Potential Markers for Selecting Self-Eliminating Apple Genotypes

Area of Science:

• Horticultural Science
• Plant Physiology
• Agricultural Genetics

Background:

• Heavy blooming in apple trees leads to inefficient resource allocation and necessitates manual fruit thinning to ensure fruit quality.
• Developing apple cultivars with inherent fruitlet self-elimination capabilities offers a sustainable solution for yield and quality management.

Purpose of the Study:

• To investigate the biological distinctions between apple cultivars regarding blooming intensity and fruitlet load self-regulation.
• To identify potential markers for selecting apple genotypes with improved self-thinning characteristics.

Main Methods:

• Studied 19 apple cultivars from 2015-2017, evaluating fruitlet self-elimination dynamics, seed development, photosynthetic parameters, carbohydrate levels, and plant hormone concentrations.
• Assessed leaf and fruitlet ratios, carbohydrate accumulation in leaves, and hormone profiles (auxin, indole-3-acetic acid, zeatin, abscisic acid) under varying conditions.

Main Results:

• Cultivars with low fruitlet self-elimination exhibited fewer developed seeds per fruit but had a higher leaf-to-fruit ratio.
• Higher carbohydrate levels in leaves correlated with reduced fruitlet self-elimination.
• Heavy-blooming cultivars showed elevated auxin and indole-3-acetic acid/zeatin ratios, and lower abscisic acid during drought stress.

Conclusions:

• Specific biological parameters, including seed number, leaf-to-fruit area, carbohydrate status, and hormone profiles, can serve as predictive markers.
• These markers are valuable for selecting apple genotypes with desirable self-thinning traits, optimizing yield and quality without excessive manual intervention.