high soil pH environment. Our study provides a reference for soil management for blueberry cultivation and for research on the mechanism underlying blueberry resistance to high soil pH. • Soil pH 6.5 was the threshold for growth of the four blueberry cultivars. • High soil pH destroys blueberry photosynthesis and antioxidant system. • SPAD, DPPH, CAT, SOD were positively correlated with blueberry growth. • MDA was negatively correlated with blueberry growth and dry matter accumulation.