The position in the canopy and the bearing status of 1-year-old shoots affect the bearing potential and morphology of current-year shoots in walnuts (Juglans regia L.) cv. Chandler
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From 1 year to the next the number of shoots increases, but their individual size declines. Shoots located in more lightened canopy zones and bearing two fruits maintain productive sustainability.
432 shoots in 24 mature trees from three commercial orchards located in the central valley of Chile were inspected for 2 years. Tree canopy was divided into three zones according to light exposure (upper, lower-exposed, lower-shaded). In the first year of the study, six shoots were randomly selected in each canopy zone and divided into three bearing statuses [shoots bearing one fruit (F1), shoots bearing two fruits (F2), and shoots bearing three fruits (F3)]. In the second year, all new shoots (1068) born on the 432 shoots were studied. Specific leaf weight and current-year shoots (CY) characteristics (length, diameter, number of leaves, number of leaflets, leaf area) were evaluated as a function of the previous season fruit load and canopy position of the 1-year-old (1Y) shoots. The results indicated that 1Y shoots located in more light-exposed canopy zones bore on average 0.5 more CY shoots than 1Y shoots in the lower-shaded canopy zone. Specifically, the 1Y shoot probability of bearing CY shoots that had two or three fruits was 72.8% in the upper canopy zone, 44.6% in the lower-exposed zone, and 34.9% in the lower-shaded zone of the canopy, respectively. 1Y shoots in the lower-shaded zone had on average a 7.7% higher probability of dying than 1Y shoots in the upper and exposed positions. In addition, CY shoots born on 1Y shoots exposed to light were on average 2.7 cm longer, more than 1 mm thicker, and had 53.7% greater leaf area than CY shoots born on shaded 1Y shoots. Finally, the results of this study showed that 1Y shoots that had two fruits in the previous season produced CY shoots with the greatest bearing potential in the current and future seasons.
KeywordsBearing structure Light Leaf area Source Sink
The authors would like to thank Chilenut AG for the Specific Agreement which financed the project called “Estudio del crecimiento y morfología de las ramillas del nogal en plena producción para la evaluación de los principales componentes de rendimiento”.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- CDFA (2014). 2013 California walnut nursery sales report. California Department of Food and Agriculture. Sacramento. USAGoogle Scholar
- DeJong TM, Doyle JF (1985) Seasonal relationships between leaf nitrogen-content (photosynthetic capacity) and leaf canopy ligh exposure in peach (Prunus persica). Plant Cell Environ 8:701–706Google Scholar
- Embree CG, Myra MTD (2007) Effect of blossom density and crop load on growth, fruit quality, and return bloom in ‘Honeycrisp’ apple. HortScience 42:1622–1625Google Scholar
- Hackett WP (1985) Juvenility, maturation, and rejuvenation in woody plants. Hortic Rev 7:109–155Google Scholar
- Hampson CR, Azarenko AN, Potter JR (1996) Photosynthetic rate, flowering, and yield component alteration in hazelnut in response to different light environments. J Am Soc Hortic Sci 121:1103–1111Google Scholar
- Heerema RJ, DeJong TM, Weinbaum SA (2004) Almond spur autonomy: leaf growth, floral initiation and spur survival. HortScience 39:851–851Google Scholar
- Klein I, Dejong TM, Weinbaum SA, Muraoka TT (1991a) Specific leaf weight and nitrogen allocation responses to ligh exposure within walnut trees. HortScience 26:183–185Google Scholar
- Klein I, Weinbaum SA, Dejong TM, Muraoka TT (1991b) Relationship between fruiting, specific leaf weight, and subsequent spur productivity in walnut. J Am Soc Hortic Sci 116:426–429Google Scholar
- Kon TM, Schupp JR (2013) Thinning tall spindle apple based on estimations made with a hand-thinning gauge. Horttechnology 23:830–835Google Scholar
- Lampinen B, Upadhyaya S, Udompetaikul V, Browne G, Roach J, Metcalf S, Stewart W, Contador L, Negron C, Gómez IP, Beede B, Debuse C, Doll D, Duncan R, Edstrom J, Elkins R, Fichtner E, Grant J, Hasey J, Holtz B, Kelley K, Krueger B, Niederholzer F, Olson J (2014) A second generation mobile platform for assessing midday canopy photosynthetically active radiation interception in orchard systems. Acta Hortic 1058:105–112CrossRefGoogle Scholar
- Ramos D (1998) Walnut production manual. University of California, USAGoogle Scholar
- Reid W, Huslig SM, Smith MW, Maness NO, Whitworth JM (1993) Fruit-removal time influences return bloom in pecan. HortScience 28:800–802Google Scholar
- Rohla CT, Smith MW, Maness NO (2007) Influence of cluster thinning on return bloom, nut quality, and concentrations of potassium, nitrogen, and non-structural carbohydrates. J Am Soc Hortic Sci 132:158–165Google Scholar
- Ryugo K, Marangoni B, Ramos DE (1980) Light-intensity and fruiting effects on carbohydrate contents, spur development, and return bloom of Hartley walnut. J Am Soc Hortic Sci 105:223–227Google Scholar
- Sabatier S, Barthelemy D, Ducousso I, Germain R (1998) Modes of shoot extension and morphology of annual shoots in the persian walnut, Juglans regia L. ‘Lara’ (Juglandaceae). Can J Bot 76:1253–1264Google Scholar
- Tombesi S, Lampinen BD, Metcalf S, DeJong TM (2015) Spur fruit set is negatively related with current-year spur leaf area in almond. HortScience 50:322–325Google Scholar
- USDA (2016) 2015 California walnut acreage report. United States Department of Agriculture, National Statistics Service. Sacramento. USAGoogle Scholar
- Verreynne JS, Lovatt CJ (2009) The effect of crop load on budbreak influences return bloom in alternate bearing ‘Pixie’ Mandarin. J Am Soc Hortic Sci 134:299–307Google Scholar
- Whiting MD, Lang GA (2004) ‘Bing’ sweet cherry on the dwarfing rootstock ‘Gisela 5’: Thinning affects fruit quality and vegetative growth but not net CO2 exchange. J Am Soc Hortic Sci 129:407–415Google Scholar