Leaf Growth in 'Algerie' Loquat under Full and Summer Deficit Irrigation

Loquat is a model crop for successful deficit irrigation (DI). Withholding irrigation during a period of 6-8 weeks in summer advances entrance and release of bud dormancy and consequently bloom and harvest dates. Strikingly, we have failed in different occasions in detecting significant effects of DI on the size of the leaf blade, the most sensitive character to DI according to many authors. In this work, we report the results of careful and frequent measurements (twice per week) of leaf growth, length and width in 'Algerie' trees under full irrigation versus summer DI. The results show that: (1) leaves took 3 weeks to reach their final size in both treatments, with about 90% of the length and 75% of the width reached within 2 weeks; (2) leaf growth in length and width followed the same trends in both irrigation treatments fitting a logistic curve; and (3) DI reduced by 13% the area of those leaves that were at the primordial stage when DI was imposed. In spite of the minor non-significant effects of summer DI on leaf growth and size, DI trees bloomed 18 days earlier than fully irrigated trees. The results are discussed in the context of shoot growth, bud dormancy, and blooming.