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    The effect of coir particle size on yield of greenhouse tomatoes (Lycopersicon esculentum Mil.) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science (Horticultural Science) at Massey University, Turitea, New Zealand
    (Massey University, 2012) Duggan-Jones, Damian
    Coir is a relatively new growing media, and little information is known of the relationship between particle size and particle size distribution on crop productivity. Particle size significantly affects the physical properties of coir, particularly the air-water relationships. The objectives are (1) to investigate the relationship water holding capacity has on total yield, fruit number and mean fruit weight of tomato (2) determine whether growth analysis could be used to test treatments prior to full scale growth trials in terms of predicting yields based on small sample sets of limited duration. Two yield trials, summer and winter trials, was designed to compare the yield of a tomato (Lycopersicum esculentum) crop grown in coir using a range of particle sizes, while a plant growth analysis was used to compare RGR, LAR, and NAR. Two coir sources were used throughout the trials. One source consisted of seven treatments based on combinations of small (S), medium (M) and large (L) size grade particles. The second source consisted of two ungraded coir products, P1 and P3. Two irrigation (low and high) frequencies were used. The seven treatments were based on particle size with differences in WHC (water holding capacity). A bioassay was used to compare tomato yield and RGR. The physical properties, governed by particle size, have an effect on tomato yield. The average yield for the winter yield trial was 2.14 and 2.38 kg per plant for SG and HK data while the average yield for the summer yield trial was 7.92 and 7.69 kg per plant. An increasing linear relationship exists between WHC and fruit yield per plant, as treatments increase in WHC so do their fruit yield per plant. A relationship was also found between the bioassay and tomato yield trial. Similar to the tomato yield trial, as WHC increased so did the RGR. The relationship between WHC and RGR may have commercial implications for both soilless media manufacturers and growers who require specific physical properties in terms of water and air availability for particular crop types.
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    Transplanting studies with processing tomato (Lycopersicon esculentum Mill.) and green sprouting broccoli (Brassica oleracea L. var. italica Plenck) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Horticulture at Massey University
    (Massey University, 1992) Davis, Stuart Ian
    Field experiments were conducted to evaluate the performance of module-raised and bare-root seedling transplants of determinate tomato and green sprouting broccoli. In the tomato experiment, seedlings raised in 36 cm3 modules in a greenhouse and bare-root transplants raised in a seed-bed under cold frames were transplanted into a field at Hastings in October 1983. In the broccoli study, seedlings were raised in 36 cm3 modules and in seed-beds in a field and in a greenhouse and then transplanted into a field at Massey University in November 1984. Tomato plants established as module-raised transplants had higher shoot and root dry weights 35 days after transplanting, and flowered 2 weeks earlier than plants established as bare-root transplants. A series of nine destructive harvests, at approximately weekly intervals, revealed similar patterns of red fruit yield with time for plants established from the two types of transplant. The loss of the early growth advantage of the plants established from module-raised transplants was not explained by conversion to a thermal time scale. Further research is required to determine if the sharp peak of red fruit yield with time recorded in this experiment is typical for tomato crops grown in New Zealand. The growth of broccoli plants over the first 32 days from transplanting was recorded from unreplicated plots. From the results of a series of dry weight harvests, it was estimated that, 18 days after transplanting, broccoli plants established as module-raised transplants produced in the field and in the greenhouse were 7 and 5 days, respectively, more advanced in terms of shoot dry weight than plants established from the corresponding bare-root treatments. Plants established from module-raised transplants initiated terminal inflorescences earlier than plants established from the corresponding bare-root transplants. These results were attributed to reduced root disturbance at transplanting for the module-raised transplants. The effects of transplant type on the maturity and yield of broccoli were evaluated using a series of selective harvests in a replicated experiment. In the case of the field-raised transplants, the more rapid establishment and earlier initiation of the terminal head of plants established from module-raised transplants was reflected in earlier maturity at harvest. There was no difference in the time to maturity of module-raised and bare-root transplants raised in the greenhouse. The patterns of post-transplanting growth and maturity of plants raised in modules in the greenhouse and transplanted with or without growing medium around the roots were very similar. This indicated that reduced root disturbance was a more important factor in the rapid establishment of module-raised transplants than the presence of a reserve of water in the growing medium of the module. These results with tomato and broccoli illustrate that earlier and more uniform establishment of module-raised transplants may not always be reflected in earlier and more uniform crop maturity, due to the effects of environmental factors and inter-plant competition later in the growth of the crop. It is suggested that differences in crop maturity and yield between plants established from module-raised and bare-root transplants would have been more marked under more stressful field establishment conditions.
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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.
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    Root restriction and root-shoot relationships in tomato (Lycopersicon esculentum Mill.) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Horticultural Science at Massey University
    (Massey University, 1995) MacKay, Bruce R.; MacKay, Bruce R.
