Effect of plant spacing and primocane number on photosynthesis and yield indices of Thornless blackberry (Rubus fruticosis aggr.)

Optimal management of environmental factors, especially sunlight, in the trellis type cultivation of raspberry is one of the ways to increase the yield and quality of the crop. In order to investigate the effect of planting distance and number of vegetative branches on photosynthetic parameters and yield of Thornless blackberry, a factorial randomized complete block experiment with 4 replications was conducted in the four-year-old commercial garden of blackberry, located in Sari. . Treatments were row spacing at two levels of 1.5 and 2.5 meters and the number of vegetative branches per plant at two levels of 4 and 6 branches. The results of mean comparison showed that the highest area of ​​five leaves (140.6 cm) was belonging to the planting distance of 2.5 m and four branches. The highest production of branches and plants was observed in planting distance of 2.5 m (1.74 and 8.65 kg), respectively. Fruits harvested from plants with planting distance of 1.5 m had the highest amount of total anthocyanins, antioxidant activity, fruit size and the highest rate of photosynthesis (with an average of 5.58 μmol /m2.s). Also, the lowest leaf temperature (32.5°C) was recorded in this treatment. According to the results of his study, by reducing the distance between the raspberry plants, reducing the leaf temperature leads to an increase in photosynthesis rate and potential yield per branch. Conversely, at greater planting intervals, an increase in the number of branches is necessary to compensate the density and thus increase the total yield per hectare.