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Molybdenum experiments: In Australia young Merlot vines sometimes suffer from vegetative disorders such as slow, zigzagged growth and leaf distortion. Merlot is also particularly known as a low- and inconsistent-yielding grape variety. Previous research showed that when foliar applications of molybdenum (Mo) were applied to Merlot vines the vegetative symptoms improved. More recently, when sodium molybdate was applied to Mo-deficient Merlot, yield improved; a function of increased bunch weight brought about by bigger berries. It has also been reported that at high concentrations, molybdenum might be detrimental to yield. Experiments were conducted on own-rooted Merlot (clone D3V14) vines in commercial vineyards in the Adelaide Hills (Hills) and at McLaren Vale, South Australia. Effects of molybdenum deficiency on the vegetative growth and yield of Vitis vinifera cv. Merlot: The aims of the current study were to: a) elucidate the mechanism by which molybdenum affects yield of Merlot; b) to monitor the effects of Mo-treatment on the balance between vine reproductive and vegetative growth; c) to monitor the residual effects of Mo-treatment on growth and yield of Merlot and; d) to determine whether high concentrations of molybdenum are detrimental to yield. Three rates of sodium molybdate were applied to vines in springtime (control = 0g, rate 1 = 0.101g and rate 2 = 0.202g sodium molybdate per vine). Vine molybdenum status was measured prior to treatment and again at flowering time using petiole, shoot tip and inflorescence analysis. The effects on vegetative growth were monitored at veraison, during dormancy and at budburst in the seasons following Mo-treatment. At flowering time, pollen vitality, pollen tube growth and flower structure were examined. Bunch number per vine, fruitset, berry weight and berry composition were measured at harvest. In the Hills, the controls had adequate molybdenum however, at McLaren Vale petiolar molybdenum concentration fell within the suggested deficiency range of 0.05-0.09 mg/kg in the petioles at flowering time. No visual symptoms of Mo-deficiency were observed on the experimental vines. At McLaren Vale, Mo-treatment reduced pruning weight and improved vine balance. Mo-treated vines in the Hills and at McLaren Vale were affected by delayed budburst in the season following Mo-treatment irrespective of their Mo-status. However, no seasonal carryover of molybdenum could be detected in tissue analysis at flowering time. Juice total soluble solids, pH and titratable acidity were not affected by Mo-treatment at McLaren Vale or in the Hills. However, juice from Mo-treated vines in the Hills had a significantly higher concentration of molybdenum than the controls. At McLaren Vale there was no significant difference in juice molybdenum concentration between treatments. In the Hills, yield was not affected by Mo-treatment. However, Mo-treated vines at McLaren Vale had significantly higher yields (approximately double) than the Mo-deficient controls. Bunch number per vine was not affected by Mo-treatment, either in the year that treatments were applied or in the following season. However, bunches from Mo-treated vines had significantly better fruitset resulting in more berries per bunch. Berry weight was affected by Mo-treatment in one season only. Yield was not detrimentally affected on vines that received the higher rate of sodium molybdate. In the Hills, Mo-treatment did not affect pollen numbers, pollen vitality or pollen tube growth. At McLaren Vale, where the controls were Mo-deficient, pollen vitality was not affected by Mo-treatment. However, pollen tube growth was significantly enhanced by Mo-treatment. Significantly more pollen tubes penetrated the ovules from Mo-treated vines and a higher proportion of ovaries had at least one penetrated ovule. Structural observations revealed that a significantly higher proportion of ovules from Mo-deficient vines were defective. The absence of an embryo sac in those ovules is probably the cause of pollen tube growth inhibition and subsequent poor fruitset. Effects of mode of pollination on yield of Merlot and the interacting effects of sodium molybdate sprays: Pollination experiments were conducted on field-grown own-rooted Merlot (clone D3V14) vines in commercial vineyards in the Adelaide Hills and at McLaren Vale in 2003-04 and in 2004-05. Inflorescences were supplied with supplementary Merlot pollen (self-pollination), with pollen from another variety (cross-pollination) or they were left to pollinate naturally (open pollination). In the Hills, mode of pollination did not affect fruitset or berry weight. In 2003-04 fruitset increased significantly at McLaren Vale when inflorescences were cross-pollinated with Semillon. Applying supplementary Merlot pollen also tended to improve fruitset, however none of the treatments affected berry weight. In 2004-05 there was no significant difference between treatments. These results indicate