Combined effects of deficit irrigation and crop level on early nectarine trees

Abstract

A three-year long experiment was implemented in an early nectarine (Prunus persica L. Batsch cv. Flanoba) commercial orchard to evaluate the effects of deficit irrigation and different crop levels on vegetative growth, plant water status, and fruit yield and quality. Three irrigation treatments were assessed: (i) control, full irrigation (T CTL); (ii) normal practice of the farmer (T FRM); and (iii) regulated deficit irrigation (T RDI), which involved irrigating the crop at the same level as the control (T CTL) during the critical periods of the first year and at 60% T CTL during postharvest. In the last two growing seasons the irrigation was scheduled to maintain the signal intensity (SI) of maximum daily trunk shrinkage (SI MDS = MDS TRDI /MDS TCTL) at different water stress levels depending on the phenological stage: SI = 1.0 (non-water stress) and SI = 1.4 (moderate water stress). Besides, during the last two seasons, the interactions between T CTL and T RDI were studied at five different crop levels, which were obtained by controlling the distance between fruits left on the branches: from very low (16 cm between fruits) to very high (8 cm between fruits). Crop water use efficiency (WUE) of T RDI was higher than in T CTL and T FRM , increasing by around 25% in 2010 and 2011, and around 74% the final year. Interestingly, T FRM increased the WUE from the first year by more than 30%. The yield/annual increase in trunk-cross-sectional area (TCSA) ratio increased in T RDI with respect to the other treatments as the experiment progressed, reaching differences of 53%. Vegetative growth was clearly sensitive to deficit irrigation with a strong correlation between the increase in the water stress integral obtained by midday stem water potential (stem) and the reduction in TSCA. In contrast, fruit production and quality were not affected by water deficit. As regards the interaction between crop level and water deficit, fruit firmness was the only fruit quality parameter studied that presented significant differences, the highest values corresponding to the fruits from T RDI trees and the lowest crop level. In early nectarine trees, the postharvest period can be considered as a non-critical period for applying RDI strategies but only when the water stress integral applied is of low intensity in May and June (much lower than 9 MPa day), in order to limit the decrease in vegetative growth and so not affect the following harvests.

Terrestrial and Remote Indexes to Assess Moderate Deficit Irrigation in Early-Maturing Nectarine Trees

“…In our study, the soil water deficit imposed in the PDI treatment did not affect the vegetative components studied (pruning, canopy tree cover, and TCSA) ( Table 1), as also reported by de la Rosa et al [10]. However, a reduction in tree size was noted in peach trees submitted to severe water deficits [13].…”

Irrigation Factor Approach Based on Soil Water Content: A Nectarine Orchard Case Study

“…A 15 min delay in data relay was to be expected, but occasionally greater amplitude in SWC oscillations was observed, especially at the beginning of June (late post-harvest) coinciding with the change of α to 30 % and the increase in evaporative demand ( Figure 1, Table 1). This post-harvest period is considered suitable for applying regulated deficit irrigation in early Prunus persica trees, because it is less sensitive to soil water deficits than the fruit growth period [40][41][42][43][44][45]. Post-harvest is the longest non-critical period, accounting for 80-86% of the water requirements needed for the entire irrigation season in these early Prunus cultivars [12,46], and it is important because carbohydrate reserves are accumulated and the floral differentiation process occurs during this time [47].…”

Deficit Irrigation in Mediterranean Fruit Trees and Grapevines: Water Stress Indicators and Crop Responses

“…More recently, the benefits of applying RDI during stage II of fruit development have also been stated [89], including beneficial reduction of tree vigor and improvement of fruit quality [71]. De la Rosa et al [131] applied RDI after harvest, concluding that it was beneficial to control vegetative growth. Results from [70] also confirm the positive effects of RDI to control vegetative growth without a significant effect in fruit production.…”