The impact of changing light levels and fruit load on the pattern of tomato yields

Summary

Experiments in glasshouse and controlled environment facilities investigated the effect of different fruit removal and lighting/shading treatments on the pattern of tomato yields. While the removal of flowering trusses resulted in a yield loss about eight weeks later, there was little loss in cumulative yield as assimilates were distributed to neighbouring trusses. In the growth room experiment, increased photosynthetic photon flux density (PPFD) for one week resulted in a period of increased yield from 4–6 weeks after the start of the treatment, followed by suppressed yields due to smaller fruits on subsequent trusses. However, neither fruit load nor assimilate availability appeared to be responsible for the fluctuations in yield recorded within the glasshouse crop. In this experiment fruit size remained fairly consistent (except when fruit removal treatments were applied), whereas the number of fruits picked per week exhibited much greater variability. This was the case even when all trusses were pruned to leave five fruits, and so was not due to a cycle in the number of fruits set per truss. The flushes in yield were found to be a consequence of a hastening of fruit maturation.     

Competition effects between fruit trusses of the tomato plant

There were 6 treatments in each of 2 series covering the range from 1–6 fruit trusses per plant. The terminal growing-points were removed 2 leaves above the last inflorescence of each treatment in the “limited-stem” series, and 2 leaves above inflorescence 6 with inflorescences removed as necessary in the “full-stem” series.The yield of trusses 2–5 in the “full-stem” and of truss 2 in the “limited-stem” series was reduced by the presence of subsequent trusses. Similar trends were apparent with trusses 3–5 of the “limited-stem” series. It was suggested that the reduction in yield was due to competition between trusses for assimilates resulting in smaller and/or fewer fruit per truss.Data is presented to suggest that the net assimilation rate in the tomato plant can be reduced due to lack of fruit load and that fruit yield can be limited simultaneously by lack of both source and sink strength.     

不同茬口日光温室番茄干物质生产与分配

 以番茄的果穗和果穗下的三片叶及其相应的茎作为一个源库生长单位，对不同茬口日光温室番茄的干物质生产与分配规律进行了研究。结果表明：植株在前7穗果同时存在的情况下，从下到上不同源库生长单位内果实所分配到的干物质比例在42.6%～98.6%之间，即随着果穗数从下而上的不断增加，每产生一穗果实，各源库生长单位果实的干物质分配率下降约6%。不同茬口日光温室番茄受外界环境影响显著，干物质生产表现出明显的季节性差异，果实干物质分配率在越冬茬、早春茬和春夏茬分别为72%、62%和59%，春夏茬果实干物质分配率最低，这与其生长后期遭遇高温，坐果率降低有关；越冬茬生长前期100 d的干物质积累量只有后100 d的1/3，与其生长期内低温弱光有关。     

Effect of Time of Application of Fertilizer Nitrogen on the Growth,Flower Development and Fruit Set of Maiden Apple Trees,Var. Lord Lambourne,and on the Distribution of Total Nitrogen Within the Trees

Fertilizer nitrogen was applied to pot-grown trees during the year of initial scion growth either as “spring N”, “summer N” or “autumn N”, while other trees were left untreated—“minus N”. Tree performance was followed until fruit set the following summer.

At regular intervals whole trees were sampled, divided into as many as seven different parts, which were separately weighed, dried and analysed for total nitrogen. Specimens were also taken for histological examination of flower bud development.

The large amount of fertilizer given as “spring N” resulted in extensive root damage from which the trees did not recover fully; nevertheless they produced large, vigorous scions. After “spring N” and “summer N” at lower dosages the total N content of all parts increased substantially and rapidly. “Autumn N” was absorbed more slowly and remained largely in the roots during the winter, when a considerable amount of root growth took place.

Flowers were initiated in late July or early August on all trees except those given “spring N”, on which flower primordia were not initiated until September. The development of flower buds was accelerated during September on “summer N” trees compared with those left untreated. From the end of November until the end of March no further differentiation took place on “minus N” or “spring N” trees, but it continued on the other treatments, especially following “autumn N”.

“Summer N” and “autumn N” trees were 4–5 days in advance of the others in flowering. “Summer N” trees had large flowers and large green primary leaves, whereas those on “autumn N” trees were smaller and the leaves were initially pale, though turning dark green during blossoming.

When the blossoms were self-pollinated under controlled conditions virtually no fruit was set on “minus N” and “spring N” trees, but “summer N” gave an appreciable set and “autumn N” a heavy set. Only the “summer N” and ”autumn N” flowers had ovules that remained viable six days after anthesis, which was the minimum period found necessary for the pollen tubes to effect fertilization.

