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Subject: search.filters.subject.Lycopersicon esculentum

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    Yield responses of tomato (Lycopersicon esculentum Mill.) to fruit thinning and plant spacing : a thesis presented in partial fufilment [sic] of the requirements for the degree of Master of Applied Science in Plant Science at Massey University
    (Massey University, 2002) Field, Stewart K
    Control of individual tomato (Lycopersicon esculentum Mill.) fruit weight during a crop cycle is of commercial benefit to improve marketable yield. To assess the main causes of variability in tomato fruit size, plant spacing and fruit thinning effects on fruit yield and individual fruit weight down the truss was examined. Three fresh market tomato cultivars, Alboran (Standard), Ophir (Beefsteak) and Cherita (Cherry) were grown, in New Zealand during winter and spring months of 2001, in a greenhouse with NFT at three plant densities (2.76, 3.67 and 4.59 plant per m 2 ). Each tomato cultivar was fruit thinned to three different levels (3, 4 and 5 fruit per truss for Alboran; 1, 2 and 3 fruit per truss for Ophir; 4, 8 and 12 fruit per truss for Cherita). Total fruit weight and fruit number were taken at each harvest for all treatments. At the low density (2.76 plants per m 2 ) individual fruit weights within each truss were taken for all fruit thinning treatments. A total soluble solid measurement was also taken during an August harvest. Alboran showed a significantly higher final fruit yield per surface area than Ophir and Cherita cultivars, indicating why Alboran is a standard cultivar. No difference in fruit yield or fruit number surface area was observed with both Alboran and Ophir cultivars as plant density increased. This was the result of flower and / or fruit abortion at the higher densities, due to low solar radiation levels observed under winter and spring conditions in this study. Cherita, although not significant, showed a trend of increasing fruit yield per surface area as plant density increased. The low solar radiation levels did not have as larger effect on flower and / or fruit abortion in Cherita. It had a lower fruit (sink) load and was able to support more fruit development with the low levels of photosynthetic assimilate produced under the low solar radiation levels. Larger mean fruit weights, in all three cultivars, were observed with more fruit thinning due to increased photosynthetic assimilate being available to the remaining fruit. No difference in fruit yield per surface area was observed with both Alboran or Ophir cultivars as more fruit were left on the truss, which was due to the smaller mean fruit weight and a greater proportion of flower and / or fruit abortion caused by the high fruit load with low solar radiation levels. However thinning Cherita to 4 fruit per truss did produce significantly lower yields per surface area compared with 8 and 12 fruit per truss. Individual fruit weight down the truss, of all three cultivars, reduced in size by a constant factor or slope. A slope of -13 g / fruit position was observed for Alboran, which was flatter than that of Ophir (-17 g / fruit position) and steeper than that of Cherita (-0.15 to -0.60 g / fruit position). The number of fruit on the truss did not affect the slope of Alboran and Ophir cultivars, while thinning Cherita to 4 fruit per truss produced a significantly steeper slope (-0.60 g / fruit position) than 8 and 12 fruit per truss (0.25 g / fruit position). More fruit present on a truss produced smaller proximal (first) fruit, thus reducing the size of the remaining fruit on the truss proportionately. Individual trusses within Cherita were also shown to have a constant slope of fruit size down the truss. These results suggest that plant density and fruit thinning can be used to produce more fruit within the desired marketable fruit size range all year round. However a greater understanding of plant density and fruit thinning interactions during different growing seasons must first be achieved.
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    Studies on the growth and development of the tomato (Lycopersicon esculentum Mill.) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University
    (Massey University, 1974) Fisher, Keith James
    During the propagation of tomato plants a high and a low level of nitrogen was applied in factorial combination before and after initiation of truss 1. The high level of nitrogen prior to initiation produced earlier flowering and an increased yield in truss 1. It was suggested that a contributing factor to the latter response was that, where a change in nitrogen level was involved, the change from high nitrogen to low nitrogen produced a more productive plant response than when the sequence of applications was reversed. Flower number and earliness of flowering of certain trusses was increased by the high level of nitrogen applied after initiation. Initially the plants grew faster and cropped earlier in response to high nitrogen, but there were no differences in either the final amount of growth or the final crop. The response of the plants to a change in nitrogen level suggested that some of the increase in yield due to exposure of young plants to cold temperatures, may be due to the change in temperature level. Warm and cold temperatures were therefore applied in factorial comination before flower initiation (9 nights) and for a subsequent period (14 nights) which included the flower initiation stage, with single-truss tomato plants. Cold temperatures during both stages increased yield and number of fruit and decreased mean fruit weight. The early treatment was the most effective. It was suggested that low temperatures produced an enhanced supply of assimilates to the apex, which then initiated more flowers and that cold temperatures appeared to influence yield solely due to its effect on flower number. Shoot growth was reduced as yield increased and it was suggested that competition occurs for assimilates between the leaves and fruit. The remaining investigations were devoted to the relationship between vegetative and reproductive growth (source sink relationship) in the tomato plant. By the use of leaf removal treatments a study on the importance of the amount and position of leaf tissue on the yield of single-truss tomato was carried out. A close positive relationship was shown to exist between leaf dry weight and yield, while leaf position did not appear to be important. The leaf and root tissues were shown to be in competition with the reproductive tissues for dry matter. The nitrogen experiment indicated that competition occured between fruit trusses for assimilates. By allowing plants to develop different numbers of trusses and then examining the effects of these treatments on the yield of a particular truss, competition effects between trusses were shown to exist with all trusses except truss 1. The final investigation was designed to demonstrate that the yield of truss 1 could be reduced by competition for assimilates. The treatments consisted of 3 leaf levels, 2 pollination levels and 3 truss numbers in factorial combination. Competion effects reduced the yield of truss 1 and it was shown that such effects were influenced by the level of sink strength. Total yield was increased by increases in leaf level when sink strength was high and by additional trusses or extra pollination when the amount of leaf tissue was adequate. Evidence was presented in the last three studies that economic yield in the tomato plant can be limited simultaneously by lack of both source and sink strength. The studies on competition effects between trusses indicated that the net assimilation rate in the tomato plant can be depressed by lack of sink strength. Aspects of the source sink relationship in the tomato plant are discussed.