that Merlot may be a poor producer of pollen and may suffer from self-incompatibility. Given the significant improvements in yield gained by spring foliar applications of sodium molybdate to Mo-deficient Merlot vines, in 2005-06 a reciprocal experiment was conducted to separate the effects of Mo-treatment and mode of pollination on the male and female flower parts. The aims of this experiment were to: a) determine whether the male or female reproductive organs are more important in determining the success of fruitset of Merlot and; b) determine which remedial measure, Mo-treatment or pollination, is more effective at overcoming poor fruitset. Supplementary pollination treatments—cross-pollination (Semillon); self-pollination (Mo-deficient pollen); self-pollination (Mo-treated pollen) and; open-pollination—were applied to Mo-treated and Mo-deficient vines. Cross-pollinating Mo-deficient vines with Semillon significantly improved fruitset of Merlot compared to other pollination treatments on those vines, however applying molybdenum to the vines in springtime was more effective at improving fruitset. Within the Mo-treated vines the effects of supplementary pollination on fruitset were not thought to be of any practical significance. The results of this experiment provide further evidence that Mo-deficiency affects the female flower parts more than the male reproductive organs of Merlot. The occurrence of ‘star’ flowers in Australia: In 2003 faulty flowers were discovered on Canada Muscat grown in the Coombe Vineyard at the University of Adelaide’s Waite Campus. The Canada Muscat flowers opened from the top in ‘star’ formation in contrast to normal grape flowers, which shed the calyptra from its base. Star flowers were reported in French literature in the late 1800s. They were reported to as a symptom of a ‘disease’ that caused ‘coulure’, the cure for which was vine removal. The current report is the first known report of star flowers occurring in Australia. Through dissemination of the news of this discovery, several star flower variants were found in other varieties in South Australia. The association of star flowers with poor berry development and the frequency of the occurrence of star flowers suggest that this flower aberration may be affecting yield to a greater extent than previously recognised. This study provides a detailed description of two types of star flowers: those that occur in response to environmental conditions and those that occur every season. Other star flower variants are also documented. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1280856 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2007

Molybdenum experiments: In Australia young Merlot vines sometimes suffer from vegetative disorders such as slow, zigzagged growth and leaf distortion. Merlot is also particularly known as a low- and inconsistent-yielding grape variety. Previous research showed that when foliar applications of molybdenum (Mo) were applied to Merlot vines the vegetative symptoms improved. More recently, when sodium molybdate was applied to Mo-deficient Merlot, yield improved; a function of increased bunch weight brought about by bigger berries. It has also been reported that at high concentrations, molybdenum might be detrimental to yield. Experiments were conducted on own-rooted Merlot (clone D3V14) vines in commercial vineyards in the Adelaide Hills (Hills) and at McLaren Vale, South Australia. Effects of molybdenum deficiency on the vegetative growth and yield of Vitis vinifera cv. Merlot: The aims of the current study were to: a) elucidate the mechanism by which molybdenum affects yield of Merlot; b) to monitor the effects of Mo-treatment on the balance between vine reproductive and vegetative growth; c) to monitor the residual effects of Mo-treatment on growth and yield of Merlot and; d) to determine whether high concentrations of molybdenum are detrimental to yield. Three rates of sodium molybdate were applied to vines in springtime (control = 0g, rate 1 = 0.101g and rate 2 = 0.202g sodium molybdate per vine). Vine molybdenum status was measured prior to treatment and again at flowering time using petiole, shoot tip and inflorescence analysis. The effects on vegetative growth were monitored at veraison, during dormancy and at budburst in the seasons following Mo-treatment. At flowering time, pollen vitality, pollen tube growth and flower structure were examined. Bunch number per vine, fruitset, berry weight and berry composition were measured at harvest. In the Hills, the controls had adequate molybdenum however, at McLaren Vale petiolar molybdenum concentration fell within the suggested deficiency range of 0.05-0.09 mg/kg in the petioles at flowering time. No visual symptoms of Mo-deficiency were observed on the experimental vines. At McLaren Vale, Mo-treatment reduced pruning weight and improved vine balance. Mo-treated vines in the Hills and at McLaren Vale were affected by delayed budburst in the season following Mo-treatment irrespective