Effects of irrigation mode on photosynthetic characteristics and fruit quality of apricot

【Objective】Xinjiang is a pivotal region for apricot cultivation. However, agricultural water use has become an increasingly pressing issue due to severe aridity and irrational water resource utilization structure. Traditional flood irrigation tends to cause substantial water evaporation, soil structural degradation, and resource waste, while drip irrigation technology provides a feasible solution for improving water use efficiency. Furthermore, well irrigation minimizes surface evaporation by delivering water directly to the root zone. This experiment investigates the effects of different irrigation regimes on the leaf characteristics, photosynthetic characteristics, and fruit quality of Prunus armeniaca‘Luntaibaixing’. The objective is to determine an optimal irrigation strategy that achieves water conservation and improves efficiency for apricot production in arid regions.【Methods】The test material was ‘Luntaibaixing’, with a tree age of 4 years and uniform growth. The experiment was conducted at the experimental station of the Institute of Fruits and Vegetables, Xinjiang Academy of Agricultural Sciences, located in Haerbake Township, Luntai County, Xinjiang. A split-plot design was adopted, where the main-plot factor was irrigation mode (well irrigation, drip irrigation, and flood irrigation) and the subplot factor was irrigation volume. Three irrigation levels were established: high (W1), medium (W2), and low (W3), resulting in a total of nine treatment combinations. Each treatment was replicated three times, and six apricot trees per plot were designated as the observational units. The specific irrigation quotas were defined as follows: well irrigation (JW1: 310 m3 · 666.7 m-2 , JW2: 230 m3 · 666.7 m-2 , JW3: 150 m3 · 666.7 m- 2 ); drip irrigation (DW1: 310 m3 · 666.7 m- 2 , DW2: 230 m3 · 666.7 m- 2 , DW3: 150 m3 · 666.7 m- 2 ); and flood irrigation (MW1: 500 m3 · 666.7 m- 2 , MW2: 350 m3 · 666.7 m- 2 , MW3: 200 m3 · 666.7 m- 2 ).【Results】Analyses of leaf phenotype and chlorophyll content showed that the MW1 treatment achieved the best leaf growth performance, with both leaf length and leaf area significantly larger than those under other treatments. Under water-saving conditions, the DW2 treatment showed no significant difference in leaf area compared with DW1. Furthermore, its leaf length and width were comparable to those of MW1, demonstrating a strong compensatory growth effect. In contrast, the JW3 treatment had the lowest values for leaf length, leaf area, and SPAD. Light- response curves revealed that MW1 had the highest maximum net photosynthetic rate (Pn max) and light saturation point (LSP), indicating superior photosynthetic potential. Despite reduced water application, DW2 exhibited maximum Pn, LSP, and electron transport rate (ETR) values comparable to those of DW1 and MW1. This suggests that DW2 would maintain high photochemical efficiency and robust photosynthetic capacity even under water-saving constraints. In contrast, the Pnmax and LSP of JW3 were approximately 24.7% and 30.7% lower than those of MW1, respectively. Similarly, compared with MW1, MW3 showed an approximate 18.3% reduction in Pn max and 9.4% reduction in LSP. Fruit quality assessments indicated that the MW1 treatment resulted in the optimal single fruit weight, along with the highest levels of total phenols, flavonoids, and vitamin C. However, this treatment requires substantial water consumption. Notably, DW2 maintained fruit quality comparable to that of the high-water treatments, demonstrating excellent water use efficiency. Photosynthetic fluorescence parameters were significantly correlated with the contents of soluble solids, total phenols, and flavonoids. These correlations indicate that photosynthetic efficiency directly affects the accumulation of sugars and secondary metabolites (such as phenols and flavonoids) in fruits, and these components are essential for fruit nutrition and sensory quality. In addition, ΦPSⅡ was positively correlated with the soluble solids content, indicating that higher photosynthetic efficiency directly promoted the accumulation of sugar in the fruit. While there was a substantial disparity in fruit quality between JW1 and MW1, JW1 was more comparable to DW2. Although differences persisted: JW1 exhibited lower fruit firmness, soluble solid concentration, and total phenol concentration compared with DW2, with reductions of 18.8% , 7.8% , and 17.6% , respectively.【Conclusion】The combination of drip irrigation with a medium- high irrigation volume range (230-310 m3 · 666.7 m- 2 ) achieves an optimal balance between water conservation and production efficiency, and is identified as the superior irrigation strategy for apricot cultivation in arid regions. This approach sustains vigorous vegetative growth and high fruit quality while significantly cutting water consumption, demonstrating superior water use efficiency. Future experiments should focus on further refining irrigation regimes within this volume range to support the sustainable development of the apricot industry.