Quality Of Greenhouse Tomato Research Articles

Integrating Smart Greenhouse Cover, Reduced Nitrogen Dose and Biostimulant Application as a Strategy for Sustainable Cultivation of Cherry Tomato

Fruit yield and quality of greenhouse tomatoes are strongly influenced by light conditions and nitrogen (N) availability, however, the interaction between these factors is still unclear. We evaluated the effects on cherry tomatoes of two tunnel plastic covers with different optical properties and three N doses, also in combination with a biostimulant treatment. We compared a diffuse light film (Film1) and a conventional clear film (Film2), and three N levels, corresponding to 50% (N50), 75% (N75) and 100% (N100) of the optimal dose, with and without a microbial plus a protein hydrolysed biostimulant, compared to a non-treated control. The three experimental treatments significantly interacted on several yield and quality parameters. In control plants (untreated with biostimulants), the early yield was higher at reduced N doses compared to N100, with greater increments under the diffusive Film1 compared to the clear Film2 (+57.7% and +37.0% vs. +31.7% and +16.0%, in N50 and N75 respectively). Film1 boosted the total fruit production at all the N rates and with or without biostimulants, compared to Film2, with stronger effects under sub-optimal N (+29.4% in N50, +21.2% in N75, and +7.8% in N100, in plants untreated with biostimulant). Total yield decreased with decreasing N levels, while it always increased with the application of biostimulants, which counterbalanced the detrimental effects of N shortage. Quality traits were mainly affected by the cover film and the biostimulant treatment. The diffusive film increased the content of carotenoids, lycopene and total phenols compared to the clear one, and the biostimulants increased texture, soluble solids, phenols and ascorbic acid compared to the untreated control. It is worth noting that in plants fertilized at 75% of the reference N dose, the biostimulants determined higher yield than the N100 untreated control, under both the covers (+48% in Film1 and +20% in Film2). In conclusion, the diffusive film improved the fruit yield and quality of greenhouse tomatoes in the spring–summer period, presumably avoiding plant stress due to high-intensity direct light. Reduced N rates limited the plant productivity, however, the biostimulant application was effective in compensating for the detrimental effects of sub-optimal supply of N synthetic fertilizers.

Silicon application mitigated the adverse effects of salt stress and deficit irrigation on drip-irrigated greenhouse tomato

Tomato (Solanum lycopersicum L.) is an important vegetable crop around the world, and water scarcity and soil salinization are two major unfavorable factors limiting the fruit yield and quality of greenhouse tomato in arid and semi-arid regions. The application of exogenous silicon has been reported to enhance tomato yield under salt or drought stress, but its effect under combined salt-drought stress remains unclear. A two-season (autumn 2021 and spring 2022) experiment was conducted with three irrigation levels (I1, 90%−100% θf, where θf is the field capacity; I2, 70%−80% θf; I3, 50%−60% θf), two soil salinity levels (S0, 0.1%, g/g; S1, 0.4%, g/g) and two silicon application rates (T0, 0 mM; T1, 2.4 mM) to explore their combined effects on leaf silicon content, photosynthetic parameters, fruit yield, nutrient yield, crop water productivity (WP), nitrogen uptake and utilization, nutrient water productivity (NWP) and economic benefit of drip-irrigated greenhouse tomato. The results showed that deficit irrigation and salt stress exerted significant inhibiting effects on leaf silicon content, photosynthetic parameters, tomato yield, and water-nitrogen productivity, but the inhibition was alleviated by silicon application, which increased leaf silicon content by 67.0%, net photosynthetic rate (Pn) by 25.3%, fruit yield by 12.3%, WP by 11.9%, nutrient yield by 10.0% (titratable acids) - 27.4% (soluble sugars) and NWP by 9.2% (titratable acids) - 26.1% (soluble sugars) on average. The average fruit yield over the two growing seasons was 66.01, 54.29 and 44.31 t ha−1 under I1, I2 and I3, and the silicon application increased average leaf silicon content by 71.9%, 65.2% and 63.0%, Pn by 11.1%, 12.9% and 7.6%, and fruit yield by 12.8%, 16.2%, and 8.1% at the three irrigation levels, respectively. Plant nitrogen uptake (NU) and nitrogen partial factor productivity (NPFP) increased but nitrogen use efficiency (NUE) tended to decrease with the increasing irrigation level, while silicon application improved NUE by 3.9% and 2.2% and NPFP by 13.8% and 11.7% in the two growing seasons, respectively. Silicon application significantly increased net profit by 24.3% and 17.7% in autumn 2021 and spring 2022, respectively. According to the principal component analysis, I1T1S0 ranked first in both growing seasons. The correlation matrix showed that fruit yield was positively correlated with leaf silicon content, Pn, stomatal conductance, WP, NU, NUE, NPFP, nutrient yield and net profit, while it had negative correlation with NWP. In conclusion, exogenous silicon application can improve the fruit yield and nutrient yield of drip-irrigated greenhouse tomato by enhancing leaf silicon content and photosynthetic capability under drought-stressed and salt-affected conditions.