of their Mo-status. However, no seasonal carryover of molybdenum could be detected in tissue analysis at flowering time. Juice total soluble solids, pH and titratable acidity were not affected by Mo-treatment at McLaren Vale or in the Hills. However, juice from Mo-treated vines in the Hills had a significantly higher concentration of molybdenum than the controls. At McLaren Vale there was no significant difference in juice molybdenum concentration between treatments. In the Hills, yield was not affected by Mo-treatment. However, Mo-treated vines at McLaren Vale had significantly higher yields (approximately double) than the Mo-deficient controls. Bunch number per vine was not affected by Mo-treatment, either in the year that treatments were applied or in the following season. However, bunches from Mo-treated vines had significantly better fruitset resulting in more berries per bunch. Berry weight was affected by Mo-treatment in one season only. Yield was not detrimentally affected on vines that received the higher rate of sodium molybdate. In the Hills, Mo-treatment did not affect pollen numbers, pollen vitality or pollen tube growth. At McLaren Vale, where the controls were Mo-deficient, pollen vitality was not affected by Mo-treatment. However, pollen tube growth was significantly enhanced by Mo-treatment. Significantly more pollen tubes penetrated the ovules from Mo-treated vines and a higher proportion of ovaries had at least one penetrated ovule. Structural observations revealed that a significantly higher proportion of ovules from Mo-deficient vines were defective. The absence of an embryo sac in those ovules is probably the cause of pollen tube growth inhibition and subsequent poor fruitset. Effects of mode of pollination on yield of Merlot and the interacting effects of sodium molybdate sprays: Pollination experiments were conducted on field-grown own-rooted Merlot (clone D3V14) vines in commercial vineyards in the Adelaide Hills and at McLaren Vale in 2003-04 and in 2004-05. Inflorescences were supplied with supplementary Merlot pollen (self-pollination), with pollen from another variety (cross-pollination) or they were left to pollinate naturally (open pollination). In the Hills, mode of pollination did not affect fruitset or berry weight. In 2003-04 fruitset increased significantly at McLaren Vale when inflorescences were cross-pollinated with Semillon. Applying supplementary Merlot pollen also tended to improve fruitset, however none of the treatments affected berry weight. In 2004-05 there was no significant difference between treatments. These results indicate that Merlot may be a poor producer of pollen and may suffer from self-incompatibility. Given the significant improvements in yield gained by spring foliar applications of sodium molybdate to Mo-deficient Merlot vines, in 2005-06 a reciprocal experiment was conducted to separate the effects of Mo-treatment and mode of pollination on the male and female flower parts. The aims of this experiment were to: a) determine whether the male or female reproductive organs are more important in determining the success of fruitset of Merlot and; b) determine which remedial measure, Mo-treatment or pollination, is more effective at overcoming poor fruitset. Supplementary pollination treatments—cross-pollination (Semillon); self-pollination (Mo-deficient pollen); self-pollination (Mo-treated pollen) and; open-pollination—were applied to Mo-treated and Mo-deficient vines. Cross-pollinating Mo-deficient vines with Semillon significantly improved fruitset of Merlot compared to other pollination treatments on those vines, however applying molybdenum to the vines in springtime was more effective at improving fruitset. Within the Mo-treated vines the effects of supplementary pollination on fruitset were not thought to be of any practical significance. The results of this experiment provide further evidence that Mo-deficiency affects the female flower parts more than the male reproductive organs of Merlot. The occurrence of ‘star’ flowers in Australia: In 2003 faulty flowers were discovered on Canada Muscat grown in the Coombe Vineyard at the University of Adelaide’s Waite Campus. The Canada Muscat flowers opened from the top in ‘star’ formation in contrast to normal grape flowers, which shed the calyptra from its base. Star flowers were reported in French literature in the late 1800s. They were reported to as a symptom of a ‘disease’ that caused ‘coulure’, the cure for which was vine removal. The current report is the first known report of star flowers occurring in Australia. Through dissemination of the news of this discovery, several star flower variants were found in other varieties in South Australia. The association of star flowers with poor berry development and the frequency of the occurrence of star flowers suggest that this flower aberration may be affecting yield to a greater extent than previously recognised. This study provides a detailed description of two types of star flowers: those that occur in response to environmental conditions and those that occur every season. Other star flower variants are also documented. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1280856 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2007

