Applied Ecology and Environmental Research, cilt.16, sa.4, ss.4065-4080, 2018 (SCI-Expanded)
Citrus is a conventionally produced fruit crop in extensive agricultural areas in Mediterranean-type agroecosystems. The use of rootstocks for citrus fruits is necessary for profitable production under some limiting factors, such as climactic factors, bad soil conditions, and diseases. In addition, the use of the citrus rootstocks provides a large number of choices to growers to increase fruit quality and yield, obtain early fruiting, uniform cropping and high-density planting, avoid juvenility, and control tree size. The aim of the present study was to evaluate the effects of several citrus rootstocks on the fruit yield, quality, physiological changes in leaves and leaf mineral composition of Rio Red grapefruit. Thus, seasonal changes in the leaf chlorophyll concentration, PSII efficiency (Fv / Fm), stomatal conductance (gS), leaf temperature, leaf mineral nutrient, fruit yield and fruit quality traits of the Rio Red grapefruit variety grafted onto six commonly used rootstocks (Carrizo citrange, citremon, sour orange, Swingle citrumelo, Troyer citrange and Volkameriana) in citriculture were evaluated. The physiological responses of fully expanded young leaves to rootstocks were significantly affected by seasonal changes. Two-way ANOVA indicated significant main effects of rootstock and season and their interaction (p <= 0.05) on the leaf Chl concentration. Leaf Chl concentrations were lowest in April for all rootstocks. The PSII efficiency slightly decreased in the leaves of Rio Red grafted onto Volkameriana in February. The rootstocks significantly affected seasonal changes in the leaf stomatal conductance. The highest gS was recorded in October in the leaves of a Rio Red variety grafted onto the Volkameriana rootstock. Significant rootstock effects on leaf Ca, Mg, Mn, Zn and Cu concentrations were observed in the Rio Red variety. The highest leaf Zn concentration (ppm) was recorded in plants on Volkameriana, whereas the lowest Zn concentrations were recorded in plants on Troyer citrange. There were no significant rootstock effects on leaf N, P, K and Fe concentrations. The rootstocks significantly affected the fruit yield of the Rio Red variety in the 2013 and 2014 harvest years. The highest fruit yield was observed in Rio Red grafted onto Carrizo citrange in 2013, whereas it was highest in plants on Troyer citrange in 2014. The fruit weight (g), fruit diameter (mm), total soluble solids (%), juice content (%) and juice color (hue degrees) of Rio Red grapefruit were significantly affected by the rootstocks.