It is suggested that fertilizer nitrogen stimulates the synthesis of a kinin-like factor in the roots and that the difference in response to applications at different times of year depends upon the stage of development of the flower buds when this factor reaches them.     

Flower morphology and number of aubergine (Solanum melongena L.) in relation to fruit load and auxin application

The effect of fruit load and auxin application on the flower morphology and flower number of two aubergine cultivars was investigated under greenhouse conditions. The flowers of plants that did not set fruit showed only minor fluctuations in flower and pistil mass, and in style and anther length. However, when plants were allowed to set fruit by pollination, flower and pistil mass, and style (but not anther) length were significantly reduced during the stage of fruit growth. Style length was also reduced in flowers formed after fruit had been set parthenocarpically by the application of auxin (IAA), but there was no significant effect of IAA on style length in the absence of fruit development. The number of flowers was reduced in the presence of IAA (with or without fruit set), or following fruit set by pollination. It is suggested that fruit load and development affect flower mass and style length of aubergine whereas auxin influences the number of flowers.     

Effects of inflorescence removal on the fruit set of the remaining inflorescences and development of the laterals on one year old apple (Malus domestica Borkh.) branches

Summary

Inflorescences are known to be important physiological sinks especially when they set fruit. The effect, over two successive years, of inflorescence removal on one year old wood was investigated on apple (Malus domestica Borkh.). The study was carried out on medium vigour (around 30 cm) branches of cv. Granny Smith. On one set of branches (control) the inflorescences were untreated, while on two other sets, one-third and two-thirds of inflorescences (spur leaves, bourse-shoot and flower cluster) were removed at full bloom. The first analysis investigated the fruit setting ability of remaining inflorescences. The results generally confirmed previous results on the positive correlation between the number of leaves and flowers of the inflorescence and fruit set, and also the higher fruit set on two year old wood as compared with one year old wood. On one year old wood, inflorescence removal treatments tended to increase the fruit set of inflorescences with a low number of leaves and flowers leading to a level of fruit set similar to that of inflorescences with a larger number of leaves and flowers. On two year old wood, in the following year, only the two-thirds treatment increased fruit set consistently compared with the control. A second analysis investigated the effect of inflorescence removal on lateral shoot development. It was shown that the treatments had a little effect on quantitative growth (length, diameter) of the laterals per se. On the other hand, the removal of two-thirds of the inflorescence significantly stimulated the development of fruitful inflorescences the following year. Results are discussed in relation to the local versus global physiological integration at the branch level.     

Effects of Nitrogen Supply During Propagation on Flowering and Fruiting of Glasshouse Tomatoes

During the propagation of tomato plants, which were later stopped at the fifth truss, two levels of nitrogen were applied in factorial combination before and after initiation of the first truss. The high level of nitrogen prior to initiation produced earlier flowering and an increased weight of fruit in the first truss. 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 constancy of the final crop was explained in terms of the concept of a fixed fruit load.

Under the conditions of light in this experiment the results did not suggest that vigorous early growth was detrimental.     

Seasonal Changes in the Diameter of Secondarily Thickened Roots of Fruit Trees in Relation to Growth of Other Parts of the Tree

The diameters of apple and cherry tree roots, between 1·5 ft. and 6·0 ft. from the base of the tree trunk, were measured with a microscope through glass observation panels at intervals during 4 years. The rate of root thickening was low in June and was most rapid from mid-July to mid-September, whereas rapid trunk thickening occurred in June and continued until September. The period of maximum root thickening coincided with a second peak in the production of new white extension roots when the intensity of shoot growth was decreasing.

Some root thickening was detected one week after bud burst but many roots showed no thickening until July or August. At this distance from the trunk there was no progression of thickening along the root from the proximal to the distal end.     

Effects of CCC on the occurrence of tomato puffy fruits and the endogenous cytokinin activities

CCC treatment at flowering time suppressed the occurrence of tomato fruit puffiness in solution culture. Root application, truss spraying and whole plant spraying of CCC were all effective in correcting fruit puffiness, and truss spraying did not decrease fruit weight, unlike the other two treatments. For practical use, truss spraying might be the best method to control tomato fruit puffiness.Cytokinin contents in the xylem sap of tomatoes increased when CCC was applied to roots. This suggests that cytokinin biosynthesis in roots was increased by CCC treatment. Cytokinin activities in tomato fruits at an early developmental stage were also markedly increased by CCC treatment to roots. These results suggest that the CCC effect on the control of tomato fruit puffiness might be partly due to increased cytokinin activity in the developing fruit.     