Effects of Water and Nitrogen Coupling on Growth, Yield and Quality of Greenhouse Tomato

Irrigation water is essential for greenhouse plants because it is the only water source in the greenhouse. In addition, escalating water costs and expensive fertilizers have raised concerns about adopting advanced technology to improve water and nitrogen utilization efficiency. This study aimed to explore the effects of different water and nitrogen application rates on yield, fruit quality, and water and nitrogen utilization efficiency in southeast China. Plants were irrigated every 7–10 days at different proportions of crop evapotranspiration (ETc) based on the modified Penman–Monteith formula (ET0). The crop coefficient (Kc) was adopted as 0.6, 1.15, 1.15 and 0.9 during the seedling stage, flower stage, the mid-season stage and the end of the season stage, respectively. There were three water levels—0.75 ETc (W1), 1.0 ETc (W2), 1.25 ETc (W3)—and four nitrogen levels—120 (N1), 220 (N2), 320 (N3), and 420 kg N hm−2 (N4)—and a total of 12 treatments, with the application completely randomized by using block design in the experiment. Tomato yield was improved by nitrogen supply. However, nitrogen application had a negative effect on tomato yield when the nitrogen level was applied above 320 N ha−1. The maximum water use efficiency (WUE) value of 30.5 kg m−3 was observed at W2N3, and the maximum nitrogen use efficiency (NUE) value of 684.4 kg kg−1 N was observed at W1 treatment with N1. The net photosynthetic rate of tomato leaves could be increased by reasonably increasing water and nitrogen application. The dry biomass increased with the amount of water and nitrogen in the range of (0.75–1.0) ETc and (120–320) kg ha−1. The best values of tomato quality parameters (Vc, Lycopene, soluble protein et al.) were observed at W2N3. The irrigation level of 1.0 ETc and nitrogen level of 320 N ha−1 was recommended as the best combination of water and nitrogen for greenhouse tomato cultivation in the experimental areas.

Leaf area and its impact in yield and quality of greenhouse tomato (Solanum lycopersicum L.)

This study aimed to estimate the tomato leaf area index (LAI) by comparing two methods (destructive and interception of photosynthetically active radiation) and the consequent relationship to fruit yield and quality. The experiment was carried out in a greenhouse with tezontle (red volcanic scoria) as the substrate and a drip irrigation system. The experiment consisted of three treatments: T1, T2 and T3, with one, two and three stems per plant, respectively. The LAI was measured with a ceptometer that estimates the intercepted radiation above and below the canopy. Maximum LAI was found at 1413 cumulative growing degree days (CGDD). Those indexes were 3.69, 5.27 and 6.16 for T1, T2 and T3, respectively. Individual correlation models were fitted linearly between the two methods. The R2 values were 0.98, 0.99 and 0.99 with yields of 20, 18 and 17 kg m-2 for T1, T2 and T3, respectively. In addition, T1 produced better fruit size quality with approximately 69, 23 and 8% classified as first, second and third class, respectively. Only 1% was classified as a small fruit. Increasing the number of stems per plant increased the LAI and fruit number but decreased fruit size. Highlights: The leaf area index (LAI) is a very important variable for growth and development of crops. The ceptometer proved to be a fast, useful and statistically reliable method to estimate LAI. The increase of photosynthetically active radiation favors the photosynthetic efficiency per unit area. The number of stems per plant increase the LAI, dry matter accumulation, plant height and the number of fruits. However, the size of fruit decreases.