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2018-02-21T13:43:00Z No. of bitstreams: 1 PGPV15MA185.pdf: 1457517 bytes, checksum: 4293d4dda1796f82f86a5921ddb2d618 (MD5) / Made available in DSpace on 2018-02-21T13:43:00Z (GMT). No. of bitstreams: 1 PGPV15MA185.pdf: 1457517 bytes, checksum: 4293d4dda1796f82f86a5921ddb2d618 (MD5) Previous issue date: 2015-10-29 / PROMOP / In years when conditions are unfavorable for pollination and when the intensity of flowering is small, you may need to improve the fruit set. The use of growth regulators can be a strategy to be adopted in order to ensure good fruit set. The Thidiazuron is a phenylurea with cytokinin action, when it is applied at low concentrations during cell division it can increase fruit set and fruit size. The aim of this study was to evaluate the effect of Thidiazuron concentration in fruit set and fruit quality of apple ‘Royal Gala’, grown in mild winter conditions. The experiment was arranged during cycles 2011/2012, 2012/2013 and 2013/2014 in Fraiburgo, SC, in the Royal Gala apple trees in Marubakaido rootstock M9 with filter. In all evaluation cycles the experimental design was a randomized block with factorial design (6x3x2) with six concentrations of TDZ, two application forms and three years of evaluation, composed of twelve treatments with six replications, the experimental unit was formed by one plant. The TDZ concentrations of each treatment were applied in two seasons. The first application was performed on pink bud stage (E2) and the second application in full bloom stage (F2). The variables: fruit set (%), return of flowering (%), number and weight of fruits per plant, average fruit bulk (g), average fruit length, average fruit diameter and length/diameter of the fruit (C/D), average number of seeds, caliber by classes: ≤135; and between 136-165 ≥180. Red coloration of the skin of the fruit were evaluated in three classes: percentage of fruits with a red color covering less than 50% of the surface; percentage of fruits with a red color covering 50% to 80% of the surface; and percentage of fruits with red color covering more than 80% of the whole surface. Were determined the mineral content of N, P, K, Ca, Mg and their relationship, flesh firmness, starch degradation and soluble solids content. The data were submitted to analysis of variance and the significant variables was performed the analysis of orthogonal contrasts. Significant data also were adjusted in the regression equations to evaluate the behavior of the variables with increasing concentration. We also used Pearson correlation analysis to check for possible relationships between the different attributes evaluated. The TDZ is effective even at low concentrations, and it increases production and fruit set of apple especially when there are unfavorable weather problems during pollination period. TDZ reduces the ripening of fruits. There is a reduction in the percentage of red color covering the skin of the fruit and number of seeds per fruit in plants that received the application of TDZ. The levels of minerals present in the flesh keeps within the sufficiency range independent of the concentration of TDZ applied / Em anos em que as condições forem desfavoráveis à polinização e quando a intensidade da floração for pequena, pode ser necessário melhorar a frutificação efetiva. A utilização de fitorreguladores pode ser uma estratégia a ser adotada a fim de garantir uma boa frutificação efetiva. O Tidiazurom é uma feniluréia com ação de citocinina que quando aplicado em baixas concentrações durante a divisão celular pode promover o aumento na frutificação efetiva e o tamanho dos frutos. O objetivo desse trabalho foi avaliar o efeito da concentração de tidiazurom na frutificação e qualidade de frutos de macieira ‘Royal Gala’, cultivadas em condições de inverno ameno. O experimento foi conduzido durante os ciclos 2011/2012, 2012/2013 e 2013/2014 em Fraiburgo, SC, em macieiras da cultivar Royal Gala em porta enxerto Marubakaido com filtro de M9. Em todos os ciclos de avaliação o delineamento experimental foi em blocos casualizados com esquema fatorial (6x3x2), com seis concentrações de TDZ, duas formas de aplicação e três anos de avaliação, composto por doze tratamentos com seis repetições, sendo a unidade experimental formada por uma planta. As concentrações de TDZ respectivas a cada tratamento foram aplicadas parceladamente em duas épocas. A primeira aplicação foi realizada no estádio de balão rosado (E2), e a segunda aplicação no estádio de plena floração (F2). Foram avaliadas as variáveis: frutificação efetiva (%), retorno de floração (%), número e massa de frutos por planta, massa fresca média de frutos (g), comprimento e diâmetro médio dos frutos e relação comprimento/diâmetro dos