Espacement studies on unirrigated grafted Pinot noir (Vitis vinifera L.)

Archer, Eben (1990)

Dissertation (Ph. D. Agric.) -- University of Stellenbosch, 1990.

Thesis

ENGLISH ABSTRACT: The effect of vine spacing on root distribution, plant and soil water status, some physiological aspects as well as vegetative and reproductive growth of Vitis vinifera L. cv. Pinot noir, grafted onto 99 Richter (Vitis Berandieri var. Las Sorres x Vitis rupestris var. du Lot) was investigated. Vine spacings used were 1,0 m x 0 .5 m, 1,0 m x 1,0 m, 2,0 m x 1,0 m, 2,0 m x 2,0 m, 3,0 m x 1,5 m, and 3,0 m x 3,0 m. This trial was conducted on a medium potential soil without irrigation in the Stellenbosch district. Root density was directly affected by vine spacing and it increased and decreased with closer and wider spacing respectively. The larger contact surface between roots and soil in the case of closer spaced vines, increased the utilization of soil water and nutrients. This increased depletion of soil water, induced water stress earlier in the growth season with the result of a timely arrestment of shoot growth. This phenomenon brought about advantageous characteristious in canopy density and canopy microclimate. Vine spacing also affected cordon length per vine as well as total cordon length per hectare, thus affecting the distribution and orientation of the canopy. Closely spaced vines induced shorter cordons per vine, but the total cordon length per hectare was higher than that of widely spaced vines. Although a smaller crop was produced per vine in the case of closer spacings, the total yield per hectare was higher than in the case of wider spewed vines. In addition, a better potential for bunch nutrition was ensured by a higher leaf surface : fruit mass ratio in the case of closer spaced vines. The low canopy densities of closer spaced vines, together with a better water-supply early in the season (bud break to pea size) ensured a higher physiological activity than in the case of wider spaced vines. As the season progressed, however, this situation was reversed so that the shoot elongation of closer spaced vines ceased before that of wider spaced vines. This phenomenon was advantageous for bunch nutrition, affecting both grape composition and wine quality. The subterranean and above-ground changes brought about by closer vine spacing augmented both yield and quality. A better wine quality was obtained through a higher sugar concentration, lower acid concentration and better colour of the grapes. A higher yield per hectare stemmed from an increase in total cordon length per hectare. These results were realized for a medium potential soil without irrigation. More luxurious conditions will probably induce more vegetative growth, necessitating wider in-row vine spacing for the best yield and quality. The ideal vine spacing for a given locality is dictated by soil potential, rootstock and scion cultivar and cultivation practices such as irrigation and fertilization. It is probably wrong to standardise vine spacing for all vineyards on a specific farm.

AFRIKAANSE OPSOMMING: Die invloed van stokspasiëring op wortelverspreiding, plant- en grondwaterstatus, sommige fisiologiese aspekte asook vegetatiewe- en reproduktiewe groei van die wingerdstok, Vitis vinifera L. cv. Pinot noir, geënt op 99 Richter (Vitis Berlandieri var. Las Sorres x Vitis rupestris var. du Lot), is ondersoek. Stokspasiërings van 1,0 m x 0,5 m, 1,0 m x 1,0 m, 2,0 m x 1,0 m, 2,0 m x 2,0 m, 3,0 m x 1,5 m en 3,0 m x 3,0 m is gebruik. Die studie is op 'n medium potensiaal grond in die Stellenboschdistrik uitgevoer en geen besproeiing is toegedien nie. Worteldigtheid is direk deur spasiëring van stokke beïnvloed. Nouer spasiërings het worteldigtheid verhoog, terwyl wyer spasiërings dit verlaag het. Hoe grater die totale kontakoppervlakte tussen gronddeeltjies en wortels was, hoe beter is water en voedingatowwe benut. Die verbeterde wateropname wat met hoër worteldigtheid verkry is, het meegebring dat grondwaterspanningstoestande gouer gedurende die groeiseisoen by nouer gespasieerde as by wyer gespasieerde stokke ingetree het. Hierdeur is waterspanningstoestande in die stokke geïnduseer wat onder die droëlandtoestande van hierdie proef 'n groter onderdrukkende invloed op die lootgroei van nouer as die van wyer gespasieerde stokke gehad het. 'n Onderdrukkende invloed op lootgroei het voordelige eienskappe vir lowerdigtheid en gepaardgaande lowermikroklimaat ingehou. Stokspasiëring het die kordonlengte per stok sowel as die kordonlengte per hektaar en sodoende ook die rangskikking en verspreiding van die lower beïnvloed. Hoe nouer die spasiëring, hoe kleiner was die kordonlengte per stok, maar hoe groter was dit per hektaar. Alhoewel daar dus minder druiwe per stok geprodueeer was, was die opbrengs per hektaar groter by nouer as by wyer gespasieerde stokke. Die blaaroppervlakte : vrugmassa verhouding was groter by nouer as by wyer gespasieerde stokke en dit het die potensiaal vir beter trosvoeding geskep. Weens beter watervoorsiening gedurende die vroeë deel van die seisoen (bot tot ertjiekorrelstadium), sowel as minder digte lower, was die nouer gespasieerde stokke fisiologies meer aktief as die wyer gespasieerde stokke. Soos die seisoen egter gevorder het, het 'n groter waterspanning in die nouer gespasieerde stokke ontwikkel wat 'n vroeër beeïndiging van lootgroei as in geval van wyer gespasieerde stokke bewerkstellig het. Sodoende is die kompetisie tussen lootgroeipunte en rypwordende trosse verhoed tot voordeel van beter trosvoeding. Alhoewel die blare van nouer gespasieerde stokke gedurende die laaste deel van die groeiseisoen fisiologies minder aktief was as dié van wyer gespasieerde stokke, is fotosintetiese produkte waarskynlik hoofsaaklik vir trosvoeding benut. Die onder- en bogrondee veranderinge wat deur nouer spasiëring by wingerdstokke meegebring word, het ender die toeetande van hierdie proef, veroorsaak dat beide opbrengs en wyngehalte verhoog kon word. Die verbetering in wyngehalte is teweeg gebring deur hoër suikerkonsentrasie, laer suurkonsentrasie en beter kleur van die druiwe. Die opbrengs per eenheidsgrondoppervlakte is verhoog deurdat nouer stokspasiëring die totale kordonlengte per hektaar verhoog het. Hierdie resultate is behaal vir 'n medium potensiaal grond sonder besproeiing. Gunstiger toestande vir vegetatiewe groei sou heelwaarskynlik daartoe gelei het dat bater resultate by wyer as by nouer stokspasiëring behaal word. Die ideale stokspasiëring vir 'n spesifieke lokaliteit word deur grondpotensiaal, onder- en bostokcultivar en produksiepraktyke soos bemesting en besproeiing bepaal. Dit is dus waarskynlik verkeerd om vir alle wingerdblokke op 'n plaas 'n uniforme stokspasiëring daar te stel.

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