ISHS Acta Horticulturae 640: XXVI International Horticultural Congress: Viticulture - Living with Limitations
RELATION OF APPLIED CROP STRESS TO INFLORESCENCE DEVELOPMENT, SHOOT GROWTH CHARACTERISTICS, AND CANE STARCH RESERVES IN 'CONCORD' GRAPEVINE |
| Author: | M.C. Goffinet |
| Keywords: | carbohydrate, defruiting, defoliation, fruit set, phloem, primary bud, xylem |
| Abstract:
‘Concord’ (Vitis labruscana) vines were adjusted to a range of crop stress relative to leaf area. Treatments were balance-pruning (BP) and 3 minimal-pruned (MP) treatments stressed either by defoliation in late July (MP-defol), unstressed by defruiting 30 days post bloom (MP-defrt), or untreated (MP-check). Winter buds and their emergent shoots were collected with their cane internodes through leaf fall for three years. Flower development and fruit set were evaluated with regard to shoot length, leaf production, mature leaf number, and shoot leaf area. Canes were analyzed for carbohydrate (CHO) content. As crop stress increased by increasing shoot numbers and by eliminating leaf area, the above shoot growth characteristics became more depressed. BP vines had greatest shoot growth, leaf production rate, leaf maturation rate, and greatest leaf area per shoot, while MP-defol vines had the least. Of MP treatments, MP-defrt vines consistently fared best. By bloom, flower number in clusters of MP-defol vines was only half that of clusters in any other treatment. No matter the prior crop stress, starch reserves dissipated rapidly between bud break and bloom in canes, and then increased post-bloom as new leaves began supplying a pool of new CHO. Overwintered starch reserves were least in the MP-defol treatment, most in BP, and intermediate in MP-defrt and MP-check treatments. This pattern also held for late-season restoration of reserve starch, so the extremely overcropped MP-defol vines ran the entire season on low reserves and later generated only low reserves for next season. | |
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