缩节胺对越冬番茄的生长调控效应研究

以‘雪莉’番茄为试材,研究定植后不同施用时间、不同浓度缩节胺对日光温室硬果型番茄生长和产量的影响。结果表明:越冬番茄定植前2d用100mg/L缩节胺(DPC)灌根1次,并于定植后第4天用100mg/L缩节胺喷施1次处理的第1花穗下茎高和第1花穗下节间长最小,抑制徒长的效果最佳,且坐果率、单果重、小区产量最高。而定植后第4天用50mg/L缩节胺喷施1次处理的抑制徒长效果较差,坐果率、单果重、小区产量最低,与CK相近。综合来看,缩节胺灌根处理的抑制徒长效果和增产效果明显优于喷施处理方式,定植前灌根处理的抑制徒长效果和增产效果明显优于定植后灌根处理方式;2次处理的抑制徒长效果和增产效果明显优于1次缩节胺处理。处理Ⅸ(定植前2d用100mg/L缩节胺灌根1次,并于定植后第4天用100mg/L缩节胺喷施1次)的抑制徒长效果最好,与处理Ⅱ(定植后第4天用100mg/L缩节胺喷施)相比,处理Ⅵ对第1花穗下茎高的抑制效果比处理Ⅱ提高了48.3%,产量也增加23.5%。     

The effect of different day/night temperature regimes on growth,development and yield of glasshouse tomatoes

Summary

The response of glasshouse grown tomatoes, cv. Counter, to day/night temperature regimes was examined in two consecutive years. In both years three day/night temperature regimes, with the same average 24-hour temperature, were applied in duplicate, i.e. high/low, equal, and low/high. Differences in temperature were maintained from three days after planting (4 December 1984 and 3 February 1986) until 13 May 1985 and 1 May 1986, respectively. Plant development (increase in number of trusses) was not affected.by the temperature regime. Growth in length of the stem was strongly reduced by a lower day temperature. In the first experiment the crop at the low day temperature treatment was damaged by leaf scorch, most likely caused by low transpiration. Consequently, early yield was lower for this treatment. In the second experiment no leaf scorch occurred and no significant differences in early yield were found. Final yield and average fruit weight, until 1 July for both experiments, were higher at the higher night temperature. Shelf life of the fruits and internal quality was not influenced by the temperature regime. Thus, the length of a tomato plant can be manipulated by the difference between day and night temperature, while development and early yield depend greatly on the average 24-hour temperature. Final yield can be higher at higher night temperature and the same average temperature because the crop is more robust. Temperature control based on average 24-hour temperat-ure can be used to minimize energy. consumption and, together with other growth factors, to optimize financial yield.     

Effects of auxin application on fruit formation in tomato growing under stress temperatures in the field

Summary

Tomato (Lycopersicon esculentum L. Mill) cultivars Early Urbana and Red Clode were grown in the field at adverse temperatures (stress regimes) until they set fruit in two growing seasons (Autumn and Spring) during 1999 and 2000 in Ahwaz (Southern Iran). To test the effectiveness of auxins in enhancing fruit set, racemes of tomato were sprayed during early fruit set with 25, 50 and 100 mg l^–1 4-chlorophenoxy acetic acid (4-CPA) and indole-3-butyric acid (IBA) followed by two additional applications at three intervals. The control plants were treated with deionized water. At harvest, racemes from autumn and spring plantings that were treated with 4-CPA had more large fruits than the control racemes. In both growing seasons, neither cultivar showed a significant difference in fruit set in plants treated with IBA, compared with controls. The ratio of fruit/flower in all racemes treated with 4-CPA increased significantly compared with the other treatments. However, auxin treatments did not significantly affect the number of flowers per raceme. Plants treated with 4-CPA produced the highest yield of marketable fruit. The greatest increase in total yield and parthenocarpic fruit occurred with 4-CPA treatments. Also, there was little difference between concentrations of 4-CPA on fruit set in both cultivars. It may be concluded that the response of fruit setting in tomato to either low or high temperatures regimes was auxin dependent and that 4-CPA was more effective than IBA.     

