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

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 mate-rials 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 under-lying blueberry resistance to high soil pH.

Automated summary

This study investigated the effects of different soil pH levels on the growth and development of blueberry cultivars. It was found that high soil pH hindered green color development in blueberry leaves and inhibited plant growth. However, different cultivars showed tolerance to high soil pH, with a threshold of pH 6.5. Antioxidant enzyme activities and leaf SPAD values were closely related to blueberry growth and dry matter accumulation, and served as important indicators for assessing blueberry adaptation to high soil pH environments.