ISHS Acta Horticulturae 792: V International Symposium on Irrigation of Horticultural Crops
EFFECTS OF REGULATED DEFICIT IRRIGATION ON WALNUT GRAFTED ON 'NORTHERN CALIFORNIA BLACK' OR 'PARADOX' ROOTSTOCK |
| Authors: | R.P. Buchner, A.E. Fulton, C.K. Gilles, B.D. Lampinen, K.A. Shackel, S.G. Metcalf, C.C. Little, T.L. Prichard, L.J. Schwankl |
| Keywords: | Juglans regia, Juglans hindsii, paradox, midday stem water potential, water stress, pressure chamber |
| DOI: | 10.17660/ActaHortic.2008.792.14 |
| Abstract:
'Chandler' walnut (Juglans regia) on 'Northern California Black' (Juglans hindsii) and 'Paradox' (Juglans hindsii × Juglans regia) rootstocks were irrigated to achieve two levels of regulated deficit irrigation (RDI) in 2002 through 2005. The RDI strategy was to maintain high midday stem water potential (MSWP) early in the season (to favor shoot growth and nut size) and then gradually lower it until harvest. In a fully irrigated control, MSWP was maintained at -0.3 to -0.6 MPa throughout the growing season. In mild and moderate RDI treatments, MSWP was maintained at -0.3 MPa to -0.6 MPa early in the season and later lowered to -0.7 to -0.9 MPa or -0.9 to -1.1 MPa, respectively, by harvest. Nut load, total and edible yield, and the percentage of large, sound nuts were significantly affected by rootstock and irrigation treatment. In general, trees on 'Paradox' outperformed trees on 'Northern California Black' in all irrigation treatments, producing 2.0, 1.9, and 1.6 tonne more nuts per hectare, on average, under control and mild and moderate RDI conditions, respectively. On average, nut load on 'Paradox' was reduced by 19 and 30%, respectively, under mild and moderate water RDI conditions, while nut load on ‘Northern California Black’ was reduced by 28 and 38%, respectively. | |
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