Investigating the Impact of Subsurface Irrigation on the Quantity and Quality of Four Grape Cultivars

Bakground and Objectives

Efficient use of water resources in agriculture is indeed vital for sustainability, especially in the face of climate change and increasing water scarcity. In regions with limited rainfall and high rates of evaporation, agricultural productivity can be severely impacted. This situation presents challenges but also opportunities for implementing effective strategies to mitigate losses and enhance resilience. Transitioning from surface to subsurface irrigation is indeed a highly effective solution for optimizing water management and improving irrigation efficiency, especially in regions facing water scarcity and high evaporation rates. Research indicates that grapevine flowering and fruit development are particularly sensitive to water availability. While numerous studies have explored subsurface irrigation for grape cultivation, there is a lack of research utilizing cement blocks to maintain optimal soil moisture in grape root zones. Subsurface irrigation not only mitigates the impact of water scarcity on crops but also reduces disease risk by maintaining lower humidity levels around plants. Subsurface irrigation is a powerful tool in modern agriculture that not only addresses the challenges of water scarcity but also contributes to healthier crop environments by reducing humidity levels and minimizing disease risks. By maintaining optimal soil moisture and preventing excessive leaf wetness, subsurface irrigation helps promote plant health and resilience, leading to improved yields and sustainable agricultural practices. As farmers increasingly adopt this method, they can better navigate the challenges posed by climate variability and water availability, ensuring a more sustainable future for agriculture. This study aims to examine the effects of subsurface irrigation on the yield of different grape cultivars, comparing it with traditional irrigation methods. The research was conducted using a complete block design in Khalil Abad city.
Methodology
The study was carried out from 2019 to 2021, encompassing both laboratory and field experiments. The laboratory component employed a factorial design in a completely randomized format with four replications at the Faculty of Agriculture, University of Torbet Heydarieh . The research focused on the impact of subsurface irrigation on the performance of four grape cultivars (Pikani, Askari, Lal, and Torkaman4). The main treatment involved testing subsurface irrigation using cement blocks to influence the vegetative indicators of the grapevines, while traditional irrigation served as the control. A channel 50 cm deep was created to align with the depth of the tree roots. During the fruit ripening phase, 10 uniform grape bunches were randomly selected from each experimental unit to measure physiological indicators, including the number of bunches, bunch weight, number of berries per bunch, and individual berry weight. Additionally, sugar content, acidity, and water use efficiency were assessed.
Findings
Analysis of variance revealed that both the simple effect of irrigation and the interaction between cultivar type and irrigation significantly influenced the number of clusters per plant at the 5% probability level. Subsurface irrigation yielded the highest number of clusters per plant, with an average of 22 clusters, compared to 14 clusters for traditional irrigation. This increase in cluster number is attributed to subsurface irrigation’s ability to minimize competition between the grapevines and surrounding weeds. However, traditional irrigation produced heavier clusters, suggesting that while subsurface irrigation improves water efficiency and increases cluster quantity, it may not provide sufficient energy for optimal cluster weight. The findings underscore the importance of understanding the effects of irrigation methods on grapevine productivity and quality. Subsurface irrigation offers significant advantages in terms of increasing the number of clusters per plant by reducing competition from weeds. However, it may not provide the optimal conditions for achieving the heaviest clusters. Thus, careful consideration of irrigation strategies, cultivar selection, and overall vineyard management is essential for achieving the desired balance between quantity and quality in grape production.
The highest number of grapes was also recorded with subsurface irrigation, with traditional irrigation following. Among the cultivars, Asgari and Pikani produced the most grapes. The ratio of leaves to grapes is crucial for the overall yield and quality of grapes. Subsurface irrigation enhanced grape production by reducing water evaporation, improving fertilizer efficiency, decreasing total water needs, limiting weed growth, and preventing surface salt accumulation. Furthermore, subsurface irrigation improved the taste quality of the grapes, as excessive water from traditional irrigation can diminish color, sugar content, and overall nutritional quality. Water use efficiency was notably higher with subsurface irrigation compared to traditional methods, which inversely affected water flow.
Conclusion

The study’s findings highlight the significant advantages of subsurface irrigation compared to traditional irrigation methods, particularly in terms of water conservation and the quality of grape fruit. Let’s break down the key points and elaborate on the implications of these findings. The study concluded that subsurface irrigation resulted in a 73% reduction in water usage compared to traditional irrigation, which only accounted for 27% of the total water consumption. Given the preservation and enhancement of various quality characteristics of grape fruit, it is recommended to adopt subsurface irrigation methods over traditional approaches.