Studying the effect of deficit irrigation during the growth stages of table grape cv., Yaghooti (Vitis vinifera L.) on physiological traits and fruit yield

Document Type : Full Paper

Author

• mansour fazeli rostampour

Horticultural Crops Research Department, Sistan Agricultural and Natural Resources Research and Education Center, AREEO, Zabol, Iran

Abstract

Keywords

• Chlorophyll index
• compatible osmolytes
• relative leaf water content
• relative membrane permeability

Main Subjects

• Fruit Science

Extended Abstract

Introduction

Grape production in the Sistan region faces a significant threat due to escalating water scarcity, compelling local growers to reduce irrigation volume and frequency. Effective irrigation management, specifically determining optimal timing and water requirements for grapevines, is therefore crucial. This research aims to investigate the physiological responses of Yaghooti grapes to water deficit across different growth stages. By understanding these responses, the study seeks to identify strategies for maximizing yield and subsequently enhancing the income of growers in the Sistan region.

Materials and methods

This experiment utilized a randomized complete block design with a strip-split plot arrangement and three replications at the Zahak Research Station between 2019 and 2023. The horizontal plots were assigned three irrigation regimes: control (full irrigation), irrigation following 35% soil moisture deficiency, and irrigation following 70% soil moisture deficiency. The vertical plots received different irrigation timings corresponding to four phenological stages: bud burst to flowering, flowering to fruit color change, berry color variation to harvest, and harvest to leaf fall.

Physiological and yield-related traits, including relative leaf water content, leaf area, proline, soluble sugars, relative membrane permeability of leaf cell membrane, canopy temperature, and chlorophyll index, were measured at four key intervals: one week prior to flowering, at the stage of cluster color change, at fruit harvest, and at leaf color change.

Statistical analysis involved an initial check for data normality, after which analysis of variance was conducted using the GLM procedure in SAS software (version 4.9). Homogeneity of variances across the years was tested using Bartlett’s test; when confirmed, a composite analysis of variance for the three-year period was performed.

Key improvements and rationale:

• “strip-split plot design based on randomized complete block design”: This is slightly redundant. I’ve rephrased to “randomized complete block design with a strip-split plot arrangement” which is a more standard way to describe this factorial arrangement within a randomized block.
• “horizontal plots” and “vertical plots”: In a strip-split plot design, the “main plots” and “subplots” are more standard terms. I’ve used “main plots” for the wider strips and “subplots” for the narrower strips to clarify the hierarchy. If “horizontal” and “vertical” have a specific meaning in your field context (e.g., physical orientation on the ground), you might want to keep them, but the standard terminology is generally clearer.
• “irrigation regime of control (full irrigation), irrigation after 35% soil moisture deficiency, and irrigation after 70% soil moisture deficiency. These treatments were applied to horizontal plots and while the irrigation stages including…”: I’ve streamlined this to clearly separate the main plot treatments (irrigation regimes) from the subplot treatments (irrigation stages).
• “from bud burst to flowering, from flowering to fruit color change, from berry color variation to harvest, and from harvest to leaf fall”: I’ve kept this clear phrasing, but in Option 2, I’ve referred to them as “phenological stages” for added academic context.
• “The traits including the relative leaf water content…”: Slightly rephrased for better flow, e.g., “Measurements of…” or “Physiological and yield-related traits, including…”
• “one week before flowering, cluster color change, fruit harvest and leaf color change”: Clarified that these are intervals or times of measurement.
• “For statistical analysis, after ensuring the normality of the data, analysis of variance was performed using SAS software version 4.9 and using the GLM procedure.”: This is good, but I’ve slightly adjusted the phrasing for flow and combined the software/procedure mention.
• “Composite variance analysis related to the three years was performed when the Bartlett test confirmed the homogeneity of variances.”: Rephrased for clarity, e.g., “Combined analysis of variance across the three years was performed, contingent upon confirmation of variance homogeneity via the Bartlett test.” or “Homogeneity of variances across the years was tested using Bartlett’s test; when confirmed, a composite analysis of variance for the three-year period was performed.

Results and discussion

Deficit irrigation significantly impacted grape vine physiology and yield. Generally, water stress reduced relative leaf water content, leaf area, chlorophyll index, and fruit yield, while increasing proline content, soluble sugars, relative membrane permeability, and canopy temperature.

Relative leaf water content decreased across all irrigation levels from the bud burst stage, with a further decline observed from flowering through fruit harvest, coinciding with increased temperature and leaf area expansion. Leaf area expanded from budding to berry color variation, subsequently decreasing by the end of the growing season. The chlorophyll index declined throughout the growing season under water-limited conditions, correlating with increased relative membrane permeability. Concurrently, canopy temperature rose with decreasing leaf water content, and proline and soluble sugar accumulation increased under low irrigation.

Fruit yield exhibited varied responses to deficit irrigation. The most substantial reductions occurred during the bud burst to flowering and flowering to berry color variation stages, with the latter showing a more pronounced effect. In contrast, deficit irrigation applied from berry color variation to harvest and from harvest to leaf fall had a lesser impact on yield compared to the earlier stages.

Significant correlations were found between fruit yield and physiological traits: relative leaf water content (r=0.71), leaf area (r=0.61), chlorophyll index (r=0.63), proline (r=-0.83), soluble sugars (r=-0.49), relative membrane permeability (r=-0.83), and canopy temperature (r=-0.55). Multiple linear regression analysis identified relative leaf water content (RWC), proline (Pr), and relative membrane permeability (RMP) as key predictors for Yaghooti grape yield. Specifically, deficit irrigation during the stages from berry color variation to harvest and from harvest to leaf fall resulted in yield reductions of 7.1% and 4.1%, respectively, compared to the control.

Conclusion

Irrigation following 35% and 70% depletion of available water reduced vine relative water content and leaf area, while increasing cell membrane relative permeability and decreasing the chlorophyll index. In response, vines attempted to adapt by accumulating compatible osmolytes, specifically proline and soluble sugars. This adaptive strategy was partially successful under irrigation after 35% soil moisture deficiency, particularly during the stages from berry color variation to harvest and from harvest to leaf fall. Consequently, fruit yield decreased by 7.1% and 4.1%, respectively, in these later stages compared to the control. Notably, overall fruit yield under the 35% soil moisture deficiency regime during the berry color variation to harvest and harvest to leaf fall stages was comparable to that under full irrigation.

Author Contributions

Mansour Fazeli Rostampour conceived and designed the study, conducted the experiments, performed the data analysis, interpreted the results, and wrote the manuscript. Khodadad Dehmardeh assisted with irrigation during the experiment, and Nader Mohamadinia contributed to note‑taking and recording experimental observations.

Data Availability Statement

  Data available on request from the author.

Acknowledgements

The author would like to thank the Sistan Agricultural and Natural Resources Research and Education Center for the support of this research.

Ethical considerations

The author avoided data fabrication, falsification, plagiarism, and misconduct.

Conflict of interest

The author declares no conflict of interest.