Fruit production and leaf net photosynthesis dynamics in Berberis microphylla G. Forst: the role of light and fertilization

Abstract

Berberis microphylla is an evergreen, fruit-producing shrub whose black—blue berriesare considered as non-timber products from the Patagonian forest, which areextremely rich in phenolic compounds. This study evaluated changes in fruit productionand leaf net photosynthesis rate (NPR) of B. microphylla plants growing under differentirradiances (low 24%, medium 57%, and high 100% of the natural irradiance) andfertilization levels (L0=0.00 g, L1=3.36 g, and L2=6.72 g per plant) over two growingseasons. Fruiting shoot production, fruit yield and fruit and seed growth in B.microphylla increased between 1.1 and 1.6 times when comparing plants grown underhigh light intensity to those grown under medium light intensity. Additionally, the doublesigmoid curve in fruit growth under high light intensity showed two periods of rapidgrowth separated by a slower growth phase, with the slower phase being lesspronounced under medium light intensity. Fruiting shoot production, fruit yield and fruitand seed growth in B. microphylla increased by 1.3 to 7.0 times in plants fertilized withL1 and L2 compared to those with L0. The interaction between fertilization and lightintensity in the NPR was significant; therefore, the effectiveness of fertilization dependson the light intensity, with the NPR higher with high light intensity and fertilization L1-L2. Principal components PC1 and PC2 are explained by similar variables, while PC3is primarily explained by NPR and fruit color. These findings are critical for establishingeffective management practices for this shrub in production orchards, such as optimalplanting distances and pruning schemes. Additionally, understanding the role ofsupplementary nutrients is crucial for developing targeted fertilization plans.