frutos (C/D), número médio de sementes, calibre por classes: ≤135; entre 136-165 e ≥180. Foi avaliado a coloração vermelha da epiderme dos frutos em três classes: porcentagem de frutos com coloração vermelha cobrindo menos de 50% da superfície do fruto; porcentagem de frutos com coloração vermelha cobrindo 50% a 80% da superfície do fruto; e porcentagem de frutos com coloração vermelha cobrindo mais de 80% da superfície do fruto. Foram determinados os teores minerais de N, P, K, Ca, Mg e suas relações da polpa fresca de frutos, firmeza de polpa, iodo-amido e conteúdo de sólidos solúveis totais (SST). Os dados obtidos foram submetidos à análise da variância e para as variáveis significativas foi realizada a análise de contrastes ortogonais. Os dados significativos também sofreram ajustes nas equações de regressão com a finalidade de avaliar o comportamento das variáveis com o aumento da concentração. Utilizou-se também a análise de correlação de Pearson para verificar possíveis relações existentes entre os diferentes atributos avaliados. O TDZ é efetivo, mesmo em baixas concentrações, no aumento da produção e frutificação efetiva de macieira sobretudo quando ocorrem problemas climáticos desfavoráveis à polinização. O TDZ retarda a maturação dos frutos. Há redução na porcentagem de coloração vermelha recobrindo a epiderme dos frutos e número de sementes por fruto nas plantas que receberam aplicação de TDZ. Os teores de minerais presentes na polpa mantem-se dentro da faixa de suficiência independente da concentração de TDZ aplicada

Made available in DSpace on 2014-08-20T13:25:43Z (GMT). No. of bitstreams: 1 Dissertacao_Michel_Aldrighi_Goncalves.pdf: 1516499 bytes, checksum: 9da5ae7039fd806dd67f130ae9fec997 (MD5) Previous issue date: 2011-03-02 / The present work aimed to evaluate and characterize the behavior of different peach genotypes submitted to variations of period and type of pruning, in the region of Pelotas, RS. The work was carried out in Pelotas, RS, in an experimental area belonging to Embrapa Clima Temperado (CPACT) during 2009 and 2010 seasons. Two experiments were done: the first one was comprised of a combination among three periods of pruning (Winter pruning WP; winter pruning plus summer pruning WSP; and summer pruning SP) and three genotypes (Cascata 805, Cascata 834 (BRS Kampai) and Cascata 952 (BRS Rubimel), resulting in nine distinct combinations. The second experiment consisted in three types of pruning (short pruning SP; long pruning LP; and no shoot topping NST) and two genotypes (Riograndense and Leonense), resulting in six treatments. In general, the chemical characteristics of the fruits are not affected by the different pruning period, as well as, the fruitset. BRS Rubimel did not show uniformity of yield in the following years when using the summer pruning; however, BRS Kampai had a good yield equilibrium at all pruning date tested. Trees pruned only in the winter period showed higher vigor whether compared to other studies. The different types of pruning directly affected the number of flowers and fruits, diameter and mean mass, and yield. The short pruning stimulates the growth of undesirable shoots, making unviable the summer pruning practice. In general, the variations of pruning type and period could be commercially used depending on the genotype studied. / Com o presente trabalho objetivou-se avaliar e caracterizar o comportamento de diferentes genótipos, submetidos a variações de época e tipo de poda na região de Pelotas, RS. O mesmo foi conduzido no município de Pelotas, RS, em uma área experimental pertencente a Embrapa Clima Temperado (CPACT), durante os anos de 2009 e 2010 e, composto de dois experimentos: o primeiro teve como tratamentos a combinação de três épocas de poda (Poda de inverno (PI), poda de inverno mais poda de verão (PIV) e poda de verão (PV)) e três genótipos (Cascata 805, Cascata 834 (BRS Kampai) e Cascata 952 (BRS Rubimel), resultando em nove combinações distintas; o segundo experimento os tratamentos foram compostos por três tipos de poda (Poda curta (PC), poda longa (PL) e poda sem desponte (PSD) e dois genótipos (Riograndense e Leonense), resultando em seis tratamentos. Em geral as características químicas dos frutos não são alteradas com as variações de época de poda estudadas, assim como a frutificação efetiva. BRS Rubimel não apresentou uniformidade produtiva com a sucessão de cultivos com poda apenas no período de verão, já a BRS Kampai teve um bom equilíbrio produtivo em todas as datas de podas testadas. Plantas podadas apenas no período de inverno apresentam maior vigor quando comparadas com as demais estudados. Já os diferentes tipos de poda influenciaram diretamente no número de flores e frutos, diâmetro e massa média, assim como na produtividade. A poda curta estimula o crescimento de ramificações indesejáveis tornando mais trabalhosa a prática da poda verde. De maneira geral as variações de tipo e época de poda podem ser utilizadas comercialmente dependendo do genótipo trabalhado.

