Vegetative Growth Distribution During Water Deficits in Vitis vinifera L

Abstract

The expansion of plant organs is inhibited by water deficits but the effect of ontogeny on growth sensitivity is not known. Therefore, growth responses of shoot organs (internodes, leaves, tendrils) of Vitis vinifera L. cv. White Riesling to developing water deficit were investigated under controlled environmental conditions. Growth of organs at a node position was asynchronous, with internode growth being more restricted than leaf and tendril growth in time (duration of growth) and space (number of node positions at which growth occurred).

The timing of initial growth inhibition and final growth cessation caused by soil water deficits was identical in internodes, leaves, and tendrils. The degree of growth inhibition at low water potential was similar among organs, whether linear or volume changes were considered and whether the most rapidly expanding organs or organs of similar developmental stage were compared. In addition, the relative partitioning of growth among internodes, leaves, and tendrils along single shoots was unaltered when growth was inhibited by water deficits. Growth of each organ was inhibited initially at soil water potential of -0.065 MPa and ceased completely at -0.54 MPa. Therefore, it was concluded that the sensitivity of growth to water deficits did not differ among shoot organs.

The region along the shoot in which organs expanded was reduced during water deficits. Similarly, the regions within organs in which growth occurred diminished as water deficits developed. Although growth was inhibited in all tissues, inhibition was complete in older tissues when some growth was maintained in younger tissues. Therefore, it was concluded that sensitivity of growth to water deficits increased with ontogeny.