Water Deficit Timing Affects Physiological Drought Response, Fruit Size, and Bitter Pit Development for 'Honeycrisp' Apple.

Michelle Reid,Lee Kalcsits

doi:10.3390/plants9070874

Michelle Reid, Lee Kalcsits

Open Access

https://doi.org/10.3390/plants9070874

Copy DOI

Abstract

Irrigation is critical to maintain plant growth and productivity in many apple-producing regions. ‘Honeycrisp’ apple characteristically develops large fruit that are also susceptible to bitter pit. Limiting fruit size by restricting irrigation may represent an opportunity to control bitter pit in ‘Honeycrisp’. For three seasons, ‘Honeycrisp’ trees were subject to water limitations in 30-day increments and compared to a fully watered control. Water limitations were imposed from 16–45, 46–75, and 76–105 days after full bloom (DAFB). Soil moisture for the well-watered control was maintained at 80–90% of field capacity for the entire season. For two years, physiological measurements were made every 15 days from 30 to 105 DAFB. Fruit quality, bitter pit incidence, shoot length, and return bloom were also measured to assess impacts on growth and productivity. When water was limited, stomatal conductance and net gas exchange were lower compared to the well-watered control and stem water potential decreased by 30–50% throughout the growing season. Early season water limitations had a lower impact on plant response to abiotic stress compared to late-season limitations. Overall, water deficits during fruit expansion phases contributed to fewer large fruit and decreased overall bitter pit incidence with no negative effects on fruit quality.

Highlights

Irrigation is critical to maintain plant growth and productivity in many apple-producing regions.In the future, water limitations may drive the adoption of irrigation strategies that use less water but, at the same time, minimize reductions in fruit size
Water deficits during fruit expansion phases contributed to fewer large fruit and decreased overall bitter pit incidence with no negative effects on fruit quality
‘Honeycrisp’ fruit can be oversized, especially in younger trees. It exhibits strong alternate bearing where fruit size can be even greater in a low-bearing year [2]. This oversized fruit can contribute to an increase in susceptibility to physiological disorders like bitter pit, a calcium-related disorder associated with mineral nutrient imbalances and low fruit calcium content

Summary

Introduction

Irrigation is critical to maintain plant growth and productivity in many apple-producing regions. Water limitations may drive the adoption of irrigation strategies that use less water but, at the same time, minimize reductions in fruit size. ‘Honeycrisp’ fruit can be oversized, especially in younger trees. It exhibits strong alternate bearing where fruit size can be even greater in a low-bearing year [2]. This oversized fruit can contribute to an increase in susceptibility to physiological disorders like bitter pit, a calcium-related disorder associated with mineral nutrient imbalances and low fruit calcium content. Bitter pit has been reported to correspond with fruit size because of the calcium dilution effect from fruit expansion [3]

Methods

Results

Discussion

Conclusion