REGULATED DEFICIT IRRIGATION ON FINO LEMON TREES
Mature lemon trees (Citrus limonum L. cv. Fino) were grown at Santomera (Murcia) under field conditions. The trees were submitted at two different drip irrigation treatments : 100% of ETc all year (control treatment) and 25% of ETc all year, except during rapid fruit growth period (stage II) when 100% of ETc was applied (regulated deficit irrigation, RDI, treatment). Water applied to control treatment was around 630 mm and a 30% less water to RDI treatment. Predawn leaf water potential resulted dependent of irrigation conditions. Clear differences between treatments were noted during periods of deficit irrigation. Main periods of shoot growth occurred before rapid fruit growth began. Lemon fruit growth was similar in both treatments. Water deficits induced by RDI out of stage II did not affect fruit growth dynamics. The decline of relative growth rate of fruit diameter coinciding with the begining of rapid fruit growth stage can be used as a tool which allows to schedule more scientific and precisely RDI strategies for lemon trees. Total yield was similar in both treatments. However, in the first pick an important reduction on yield per tree was obtained in RDI treatment with a paralell reduction in the number of fruits per tree. This fact can be ascribed to the effect of water deficit on flowering-fruit set period. These results, which require confirmation by additional years of study, show that this RDI strategy had no impact on total yield of Fino lemon trees, save irrigation water, and consequently improve the water use efficiency.
Torrecillas, A., Ruiz-Sánchez, M.C., Hernández-Borroto, J. and Domingo, R. (1993). REGULATED DEFICIT IRRIGATION ON FINO LEMON TREES. Acta Hortic. 335, 205-212