Root zone temperature influences the growth, dry mass partitioning and leaf morphology of actively growing and bud-break plants of the peach rootstock, green leaf nemaguard.

摘要

Root zone temperature (RZT) may significantly affect plant growth and yield in stone fruit. To investigate the effects of RZT, actively growing plants and those emerging from dormancy (bud-break plants) of the rootstock, Green Leaf Nemaguard, were grown at constant (5, 15 and 20 degrees C) or diurnally variable (26/15 degrees C) RZTs. For plants whose roots were kept at a constant RZT, a positive correlation between the RZT and growth, including final leaf area, leaf numbers and daily rates of leaf expansion was found for both sets of plants. However, both actively growing and bud-break plants exposed to variable RZTs were smaller with respect to overall growth and in leaf morphology parameters than plants exposed to constant RZTs of 20 degrees C: this is despite mean daily RZT for both treatments being similar. There were differences between bud-break and actively growing plants in the distribution of the dry mass among roots, stems and leaves in response to RZT. In both actively growing and bud-break plants, the root mass ratio (% root dry mass/total plant dry mass) and leaf mass ratio were greatest at 20 degrees C and 5 degrees C RZTs, respectively. In actively growing plants, the stem mass ratio was greatest at 5 degrees C while in bud-break plants stem mass ratio was lowest at this RZT. These trials demonstrated that RZT, independently of air temperatures and light levels, influenced growth and partitioning of dry matter among roots, stems and leaves at different phenological stages in peaches. These results illustrate the importance of spring RZTs on growth and leaf development in plants exiting dormancy and reinforce the need to incorporate RZT into development models for peaches..