The effect of soil water on root production of peach trees in summer

Abstract

The effect of soil water supply on peach root production in summer was studied in the Goulburn Valley area of northern Victoria. Under commercial irrigation practice roots do not grow in summer. Field experiments showed that when the soil was kept moist by frequent irrigation (every 3–4 days), the concentration of roots in the surface soil nearly doubled in a single season. Furthermore, observation through glass plates showed that this enhanced root growth occurred throughout summer. When roots were kept inactive in dry soil until midsummer and thereafter irrigated frequently, they immediately responded and grew rapidly. The increased root growth did not impair fruit production. In a glasshouse experiment, with glass-fronted chambers, a relationship between root elongation, root concentration and the drying rate of the soil was found.

Each experiment supported the hypothesis that soil drying rate determines the growth of roots in the surface soil. Where there was a high concentration of roots, a low irrigation frequency, and high transpiration, the rate of soil drying was rapid and roots grew slowly.

It is suggested that manipulation of root growth by regulation of soil water supply may be an important method of studying root-top interactions.