Dry-matter partitioning in a tomato crop: Comparison of two simulation models

SUMMARY

TOMSIM(l.O) and TOMGRO(I.O) are two dynamic models for tomato growth and development. Their sub-models for dry-matter distribution between leaves, stem and fruits were compared and discussed. In both models the simulated dry-matter distribution is regulated by the relative sink strengths of the plant organs. These sink strengths are quantified by the potential growth rates of individual organs, i.e. the growth rates under conditions of non-limiting assimilate supply. This approach is general and not limited to the tomato crop. In TOMGRO(J.O), fruits, leaves and internodes stay within age classes and move from class to class during development, whereas in TOMSIM (1.0), record is kept of every fruit truss separately but leaves and internodes are lumped together (i.e. no record of weight or leaf area per age class as in TOMGRO(l.O)). In TOMSIM(1.0), vegetative sink strength is a constant, whereas in TOMGRO(l.0) it is calculated from potential area expansion rate of leaves and specific leaf area. In both models, the ratio between leaf growth and stem growth is constant. In TOMGRO(l.O) there is a feed-back mechanism which controls the vegetative/generative balance: a higher demand/supply ratio for assimilates induces higher fruit abortion rates. In TOMSIM(l.O) the number of fruits set per truss is not simulated, but is an input to the model. TOM SIM (1.0) functions representing flowering rate, fruit growth period, vegetative sink strength and fruit sink strength were compared with similar TOMGRO(l.O) functions, in their dependence on temperature and physiological plant age. A sensitivity analysis was made for the effects of temperature, flowering rate, and fruit and vegetative sink strengths on dry-matter distribution for both models. A validation of both models was based upon periodic destructive harvests in: 1) a greenhouse experiment in Wageningen, using a round tomato cultivar, consisting of a control treatment and a treatment where every second truss was removed at anthesis, and 2) two greenhouse experiments conducted in Montfavet, using a beefsteak tomato cultivar. Daily shoot dry-weight increase, average 24 h greenhouse temperatures and numbers of fruits set per truss (in TOMGRO(l.O) numbers of flowers per truss) were inputs to the models. In general dry-matter distribution was simulated well by both models for the cultivar and conditions where they were developed. TOMGRO(1.0)'s poor performance in one of the validations resulted from the absence of an assimilate storage pool. To achieve reasonable agreement between measurements and simulations for situations other than where the models were developed, parameter adjustments had to be made, most likely reflecting cultivar differences. Strong and weak points of both models are discussed.     

Growth rates of glasshouse tomato fruit in relation to final size

The individual growth rates of the first five tomato fruits on 25 trusses of similar age within a crop grown in commercial glasshouse conditions were assessed from anthesis to ripening during April and May. Final size of fruit at ripening was proportional to the maximum rate of increase in fresh weight, about 40 d after anthesis, and related to the maximum rate of increase in diameter, between 15 and 20 d after anthesis, even though ripe fruit fresh weight varied from 20 g to over 100 g. On any one truss these fruit ripened within the same week, regardless of fruit size and prevailing growth rate. These findings suggest that final size was related to the peak fruit growth rate rather than the duration of development. A high growth rate late in development did not delay fruit ripening. The implications for recent continuous measurements of the diameter growth rate in young fruit are discussed.     

Growth characteristic and sink strength of fruit at different CO2 concentrations in a Japanese and a Dutch tomato cultivar

The aim of the present study was to elucidate how fruit growth was limited by the source and sink capacities in a Japanese (‘Momotaro York’) and a Dutch (‘Dundee’) tomato cultivar. The two cultivars were grown hydroponically with a high-wire system in greenhouses for 25 weeks, and the growth characteristics and sink strength of fruit were determined. Fruits were pruned to four (4F) or one (1F) per truss. The latter were used to determine potential fruit growth, an indicator of fruit sink strength. Growth was also determined under normal (LC) and enriched (HC, 700 μmol mol⁻¹) CO₂ concentrations to examine the effect of source enhancement on fruit production. In both cultivars under normal CO₂, the growth rate of fruit pruned to 4F per truss was lower than that in 1F, indicating that maximum potential fruit growth was not achieved. Under HC conditions, fruit growth rate of ‘Dundee’ achieved in 4F trusses was lower than that in 1F. In ‘Momotaro York’ in HC, fruit growth in 4F trusses was close to potential. This implies that fruit growth was source-limited irrespective of CO₂ concentrations in ‘Dundee’ cultivar while fruit growth in ‘Momotaro York’ under normal and enriched CO₂ conditions was limited by source and sink strengths, respectively. Adjustments of cultural practices including increasing fruit number per truss and/or genetic approaches to enhancing fruit sink strength by breeding may improve fruit yields of Japanese cultivars under high source/sink conditions.     