    The potential for controlling plant growth and productivity by manipulating root growth and development has not been realised because of a lack of understanding of how root growth influences shoot growth. Until such responses are understood, matching container design and volume to desired plant output will continue to be based solely on anecdotal evidence. A series of experiments were conducted to explore the role of physical root restriction on the vegetative growth and development of tomato (Lycopersicon esculentum Mill. 'Moneymaker'). Concurrent with these experiments, a statistical model was developed for non-destructively estimating leaf area, cluster analysis was adapted to improve experimental precision, and an improved form of growth analysis developed. Additionally, a review of oxygen and major nutrient uptake rates by tomato established the operational parameters of a hydroponic system developed specifically for the study. Rooted tomato cuttings were grown in 0.025 or 10 litre (control) containers in the hydroponic system. After 31 days in 0.025 litre containers, plants were de-restricted into either 0.05 or 10 litre containers, or retained in the 0.025 litre containers. Plants with physically restricted root systems had lower total plant biomass and total leaf area, were shorter in both height and total root length, and had fewer roots, leaves, and lateral shoots than unrestricted plants. Restriction reduced root number after 31 days, but reductions in root length and dry biomass did not occur until after 45 days. Leaf dry biomass was reduced in restricted plants after 45 days; reductions in stem height, leaf area, number and total dry biomass) were apparent after 67 days. Short periods (31 days) of root restriction had long term (67-99 days) effects on leaf growth. Leaf expansion was more sensitive than leaf biomass accumulation to root restriction. A strong linear relationship, independent of root restriction, was observed between the relative rates of root elongation and leaf expansion. Similar relationships with the relative rates of increase in root number and dry biomass were due to their covariance with root elongation. These data are consistent with the hypothesis that root elongation is functionally linked to leaf expansion via the synthesis of hormones in actively growing root apices. The influence of partial root restriction on leaf expansion was also examined. One or both halves of a split root system was enclosed in a 30 cm3 polyethylene cell. Leaf expansion was reduced in plants with only a portion of their total root system physically restricted. Compensatory growth in the unrestricted portion of the root systems resulted in total root growth at final harvest being similar to plants with all their root system unrestricted. Analysis of the relative rate of leaf expansion (RA) of individual leaves along the stem axis revealed two distinct phases in response to root restriction. In the first phase, apparent about 28 days after treatments were initiated (DAI) and observed in leaves that started expansion 3, 7, and 14 DAI, RA was reduced in plants with one or both root sub-systems in a restriction cell. The second phase, detected 42 DAI and observed in leaves that started expanding 21 and 28 DAI, was characterised by a higher RA in plants with a portion of their root system restricted compared to unrestricted plants. Proportionately more assimilate was partitioned to stems of plants with two restricted root sub-systems compared to plants with either a single or non-restricted root sub-system. No differences in leaf water potential or photosynthesis of leaves were observed among treatments. Conclusions drawn from these data support the involvement of chemical signals in maintaining coordination between root and shoot growth in container-grown plants. These conclusions are discussed with reference to the literature, and a model is proposed to explain root-shoot coordination in terms of root-sourced cytokinin and shoot-sourced auxin. Avenues for future research to test hypotheses arising from this model are identified and discussed, as are possible horticultural ramifications. Emphasis was placed in the study on improving analytical methodology of growth analysis of whole-plant studies. Experimental precision was increased in these experiments by using cluster analysis to allocate plants to blocks based on leaf area, with a developmental study showing that the mean coefficient of variation of groups formed from cluster analysis was between two and fives times smaller than that of groups formed from visual assessment. A statistical model for non-destructively estimating the leaf area of tomatoes was developed based on the length of the mib-rib of each compound leaf and its position on the stem. Although the model was accurate to within about 2.5% of actual leaf area, it was not stable in time. It was concluded that when non-destructive estimation of tomato leaf area is required, the prediction model must be developed while the main experiment is being conducted. A hybrid method of growth analysis, incorporating both functional and univariate statistical approaches, provided more flexibility and information than standard functional or classical analytical methods. The hybrid method yielded replicated estimates of growth analysis indices, providing opportunity for further evaluation of the derived data using multivariate analytical techniques including path, canonical correlation, and canonical discriminant analysis. keywords: allometric relationships, assimilate partitioning, biometrics. Chanter function, cluster analysis, containerised plants, hydroponics, leaf expansion, local error control, plant growth analysis, relative growth rate, Richards function.
