Article | . 2017 Vol. 35, Issue. 6
The Role of Secondary-lateral Branch Leaves as a Source of Assimilates for Watermelon Fruit During Fruit Ripening Period



Department of Agricultural Science, Korea National Open University1
National Institute of Horticultural and Herbal Science2
Department of General Education, Korea National College of Agriculture and Fisheries3
Department of Vegetable, Korea National College of Agriculture and Fisheries4




2017.. 680:688


PDF XML




This study examined the contribution of leaves on the secondary-lateral branches to sucrose concentration in the fruit of watermelon (Citrullus lanatus ) ‘Sambok-kkul’. Plants were trained to two primary-lateral branches after topping the main stem, and treated with either removal of the entire secondary-lateral branch (treatment 2C), or removal of the secondary-lateral branch below the fruit set node (treatment 2C-1). On average, 2C-1 plants had 30% smaller leaves at the 5th node above fruit set on the primary-lateral branches (EL) at 3 weeks after pollination compared to the 2C plants. Total leaf area of 2C-1 plants was 26% higher, on average, however, due to the leaves on the remaining portion of the secondary-lateral branch. At 2 weeks after pollination, both the leaves on the primary-lateral branches of the EL of the 2C treatment plants and leaves on the secondary lateral branches (SL) of the 2C-1 treatment showed significantly higher photosynthetic activity than other leaves. However, at 4 weeks after pollination, the highest photosynthesis activity and lowest water potential were observed in the leaves on the secondary lateral branch SL of the 2C-1 treatment plants. The leaf sucrose content of the 2C-1 treatment plants started increasing much more steeply from 4 weeks after pollination, while there was no significant increase in the sucrose content under the 2C treatment at the same period. In particular, the sucrose content in the SL of the 2C-1 leaves became greater than that of the EL of the 2C leaves starting 3 weeks after pollination. There was a 3.9-fold increase in sucrose content of the 2C-1 fruit for 4 to 5 weeks after pollination, while there was only a 1.4- fold increase in the 2C fruit. Micrographs of harvested fruit flesh showed higher cellulose in the 2C fruit flesh than in 2C-1. These results suggest that a transition from sink to source of carbon in younger and older leaves may influence the availability of carbohydrates for fruit development and quality.



1. Candolfi-Vasconcelos MC, Koblet W (1990) Yield, fruit quality, bud fertility and starch reserves of the wood as function of leaf removal in Vitis vinifera – Evidence of compensation and stress recovering. Vitis 29:199-221  

2. Chang YH, Shim JS, Ro CW, Lim JM, Cho JL (2004) Effects of eliminating method of lateral branch on fruit characteristics and wilting symptom of watermelon in protected cultivation. Korean J Hortic Sci Technol 22:35  

3. Choi EY, Cho IH, Moon JH, Woo YH (2012) Impact of secondary-lateral branch removal during watermelon production. Hortic Environ Biotechnol 53:24-31  

4. Chrost B, Schmitz K (1996) Changes in soluble sugar and activity of α-galatosidases and acid invertase during muskmelon (Cucumis melo L.) fruit development. J Plant Physiol 151:41-50  

5. Elkashif ME, Huber DJ (1988) Electrolyte leakage, firmness, and scan-ning microscopic studies of watermelon fruit treated with ethylene. J Am Soc Hortic Sci 113:378–381  

6. Elmstrom GW, Davis PL (1981) Sugars in developing and mature fruits of several watermelon cultivars. J Am Soc Hortic Sci 106:330- 333  

7. Génard M, Dauzat J, Franck N, Lescourret F, Moitrier N, Vaast P, Vercambre G (2008) Carbon allocation in fruit trees: from theory to modelling. Trees Struct Funct 22:269-282  

8. Gifford RM, Evans LT (1981) Photosynthesis, carbon partitioning, and yield. Annu Rev Plant Physiol 32:485-509  

9. Heuvelink E, Buiskool RPM (1995) Influence of sink-source interaction on dry matter production in tomato. Ann Bot 75:381-389  

10. Hubbard NL, Huber SC, Pharr DM (1989) Sucrose phosphate synthase and acid invertase as determinations of sucrose concentration in developing muskmelon (Cucumis melo L.) fruits. Plant Physiol 91:1527-1534  

11. Hubbard NL, Pharr DM, Huber SC (1990) Sucrose metabolism in ripening muskmelon fruit as affected by leaf area. J Am Soc Hortic Sci 115:798-802  

12. Johnson JT, Iwang EU, Hemen JT, Odey MO, Efiong EE, Eteng OE (2012) Evaluation of anti-nutrient contents of watermelon Citrullus lanatus. Ann Biol Res 3:5145-5150  

13. Kato T, Fukumoto Y, Kinoshita S (1984) Effect of training, pinching and defoliation on the development and quality of fruit in watermelon ( ). Res Rpt Kochi Univ Agric Sci 33:83-90  

14. Lacointe A, Minchin PEH (2008) Modelling phloem and xylem transport within a complex architecture. Funct Plant Biol 35:772-780  

15. Lakso AN, Corelli-Grappadelli L (1992) Implications of pruning and training practices to carbon partitioning and fruit development in apple. Acta Hortic 322:231-240  

16. Lee SG, Ko KD, Lee CW (2005) Interaction of source-sink relationship for translocation and distribution of C14 carbohydrates in watermelon (Citrullus vulgaris ). J Korean Soc Hortic Sci 46:300-304  

17. McCollum TG, Huber DJ, Cantliffe DJ (1988) Soluble sugar accumulation and activity of related enzymes during muskmelon fruit development. J Am Soc Hortic Sci 113:399-403  

18. Murakami T, Inayama M, Kobayashi, KS (1982) Translocation and distribution of photoassimilates and relation of set fruit in cucumber. Natl Inst Agr Sci Rpt D 33:235-275  

19. Ramirez DR, Wehner TC, Miller CH (1988) Source limitation by defoliation and its effect on dry matter production and yield of cucumber. HortScience 23:704-706  

20. Redgwell RJ, Melton LD, Brasch DJ, Coddington JM (1992) Structures of the pectic polysaccharides from the cell walls of kiwifruit. Carbohydr Res 226:287-302