Plant growth and fruit quality as affected by canopy locations in ‘Shiranuhi’ mandarin

Abstract

Fruit quality (soluble solids and acidity) and growth properties of fruiting branches in different canopy positions (upper, middle, and lower) of 'Shiranuhi' mandarin [(C. unshiu × C. sinensis) × C. reticulate] trees were determined during fruit maturation. Length, diameter, and number of leaves per fruiting branch increased in order from the upper, through the middle, to the lower parts of the canopy. Fruit diameter, fruit weight, pulp weight and pulp thickness were also highest in the upper part. Transverse sections of stem end protrusions in fruit from the upper, middle, and lower parts of the tree canopy were 37.3 ± 2.3 mm, 33.2 ± 0.2 mm and 32.1 ± 0.4 mm, respectively. Soluble solid content increased during fruit maturation at all locations within the canopy and was highest in the upper part. Likewise, acid content decreased with fruit maturity and was lowest in the lower part. These results suggested that harvesting be staggered starting with fruit from the upper part of the canopy as part of crop management in 'Shiranuhi' mandarin for direct effect on fruit quality.Additional key words: fruit maturation, fruit shape, pulp weight Hort. Environ. Biotechnol. 52(5):443-447. 2011.

Differences in Fruit Quality and Plant Growth of ‘Shiranuhi’ Mandarin Trees, Planted and Top-Grafted Stock

“…However, fruit diameter and length, height and width of stem end protrusions, fruit weight, pulp weight, pulp thickness, SSC and titratable acidity were highest in the upper part at the harvested time in both planted stock and topgrafted trees (Table 2). Similar to the findings of Moon et al (2011), it was found that these were highest in the upper part of the tree during 'Shiranuhi' mandarin fruit maturation.…”

“…Along the canopy positions (upper, middle, and lower) and branches with attached fruit were sampled from three trees for planted stock and from five trees for top-grafting at each farm (15-40 branches per canopy position) by 270 days after anthesis (DAA), and pooled for each position to analyze branch growth and fruit characteristics. The canopy positions were divided three parts such as upper, middle and lower by Moon et al (2011) indicated method. The leaf-fruit ratio was 100~120 for experimental orchards in both planted stock and top-grafting trees.…”

“…The difference of gradient by canopy location of 'Shiranuhi' mandarin trees was probably due to plant growth (Table 1) and differences in sink strength because of the number of grafting. Fruit growth has been shown to be closely related to the differential accumulation of photosynthates (Kadoya, 1973), endogenously applied gibberellins (Coggins Jr. et al, 1960;Kami et al, 1998) and number of seeds per fruit (El-Zeftawi, 1977), fruit load (Chikaizumi et al, 2000), soil moisture (Moon et al, 2008), rootstock (Moon et al, 2010) and canopy location (Moon et al, 2011). Therefore, fruit growth and quality are affected by double grafting on grafted satsuma mandarin trees, such as top-grafting in 'Shiranuhi' mandarin.…”

“…It ranges from 12.5~15.8 °Bx for SSC (Matsumoto, 2001), 0.8~1.2% for acidity and 200~300g for fruit weight (Moon, Ko, Han, Choi, & Kim, 2008). It also has an oval shaped fruit in which SSC and acidity are highest in the stylar end (Moon & Mizutani, 2002;Moon et al, 2008), and SSC, acidity and plant growth were highest in the upper part depending on canopy location (Moon et al, 2011).…”

“…It is one of the most important cultural practices for fruit thinning (Chikaizumi, Hino, & Yamashita, 2000; Kami, Inoue, & Fujiwara, 1998; Moon et al, 2011), production of high quality fruit by regulating soil moisture (Moon et al, 2008) and soil management (Kami et al, 1998 (Ikeda, 1990) and that harvesting be staggered starting with fruit from the upper part of the canopy (Moon et al, 2011). Therefore, the growth habit and fruit quality of the 'Shiranuhi' mandarin is easily influenced by environmental factors, cultural practices and rootstocks.…”