Application of a Biostimulant (Pepton) Based in Enzymatic Hydrolyzed Animal Protein Combined With Low Nitrogen Priming Boosts Fruit Production Without Negatively Affecting Quality in Greenhouse-Grown Tomatoes.

Improved nutrient use efficiency together with the use of biostimulants have been little explored thus far to improve fruit yield and quality in economically relevant crops. The aim of this study was to determine the additive or synergistic effects, if any, of the application of an enzyme hydrolyzed animal protein biostimulant (Pepton) combined with priming with low nitrogen (N) in the production and quality of greenhouse tomatoes. Biostimulant treatment (Pepton at a dose equivalent of 4 kg/ha) was applied by ferti-irrigation for 2 months during the vegetative phase both in controls (watered with nutrient solution) and nutrient efficient crop (NEC), in which plants were primed with low N by exposing them to a 30% N deficiency for 2 months, and then recovered for 1 month before fruit production. Foliar water and N contents, pigments, maximum PSII efficiency (Fv/Fm ratio), and phytohormones [including abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), and cytokinins] were measured prior and at 4 and 8 weeks after the first application. Fruit production and quality [as indicated by total soluble sugars (TSS) and acidity (TA), and the contents of lycopene, vitamin E, and vitamin C] were measured 1 month later at harvest. Priming with low N availability (NEC plants) doubled (p < 0.001) fruit production (due to an increase in the number of fruits), tended to increase (p = 0.057) by 20% the amount of TSS and increased (p < 0.05) the contents of lycopene (by 90%) and vitamin E (by 40%). Pepton displayed a tendency, almost significant, to improve (p = 0.054) total fruit production both in control and NEC plants, thus showing an additive effect to low N priming in boosting fruit production. Pepton maintained fruit quality in terms of sugar accumulation, total acidity and the contents of carotenoids, vitamins C and E. Pepton-related improvement in fruit production seemed to be related, at least partially, to an increased accumulation of cytokinins and photosynthetic pigments in leaves, which might favor vegetative vigor and ultimately fruit yield. In conclusion, Pepton application was effective in improving the yield of greenhouse tomatoes showing additive effect with low N priming, without negatively affecting fruit quality.

Pyroligneous Acid Increases Productivity and Nutritional Quality of Greenhouse Tomato

Pyroligneous Acid Increases Productivity and Nutritional Quality of Greenhouse Tomato

Effects of different concentrations of dissolved oxygen on the growth, photosynthesis, yield and quality of greenhouse tomatoes and changes in soil microorganisms

The effects of different concentrations of dissolved oxygen (DO; 4, 6, 7.5, and 9 mg L−1, control (CK), O1, O2, and O3, respectively) on the growth, photosynthesis, yield and quality of tomatoes and changes in soil microorganisms in a greenhouse were studied. These effects were evaluated for two years via a comparative design. (1) The effects of DO on the leaf area index (LAI), net photosynthetic rate (A), vitamin C (Vc) content, soluble sugar content, lycopene content, dry matter accumulation (Da), soil respiration rate, microbial carbon content, microbial nitrogen content, yield, irrigation water-use efficiency (IWUE), water-use efficiency (WUE), and soil oxygen content (SOC) were very significant (P < 0.01). (2) In 2018 (2019), the LAI, A, Vc content, soluble sugar content, lycopene content, Da, soil respiration rate, soil microbial carbon content and soil microbial nitrogen content in the O3 group increased by 25.59% (20.88%), 12.89% (36.14%), 38.39% (27.07%), 18.31% (47.67%), 18.45% (52.50%), 15.34% (12.58%), 48.33% (68.97%), 46.73% (64.38%), and 27.27% (36.84%), respectively, compared with those in the CK group. (3) In 2018 (2019), the yield, IWUE, WUE and SOC in the O3 group increased by 17.51% (15.09%), 17.48% (15.06%), 33.87% (34.97%) and 50.97% (53.34%), respectively, compared with those in the CK group. (4) The effects of aerated irrigation (AI) on the growth, photosynthesis, quality, biomass, yield, WUE and SOC of the tomatoes, as well as the soil microorganisms, were consistent such that O3 > O2 > O1 > CK, but their levels of significance differed slightly. When the DO of the irrigation water was increased, the SOC increased indirectly, the soil environment was improved, and the growth of the tomato plants increased. Moreover, these effects were also conducive to improved WUE and tomato quality and efficiency. This study provides a new irrigation model and a theoretical basis for the popularization of greenhouse crop cultivation.

