The response of 'Catherine' cultivar peach trees grafted on sixteen rootstocks under four irrigation levels

The growth parameters, trunk cross-sectional area (cm 2), canopy size (M) and yield (kg/tree) of 'Catherine' peach trees, grown on 16 peach rootstocks following four different drip irrigation strategies were studied. The list of rootstocks used was as follows: Type I rootstocks (peach x almond hybrids) were: GF 677, Mayor, Adafuel, H 920, Monegro, Garnem and Felinem. Type II rootstocks (peach x davidiana hybrids) were: Barrier I and Cadaman. Type III rootstocks (plum tree "pollizo Murcia") were: Montizo, Monpol, Adesoto 101 and Pollizo comun. Type IV were other plum tree selections: Julior, Mr S 2/5 and Adara. Irrigation levels were: 100% ETc (R100) and 50% ETc (R50) over the annual crop cycle, 100% ETc until fruit harvest and 50% ETc postharvest (R175), 50% ETc until fruit harvest and 100% ETc postharvest (R275). The first year after grafting 3 (2000) the same quantity of irrigation water was applied to all treatments: 775 m(3)/ha. In the second year (2001), different irrigation regimes were applied: 2,513 m(3)/ha for treatment R100; 1,803 m(3)/ha for treatment R175; 1,687 m(3)/ha for treatment R275; and 1,212 m(3)/ha for treatment R50. Most water applied in treatment R100 was consumed via the evapotranspiration processes. Under all irrigation strategies, the vegetative growth of the hybrid rootstocks (Type I and Type II) was significantly higher than that of selected plum rootstock trees (Type III and Type IV). Fruit yields after one year for Type IV under R100 irrigation were significantly higher than for the remaining rootstock types. Nevertheless, when the amount of water applied was halved (R50) the decrease in fruit yield was higher than for hybrid rootstocks (Type I and Type II). This indicates high sensitivity to a lack of water. No significant differences in fruit production were found among hybrid rootstocks (Type I and Type II). However, under low irrigation regimes hybrid rootstocks showed very low fruit production. For all trees tested, Type III rootstocks (plum tree "pollizo of Murcia") were the most sensitive to water stress.