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    Studies of the factors affecting the yield and quality of single truss tomatoes : a thesis presented in partial fulfilment of the requirements for the degree of Doctorate of Philosophy in Horticultural Science at Massey University
    (Massey University, 1996) Morgan, Lynette Stella
    This research was conducted to evaluate the potential of the single truss system of tomato production to produce high yields of quality fruit under New Zealand conditions. The NFT hydroponic system was used to grow the plants so that nutrient solution conductivity could be maintained close to predetermined levels. In the first experiment three cultivars were compared. At the time of fruit set of the first truss four conductivity treatments (2, 4, 6 and 8 mS cm-1) were applied. Yield and fruit quality data was obtained from each of six crops over an 18 month period. Yield (fruit size) decreased with increasing conductivity for all three cultivars. Season also had a significant effect on yield, with an April harvested crop having the highest yield. Both fruit brix and titratable acidity were increased at the higher conductivity levels. There were also cultivar and seasonal differences in fruit quality, with the cherry cultivar 'Cherita' consistently producing the highest brix and titratable acidity levels. Brix levels were found to be low in the December harvested crop, while acidity was highest in the December, April and July harvested crops. Season, solution conductivity and cultivar influenced plant leaf area and leaf area index. Solution conductivity also effected foliar mineral levels, as did cultivar. Three successive multi truss crops were grown in a pumice media system to provide fruit quality data for sensory evaluation and comparison with single truss and commercial compositional fruit quality. The same three cultivars as were compared in the single truss crop experiment were grown at three conductivity levels (2, 4 and 6 mS cm-1) applied at the time of fruit set of the first truss. Fruit samples were taken from the 5th and 6th trusses for quality evaluation. Season and solution conductivity had an effect on fruit dry matter percentage and brix. Fruit shelf life was affected by season, conductivity and cultivar, with a longer shelf life obtained from fruit grown at the higher conductivity levels. The December harvested crop had the lowest overall shelf life. Fruit firmness was only affected by solution conductivity, with the fruit from the higher conductivity treatments being firmest. Sensory evaluation of Rondello fruit on three separate occasions showed that the higher conductivity treatment scored highest for most attributes, and that these sensory scores correlated well with brix and titratable acidity levels. A second single truss crop experiment focused on manipulation of the source/sink relationship (fruit and leaf number combinations) of three successional crops and the effect of spring and winter CO2 enrichment on two of the three crops. The summer crop also evaluated the effect of crop shading and source/sink relationship on fruit yield, as high fruit temperatures were suspected to have reduced yield in the previous summer single truss crops. Yield and fruit quality data was collected from all three crops, along with fruit and environmental temperature recordings from the summer crop. It was found that season and fruit number effected yield, with the 8 fruit per plant treatment resulting in the greatest yield. Leaf number (either 2 or 3) and season affected fruit dry matter percentage, brix and leaf area, while fruit number influenced brix levels. CO2 enrichment (1000 ppm) had no effect on either spring or winter fruit yield, but did advance crop maturity allowing an extra crop per year to be produced. Thus yearly yield was increased by CO2 enrichment. CO2 enrichment improved fruit quality in the spring crop, but had no effect on the winter crop. Shading of the summer crop resulted in an increase of 10% in total fruit yield and 19% in marketable fruit yield, due to the presence of smaller fruit and heat induced ripening disorders in the unshaded crop. Both leaf number and shading treatments affected titratable acidity, with unshaded fruit having greater percent citric acid levels. Shelf life and fruit firmness was greater in the shaded crop. Air, canopy and fruit temperatures were reduced under shade, with exposed fruit often reaching extreme temperatures (above 40°C). Having established that leaf and fruit temperatures were reaching extreme levels during the summer in a single truss cropping situation, the effect of these temperatures on photosynthesis and fruit respiration was examined. The effect of leaf age on photosynthesis was also examined as single truss plants do not continue to produce young foliage to maintain photosynthesis levels. After harvest, net photosynthesis and the light compensation point, which had been increasing began to fall rapidly at all light levels. It was found that after an initial drop as leaves matured, leaf age did not effect net photosynthesis. Plants exposed to 800 PAR showed maximum net photosynthesis at temperatures between 25 – 27°C. Net photosynthesis ceased at 43°C. Fruit truss respiration rates were determined at 4 temperatures (25, 30, 35 and 40°C), on 3 occasions (18, 26, 36 and 40 days after fruit set). 5 different tissue sample combinations were assessed comprising, the whole truss with sealed and unsealed cut surfaces, fruit only with sealed and unsealed calyx scar and calyx, peduncles and plant stem only. It was found that temperature, truss portion assessed and stage of fruit maturity all affect fruit respiration rate, with the fruit only (calyx scar unsealed) resulting in the greatest CO2 efflux. It was concluded that while the fruit epidermis is relatively impermeable to gas escape, the main route for Co2 is through the calyx scar. Mature green fruit had the greatest response of increased CO2 production with increasing temperature, while temperatures above 25°C disrupted the climacteric pattern of CO2 evolution. It was concluded that in single truss plants, when temperatures were above 30°C, net photosynthesis is reduced, while fruit respiration begins to increase rapidly, both responses having a detrimental effect on yield. The single truss system was shown to produce yields and fruit quality equal to those of good multi truss commercial tomato producers in New Zealand. This was achieved by CO2 enrichment for crop advancement and summer crop shading, while moderate levels of solution conductivity produced good quality fruit. However, there is the possibility of further improving these yields by utilisation of other technologies such as a movable bench system and manipulation of plant density, timing of conductivity application, and different cultivars. The potential of this system for high quality, high yielding tomato fruit production warrants commercial evaluation.