Ran, Y., Agricultural Research Organization, POB6, Bet Dagan 50250, Israel
Bar-Yosef, B., Agricultural Research Organization, POB6, Bet Dagan 50250, Israel
Erez, A., Agricultural Research Organization, POB6, Bet Dagan 50250, Israel

Scant information is available on the specific effect of root volume on uptake rates of water and N by trees as related to dry matter production and partitioning in the plant. The objectives of this work were to quantify these effects in peach trees and elucidate some of the mechanisms by which roots affect plant development and fruit yield. Peach trees (Prunus nersica vr. Spring Crest) were grown for 4 years in containers holding 80-, 40-, 20-, 10-, and 5-L of coarse quartz sand. All trees received an ample supply of N03-based nutrient solution, so that root volume was the predominant growth-limiting factor: Daily water and N03 inflow and outflow rates were measured. Dry matter production and partitioning between roots, trunk, branches, leaves and fruits were determined by sampling trees four times during the growth period. Root volume significantly affected total dry matter and N in trees and N partitioning among tree organs. It did not affect dry matter partitioning and content in leaves. Container volume influenced water uptake rate by trees due to its effect on root weight per plant. It had no effect, however, on water uptake characteristics per unit root weight. Nitrogen daily consumption rate increased with container volume due to the larger root weight, even though the average flux of N uptake declined with increasing root volume. The decreased flux stemmed from the fact that the fraction of l-mm diameter roots was greater in smaller containers than in larger ones. © 1992, Taylor & Francis Group, LLC. All rights reserved.