Effects of drought on fruit set,yield and quality of custard apple (Annona spp. hybrid) ‘African Pride’ plants

Summary

Studies were conducted to evaluate the effects of drought during flowering for both container- and field-grown trees, and during fruit development for container-grown trees, on subsequent growth, flowering, yield and quality of the custard apple ‘African Pride’ in subtropical Australia. Moderate drought (ψ_L=–1.5 MPa) reduced shoot growth by 20–30% and increased the number of flowers per lateral by about 40% compared with well-watered controls due to reduced apical dominance and increased lateral branching. Overall fruit set was not adversely affected by drought. Drought also increased the number of fruit harvested per tree by 47% compared with well-watered controls. This response was mainly due to the increase in flower number per tree. Drought reduced average fruit size by 11% possibly due to effects on cell division in the first 4–6 weeks after fruit set or on net carbon assimilation. In summary, mild to moderate drought during the flowering period and fruit set increased flowering without adversely affecting fruit set, but decreased fruit size.     

Winter glasshouse strawberry production: A sequential cropping programme

A schedule was devised to produce glasshouse strawberries from December to March, which is a period when few English strawberries are on the market. In an experimental test, fruit of good quality was obtained at the times planned. Gross yields from ‘Red Gauntlet’ were approximately 50 % greater than those from ‘Glasa’ and the respective marketable yields were 67 % and 60 % of gross yields. Total crop weight increased linearly with the lateness of the season, while average fruit size decreased, also linearly. Yields per plant were variable, the greatest being more than double the average, and were correlated with the number of flowers and number of trusses.     

The Effect of Truss Removal on the Yield of Early Sown Tomatoes

The effect of removing individual trusses from glasshouse-grown tomatoes was investigated and the results are discussed in terms of carbohydrate source/sink relationships. Removing a truss resulted in yield increases on some of the remaining trusses both above and below the one removed, the largest increases occurring on the trusses adjacent to the removed truss with smaller increases on the more distant ones. This general pattern of yield increases occurred whichever of the first nine trusses was removed. The total yield from plants reduced to nine trusses varied from 91% to 99% of the yield from the control plants with ten trusses, depending on the position of the truss removed. The results suggest that most of the translocated material receive by a truss is derived from the leaves in its immediate vicinity. Also that the removal of a truss sink results in apical and basal movement of the available assimilate to the remaining trusses, perhaps via the internal and external phloem.     

整枝对西瓜生长和结果的影响

整枝有调节西瓜植株生长势、提高叶片素质、促进坐果、增大果形等效应，但在一定程度上有减少雌花数目和结果数，降低产量等副作用；整枝应与适当密植结合起来以弥补其负面效应。在生产中，①早熟栽培可增加种植密度、减少蔓数，以增加果数，提高早期产量；②露地栽培则可减少种植株数，增加蔓数，以提高叶面积，增大果形，增加产量。③主蔓的去留与品种有关，生长势弱的品种主蔓应予保留，长势强的品种则宜摘除主蔓，利用侧蔓结果     

渭北黄土高原苹果不同砧穗组合幼树根系发育和分布的特征

砧穗组合选配是苹果矮砧集约栽培模式的关键环节之一,幼树的早果性和易成形性是评判砧穗组合优劣的重要指标,这与幼树根系分布密切相关。以中国苹果生产上8种常见砧穗组合的3年生幼树为试材,采用壕沟法对幼树根系分布特征进行了调查分析。结果表明:8种砧穗组合幼树根构型可以分为M系自根砧、SH系自根砧、乔化实生砧木、M系中间砧和SH系中间砧等5大类。3年生幼树根系在水平和垂直方向分布的主要区域,均为0~60 cm范围,且随着距树干距离的增大而减少。不同砧穗组合,根系长度以直径2 mm级别的根系最长,其次是直径2~5 mm的,10 mm以上的最短。乔化实生砧木较无性系矮化砧木粗根多,而须根少;矮化砧木中,M系砧木根系构成以须根为主,而SH系和青砧系砧木须根均较少。砧穗组合幼树的地上分枝数、短枝比例和花芽数等早果性指标与细根(直径2 mm)根系数量、根长密度和根表面积密度呈显著正相关关系。通过对各砧穗组合易成花和易成形的综合评价,认为在渭北黄土高原有灌溉条件的地区,M系自根砧和中间砧组合早果性好和易成形较好,而SH系组合较易成形,但早果性较差,乔化组合早果性最差,这与它们的根系分布特征密切相关。