Comparison of root anatomy and xylem vessel structure in rain-fed and supplementary irrigated ‘Yaghooti-Syah Shiraz’ grapevine (Vitis vinifera L.)

Abstract

Changes in environmental conditions may lead to modifications in structural development of plant root. Effects of supplementary irrigation and soil depths (0–90 cm) on anatomical changes in xylem were investigated in rain-fed Vitis vinifera L. cv. Yaghooti-Syah Shiraz. Irrigated and control roots were prepared according to routine histological procedure. Light microscopic observations revealed the structural features of drought tolerant control roots and their changes after the treatment. Irrigated roots were characterized by the absence of starch grains in parenchyma cells, uniformity of parenchymatous pith cells, and a decrease in periderm thickness. Morphometric investigation of xylem showed that irrigated and deep roots had larger mean and maximum vessel diameter and fewer vessel number than rain-fed and shallow roots, at every soil depth of every treatment. Secondary xylem vessel diameter and number were more affected by irrigation and soil depths than metaxylem. Grape roots responded to supplementary irrigation and increasing soil depth by reducing protective and supporting tissues and increasing vessel diameter.