Silicon enhances quality and yield of raspberry and calcium uptake in the development of raspberry and blackberry fruits

Abstract

The current study focused on mineral nutrition of caneberry, specifically investigating the effects of silicon and calcium. The primary aim of the initial study was to assess the influence of silicon (Si) on the growth and quality of raspberry (Rubus idaeus). The secondary objective was to determine the specific timing and duration of peak calcium (Ca) absorption in raspberry and trailing blackberry (Rubus subgenus Rubus) fruits, in order to provide guidance for optimizing fertilizer application strategies. The initial trial consisted of seven distinct treatments, which were randomly assigned to four separate blocks within a location characterized by a subtropical climate. Each treatment had three pots with a 'Batum' primocanefruiting raspberry plant. In 2020, the soil was treated with different concentrations of Si (0, 50, 100, 200, 400, 800, or 1600 mg dm-3) 15 days after transplanting. In the second experiment conducted in 2022, samples of fruits were collected across seven different phases of development from three floricane-fruiting raspberry ('Meeker,' 'WakeField,' and 'WakeHaven') and three blackberry ('Marion,' 'Black Diamond,' and 'Columbia Star') cultivars. The initial research involved doing field analyses that encompassed the quantification of chlorophylls a and b, leaf water potential, and yield. The study of the fruit encompassed parameters such as color, firmness, respiration frequency, soluble solids, and pH. The findings indicated that the use of Si fertilization resulted in a significant augmentation in both the quantity of fruits and raspberry yield per plant. Si enhanced fruit yield and firmness, but concurrently reduced water potential and respiratory rate. The second study revealed that the highest absorption of Ca in raspberry cultivars occurred between the S4 stage (middle developed/"immature green") and S6 stage (immature fruit/"white fruit"). In 'Black Diamond' blackberries, the peak absorption occurred between S4 and S5 stages (mature green), while in 'Columbia Star' and 'Marion' blackberries, it occurred between S4 and S6 stages. These findings suggest that applying Ca fertilizer during the S4 to S6 stages would be most effective, as it aligns with the periods of highest uptake by plants.