Effects of irrigation quantity and biochar on soil physical properties, growth characteristics, yield and quality of greenhouse tomato

Considering the challenges faced by current agricultural industry, such as less cultivable land, lack of soil nutrient value, limited water resources, low yield and fruit quality (Appearance and nutritional values). Biochar application was found effective way to improve soil physical properties, consequently, yield and quality of tomatoes. Biochar at three levels: B0 (0 ton/ha), B1 (25 tons/ha) and B2 (50 tons/ha) with three levels of drip irrigation quantity: full irrigation T1 (1.4 pan evaporation Ep), moderate water deficit T2 (1.2 Ep) and severe water deficit T3 (1.0 Ep) were applied in greenhouse. Thus, nine treatments, i.e. T1B0, T1B1, T1B2, T2B0, T2B1, T2B2, T3B0, T3B1 and T3B2 were set. The effects of applied different levels of irrigation quantity and biochar on soil physical properties, crop growth, yield and fruit quality were observed. Increasing level of applied irrigation quantity and biochar could improve the physical properties of soil effectively: decreased, increased and varied the soil bulk density, porosity and 3-phase composition of soil respectively. It is found that increasing levels of applied irrigation quantity at B2 had good effects on bulk density, porosity and 3-phase proportion of soil, and best composition of 3-phase (solid and pores: liquid + gas were 33.68 % and 66.32 % respectively) at T2B2 was found. The growth rate, considering growth parameters: plant height and stem diameter, was increased by applying adequate level of irrigation quantity and biochar. The yield was found maximum at T1B2, which was increased by 30.92 % as compared to T1B0. For T3 level, biochar application increased tomato yield, as compared to B0 by 83.69 % and 176.60 % at B1 and B2 respectively. It is concluded that application of biochar under full and severe deficit irrigation level increased tomato yield effectively, but tomato growth could inhibit under moderate water deficit irrigation, caused a slight yield reduction.

Coupling fertigation and buried straw layer improves fertilizer use efficiency, fruit yield, and quality of greenhouse tomato

Inefficient and over use of nitrogen fertilizer and irrigation water are the severe issues with adverse economic and environmental impacts. In present study, the effect of buried straw layer coupled with fertigation was investigated on fruit yield, water use efficiency and quality of greenhouse-grown tomato for two consecutive years. A randomized block design with three factors; 1) straw: (SN; no straw and SW; with straw burial), 2) nitrogen: (N1; 225 kg ha−1 and N2; 180 kg ha−1 and 3) irrigation; (I1; 90% and I2; 70% of requirement) was established. The results showed that under lower nitrogen (N2) and irrigation levels (I2), the tomato yield was increased by 16.5% and 24.7% under buried straw layer treatment (SWN2I2) when compared to no straw treatment SNN2I2. However, under higher nitrogen (N1) and irrigation levels (I1), fruit yield was reduced by 45.8% and 28.6% under buried straw layer treatments (SWN1I1) when compared to no straw treatment SNN1I1 for two years respectively. The total soluble solids (°Brix), soluble sugar content, sugar-acid ratio (SAR) and vitamin C (VC) were all increased under SWN2I2 when compared with control treatment SNN1I1 during both seasons. The 3-way ANOVA indicated that the fruit quality was found more sensitive to buried straw layer and irrigation. However, SWN2I2 treatment increased WUE and FUE significantly under limited nitrogen and irrigation conditions. In addition, TOPSIS analysis ranking indicated that SWN2I2 has the best fruit quality when compared to control treatment (SNN1I1). It was concluded that straw burial could alleviate the stress developed by limited irrigation water and fertilizer for improving fruit yield and quality in the greenhouse-grown tomato.

