Effects of Different Nitrogen Forms on Blackberry Fruit Quality

Area of Science:

• Horticulture
• Plant Nutrition
• Agricultural Science

Background:

• Optimizing nitrogen (N) application and harvest timing is crucial for maximizing blackberry fruit yield and quality.
• Understanding the differential effects of nitrogen forms (ammonium vs. nitrate) on fruit development is essential for growers.

Purpose of the Study:

• To investigate the impact of different nitrogen (N) fertilizers on blackberry fruit characteristics.
• To determine the optimal harvest period for blackberries to achieve desired fruit quality attributes.

Main Methods:

• Blackberry plants were treated with different forms of nitrogen fertilizers during their critical growth phase.
• Fruit quality parameters including size, firmness, color, soluble solids, sugars, anthocyanin, ellagic acid, flavonoids, vitamin C, organic acids, and antioxidant capacity were analyzed.
• Fruit quality was assessed across different harvest dates throughout the growing season.

Main Results:

• Ammonium-nitrogen (NH₄⁺-N) application significantly improved fruit appearance (size, firmness, color) and promoted the accumulation of soluble solids, sugars, anthocyanin, ellagic acid, and vitamin C (VC).
• Nitrate-nitrogen (NO₃^--N) application led to higher accumulation of flavonoids and organic acids, with enhanced antioxidant capacity.
• Fruit size, firmness, and color brightness decreased as the harvest season progressed. Early harvests had higher sugar, anthocyanin, ellagic acid, flavonoid, and VC content, while later harvests showed increased total antioxidant capacity and DPPH radical scavenging capacity.

Conclusions:

• Application of NH₄⁺-N is recommended for superior blackberry fruit appearance, taste, and nutritional quality.
• Early-stage harvests are optimal for fruit appearance, whereas middle to late-stage harvests benefit fruit taste and quality.
• Findings provide valuable insights for blackberry growers to optimize fertilization strategies and harvest schedules based on specific quality targets.