ROOT DEVELOPMENT PATTERNS IN FIELD-GROWN PEACH-TREES

The objective was to determine the interrelationship between root grow th and plant available soil water (PAW) for young, nonbearing, and mat ure fruiting peach trees (Prunus persica L. Batsch) over 7 years. Root growth observed with minirhizotrons indicated that young, nonbearing trees developed new white roots throughout the growing season. The pat tern of new white root growth became bimodal when the trees fruited. W hite root production in mature trees appeared in March, preceding budb reak, ceased in June, resumed following fruit removal in August, and p ersisted through January. The appearance of white roots was inversely related to the presence of fruit and was not correlated to PAW levels in the 0 to 90 cm depth. The lack of root growth response to PAW level s was attributed to a root system that penetrated the soil to depths b eyond our zone of sampling. Circumstantial evidence suggests that deep roots help maintain the surface root system when the surface soil dri es.