Reid Michelle, Kalcsits Lee
Tree Fruit Research and Extension Center, Washington State University, Wenatchee, WA 98801, USA.
Department of Horticulture, Washington State University, Pullman, WA 99164, USA.
Plants (Basel). 2020 Jul 9;9(7):874. doi: 10.3390/plants9070874.
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.
在许多苹果产区，灌溉对于维持植物生长和生产力至关重要。“蜜脆”苹果的特点是果实大，但也易患苦痘病。通过限制灌溉来控制果实大小可能是控制“蜜脆”苹果苦痘病的一个机会。在三个季节里，“蜜脆”苹果树以30天为增量受到水分限制，并与充分浇水的对照树进行比较。在盛花后16 - 45天、46 - 75天和76 - 105天施加水分限制。充分浇水的对照树的土壤湿度在整个季节保持在田间持水量的80 - 90%。在两年时间里，从盛花后30天到105天，每15天进行一次生理测量。还测量了果实品质、苦痘病发病率、新梢长度和来年开花情况，以评估对生长和生产力的影响。当水分受到限制时，与充分浇水的对照树相比，气孔导度和净气体交换较低，并且在整个生长季节茎水势下降了30 - 50%。与后期水分限制相比，早期水分限制对植物对非生物胁迫的响应影响较小。总体而言，果实膨大期的水分亏缺导致大果数量减少，总体苦痘病发病率降低，且对果实品质没有负面影响。
