Influence of deficit irrigation and reflective mulch on 'Konservolea' olive leaf physiology during the growing period

Abstract

Scarcity of irrigation water in the Mediterranean region calls for the development of methods to reduce water use for agricultural production. Deficit irrigation and mulching above the irrigated zone could potentially result in water savings in the extensively cultivated olive. We examined the effect of deficit irrigation and reflective mulch on leaf physiology of 25-year-old 'Konservolea' olive trees during the 2008 growing season. We tested four different treatments: control (irrigated with >100% ET o), deficit irrigation (30% of control from late July to early September), Extenday reflective mulch on the tree row (from mid July) and their combination. The measured or calculated leaf physiological parameters were: specific leaf weight and chlorophyll a and b content (in late July and early September in concurrent and previous year's leaves), chlorophyll fluorescence, and photosynthetic parameters: photosynthetic and transpiration rates, stomatal conductance, leaf temperature, water-use efficiency and quantum yield (2 days after an irrigation event in late July and late August). Leaf total chlorophyll decreased over the growing period, especially in leaves of the previous year's deficit-irrigated trees. Specific leaf weight, chlorophyll fluorescence ratio (Fv/Fm, a common stress indicator) and leaf temperature were similar soon after treatment initiation (July) and after the 1-month deficit period (August). In contrast, transpiration and photosynthetic rates and stomatal conductance decreased over the growing period in all treatments. Deficit irrigation, reflective mulch and their combination negatively affected most of the physiological leaf parameters including photosynthetic rate, stomatal conductance, quantum yield and, to a lesser extent, transpiration rate, water-use efficiency and Fv/Fm. These results indicate loss of leaf productivity due to the applied treatments.