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    Shoot-root allometry and growth of nashi and tomato : the effects of budding, gibberellins and cytokinins : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Horticultural Science at Massey University
    (Massey University, 1991) Thuantavee, Sureerat
    Growth of the root and the shoot systems of plants is generally, positively correlated, although the mechanism(s) controlling such relationships is not well understood. A series of experiments were carried out on young nashi trees (Pyrus serotina) and tomatoes (Lycopersicon esculentum Mill.) to explore this homeostatic phenomenon. Two nashi cultivars, Hosui and Nijiseiki, were budded on to each of three clonal rootstocks, which differed in vigour (scion-budded trees). Buds from each rootstock was also budded on their own roots (rootstock trees). Growth, measured by individual organ and total plant dry weight, leaf attributes (leaf area, leaf number and leaf size) and root attributes (root length, root number and root volume) over two years after budding, indicated that scion-budded trees were markedly smaller than rootstock trees, irrespective of rootstock vigour. The imbalance of shoot-root ratio occurred following pruning after bud take; this remained in rootstock trees for one year but persisted for two years in scion budded trees. Vigour of all rootstocks appeared to diminish with time and final tree size was not well related to initial rootstock vigour. Neither rootstock nor scion morphological characteristics appeared to be changed by the partner, although presence of the cultivar bud on rootstocks delayed commencement of root activity in early spring. These results indicate that two-year-old (scion budded growth) nashi trees are not appropriate material for studying allometric relationship. Plant growth regulators, gibberellins and cytokinins, were applied to 6- and 5-week-old tomato seedlings, respectively, in three separate aeroponic experiments. Gibberellic acid was sprayed twice to the shoot (at 2.9 X10-5 M), while root application was achieved by incorporating GA3 into the nutrient solution (cone. 5.8 X10-5 and 2.9 X10-4 M). Compared to the control, stem elongation, stem dry weight and stem weight ratio (SWR) was increased while root attributes (dry weight and root weight ratio (RWR)), leaf attributes (leaf area, leaf area ratio and leaf dry weight), and consequently total plant dry weight were reduced in GA3 treated plants. Gibberellic acid promoted apical dominance. Shoot applied GA3 was quantitatively more effective than root application, suggesting that the organ in which physiologically active GA(s) originate may be an important component of plant response to environments. In addition, GA3 effects were additive as indicated by the increasing difference with time in SWR and shoot-root ratio. The increased SWR and reduced leaf weight ratio (LWR) were responsible for an increase in the allometric value between stem and root dry weight (kS), and a reduction in the allometric value between leaf and root dry weight (kL), respectively. However, allometric value between shoot and root dry weight (kT) was unaltered by GA3. These results suggest no feedback mechanism of de novo GA synthesis occurred, and indicate that GA has no role in regulation of shoot-root allometry. A synthetic cytokinin, benzylaminopurine (BA), was applied to roots at 2.2 X10-8, 2.2 X10-7 and 2.2 X10-6 M. The control gave an intermediate response in all parameters measured, compared to the enhanced response at 2.2 X10-8 M BA and the inhibitory response at other BA concentrations. This suggested that BA supplemented, and had a similar effect to, endogenous cytokinins. Benzylaminopurine initially or transiently stimulated shoot and leaf primordia and thus released buds from apical dominance, leading to an increase in leaf attributes (leaf number, leaf area, leaf dry weight and leaf weight ratio (LWR)), increased shoot-root ratio and reduced RWR. Benzylaminopurine had no effect on stem attributes (stem elongation, stem dry weight and SWR). There were, however, no changes induced in kL and kT. It is suggested that cytokinins participate in the homeostatic mechanism regulating plant growth allometry. A model in which both gibberellins and cytokinins integrate to affect plant growth via allometric relationships is proposed. The usefulness of allometric studies to detect and analyse dynamic changes of organs and plant productivity in response to environment, as well as explain mechanisms regulating shoot-root equilibrium is strongly endorsed by this study.