Modelling physiological and environmental factors regulating relative fruit set and final fruit numbers in apple trees

Abstract

Modeling physiological and environmental factors regulating relative fruit set and final fruit numbers in apple trees Chemical thinning of apple has been practiced for 50 years but it remains an unpredictable part of apple production with large variations from year to year and within years. Carbohydrate availability to support young fruitlet growth may play a significant role in apple tree response to chemical thinners, especially when the carbohydrate supply is the limiting factor for fruit growth. To address the carbohydrate component, we have tested the MaluSim simplified apple tree carbon balance model that integrates many environmental and tree physiological factors as a tool to predict chemical thinner response in field trials from 2000-2011. The model suggests that carbon supply-to-demand variations may explain some of the great variation in thinning spray response. Relative fruit set and final fruit number per tree were affected by the carbohydrate balance within two days before the spray and up to five days after. There was a period, 15-29 days after bloom that thinners showed higher action. The greater the carbohydrate supply relative to demand, the greater the relative set and the final fruit number. This suggested that carbohydrate supply-demand balance may be a baseline for thinner responses, and that integrative modeling of these balances can be useful in understanding variation in thinning responses. Apple relative fruit set and final fruit number per tree could be modeled relatively well with consideration of initial flower density, the carbohydrate balance model, and cumulative growing degree days since bloom.

CPSM: A Dynamic Simulation Model for Cucumber Productivity in Solar Greenhouse Based on the Principle of Effective Accumulated Temperature

“…The model takes into consideration the impact of crop variety and temperature on crop productivity. The simulation accuracy of the CPSM is generally consistent with other crop productivity models based on EAT in previous studies [13,20,22,23]. Furthermore, our analysis reveals that the NRMSE of simulated values compared to measured values ranging from 0.12% to 37.79% in terms of indicatorbased differences, and the MRE ranges from 0.11% to 32.67%.…”

“…Moreover, the algorithms for accumulating temperature models have evolved from simple summation of daily average temperatures to incorporating lower temperature thresholds for active accumulating temperature (AAT) and effective accumulating temperature (EAT) [12,13]. Currently, the effective accumulating temperature model has been applied in predicting the productivity of grain crops such as wheat [14,15], maize [16,17], and rice [18,19], horticultural crops like apples [20], cherries [21], citrus [22], walnuts [23], as well as ornamental crops such as tulips [13]. These applications have demonstrated high simulation accuracy, indicating the strong extrapolation ability of the effective accumulating temperature model.…”

Chemical thinning programs for 'Fuji Mishima' apple trees under black anti-hail net

“…When the initial flower bud load is high, thinning intensity also tends to be high, and vice-versa, as the high abundance of flowers leads to an enhanced demand for assimilates and an increased competition between plant growing organs (Greene, 2017;Lordan et al, 2019Lordan et al, , 2020. This pattern was observed in the present study since more treatments promoted fruitlet thinning in the first season, but only T4 and T5, in the second.…”

Almond Fruit Drop Patterns under Mediterranean Conditions

“…In addition, environmental factors, such as temperature, may also affect pollen germination [11] and, thus, flower drop. On the other hand, drops that occur 40-50 days after full bloom have been attributed to competition between fruits and vegetative parts that affect carbon and hormone balances [12,14,[37][38][39][40][41].…”