Viticultural practices such as trunk girdling and shoot topping along with defoliation, shading and node number per vine treatments were used to alter the carbohydrate physiology of mature Chardonnay grapevines growing in the cool climate of Canterbury, New Zealand. The timing of vine defoliation in the season previous to fruiting decreased concentrations of over-wintering carbohydrate reserves (mostly starch) in both the trunks and roots of grapevines. Roots were particularly sensitive, with defoliation as early as 4 weeks after bloom in the previous season reducing starch concentrations to 1.5%Dwt at bud burst compared with 17%Dwt in non-defoliated vines. In contrast, partial vine defoliation as early as bloom in the previous season reduced root starch concentrations to 4-7%Dwt at bud burst compared with 15%Dwt in non-defoliated vines. Vine shading and trunk girdling treatments at bloom in the previous season, resulted in small reductions in root starch concentrations (16%Dwt) compared with non-shaded and non-girdled vines (19%Dwt), but shoot topping did not. Study across three growing seasons established that higher concentrations of over-wintering trunk and root carbohydrate reserves were associated with warmer and sunnier weather in the previous growing season. Individual shoot leaf removal at either the beginning or towards the end of the inflorescence initiation period, reduced shoot starch concentrations to 3-6%Dwt compared with 11 %Dwt for no leaf removal, such reductions persisted through to the following season. Shoot topping at the start of the initiation period had no effect on shoot carbohydrate accumulation, but trunk girdling temporarily increased shoot starch concentrations during the first 31 days after treatment. Reductions in over-wintering trunk and root carbohydrate reserves were associated with a reduction in inflorescences per shoot and flowers per inflorescence in the following season, the reduction as much as 50% compared with non carbohydrate stressed vines. While there were strong linear or curvilinear relationships between the concentration of starch in trunks and roots at bud burst and inflorescences per shoot and flowers per inflorescence, in case the of inflorescences per shoot, there was not an immediate cause and effect because inflorescences were initiated in the previous season. Individual shoot leaf removal during the inflorescence initiation period illustrated that leaf removal directly inhibited the initiation of inflorescences in latent buds. Shoot carbohydrate measurements showed a strong curvilinear relationship to the number of inflorescences per shoot, with a threshold starch concentration of 10-12%Dwt during the inflorescence initiation period required for a maximum number of inflorescences per shoot. Furthermore, examination of individual node positions emphasised the importance of the subtending leaf on the initiation of inflorescences within the latent bud. The number of inflorescences per shoot post bud burst was reduced on vines that were both carbohydrate reserve stressed (by previous season's defoliation) and had a high node (108) number retained per vine after winter pruning compared with little or no reduction in inflorescences per shoot on carbohydrate reserve stressed vines that had a low (20) node number per vine. The reduction in inflorescences per shoot on high node vines was associated with reduced carbohydrate reserves and reduced shoot vigour (thinner and lighter shoots). Flowers per inflorescence were reduced by as much 50% in response to lower overwintering carbohydrate reserves. Fewer flowers per inflorescence were attributed to a reduction in primary branching of the inflorescence and also a reduction in flowers per branch. Strong linear relationships between the concentrations of starch in trunks and roots and flowers per inflorescence indicate that the determination of flowers per inflorescence, unlike inflorescences per shoot, may be dependent on the level of overwintering carbohydrate reserves. This is most likely due to changes in branching of the inflorescence and individual flower formation occurring during the bud burst period. Per cent fruitset was not affected by reductions in carbohydrate reserves, so fewer inflorescences per shoot and flowers per inflorescence resulted in reduced vine yield. The findings of this thesis indicate that changes in the level of carbohydrate production and partitioning in response to a range of viticultural management practices and seasonal weather contribute to seasonal variation in grapevine flowering and yields in New Zealand's cool climate environment. The relationships between carbohydrate reserves and flowering illustrate the potential to use this information to predict grapevine flowering and forecast yields. The practical implications of this research illustrate that the viticulturist must manage grapevines not only for the current crop, but also for subsequent crops by maintaining sufficient carbohydrate reserves for balanced growth flowering and fruiting from season to season.