Performance of greenhouse tomato (Lycopersicon esculentumMill.) under compost and other mulch types

This study was conducted at The Princess Tasneem Bent Ghazi Technological Research Station, Al-Balqa' Applied University during the 2013-2014 growing season. The purpose of this study is to assess the impact of different soil mulches on field performance, yield and fruit quality of greenhouse tomato (Lycopersicon esculentum M.) under drip irrigation system. The experiment evaluated seven types of mulch treatments including black plastic, tuff gravel, clear plastic, compost, crushed stone, shredded wood, and the control. A randomized complete block design with three replicates was used. Different mulch types showed significant effects on vegetative growth, early, medium, late harvest, and total yields of the tomato fruits. Compost mulch resulted in the highest total yield. Higher early and medium yields were obtained using black and clear plastic mulches, respectively. In addition, larger fruits were obtained by applying compost mulch. Tomato fruit cracking was also affected in different ways depending on the mulch types used in this study.

Effects of Different Irrigation Amount on Yield and Quality of Greenhouse Tomatoes

In order to determine the proper irrigation amount of summer tomatoes,taking drip irrigation in green house,5 irrigation volume including 990 m3/hm2、1485 m3/hm2、1980 m3/hm2(CK)、2475 m3/hm2、2970 m3/hm2were set,and the effects of different irrigation amount on the yield and quality of tomato in greenhouse were studied. The results showed that with the increase of irrigation amount,the soluble solid content,titratable acid content,Vc content and irrigation water use efficiency of tomato decreased. In treatment T1, T4, T5 ,yield decreased by 26.3%, 6.5%, 15.8%. In treatment T2 , the yield decreased by 1.9%,while the irrigation water use efficiency increased by 20.8%,and the soluble solids content,titratable acid content and Vc content increased.It is concluded that the optimum irrigation amount is 1485 m3/hm2.

Analysis of gas exchange, stomatal behaviour and micronutrients uncovers dynamic response and adaptation of tomato plants to monochromatic light treatments

Light spectrum affects the yield and quality of greenhouse tomato, especially over a prolonged period of monochromatic light treatments. Physiological and chemical analysis was employed to investigate the influence of light spectral (blue, green and red) changes on growth, photosynthesis, stomatal behaviour, leaf pigment, and micronutrient levels. We found that plants are less affected under blue light treatment, which was evident by the maintenance of higher A, gs, Tr, and stomatal parameters and significantly lower VPD and Tleaf as compared to those plants grown in green and red light treatments. Green and red light treatments led to significantly larger increase in the accumulation of Fe, B, Zn, and Cu than blue light. Moreover, guard cell length, width, and volume all showed highly significant positive correlations to gs, Tr and negative links to VPD. There was negative impact of monochromatic lights-induced accumulation of Mn, Cu, and Zn on photosynthesis, leaf pigments and plant growth. Furthermore, most of the light-induced significant changes of the physiological traits were partially recovered at the end of experiment. A high degree of morphological and physiological plasticity to blue, green and red light treatments suggested that tomato plants may have developed mechanisms to adapt to the light treatments. Thus, understanding the optimization of light spectrum for photosynthesis and growth is one of the key components for greenhouse tomato production.

Effects of various kinds of potassium fertilizers on the yield and quality of greenhouse tomatoes

The effects of KCl, K&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; and KNO~ on the yields of greenhouse tomatoes variety 'Revermun' cultivated on a peat substrate were examined. On the basis of fruit yield, dry weight content in the fruit and the content of K, Ca, Mg, Cl, S-SO&lt;sub&gt;4&lt;/sub&gt; in the soil and of N, P, K, Ca, Mg, Cl, S-SO&lt;sub&gt;4&lt;/sub&gt;, Fe, Cu, Mn, Zn, Mo in leaf stalks it was found that KCl is the best form foir fertilizing greenhouse tomatoes cultivated on peat. No adverse effects of chlorine at concentrations of 1500 mg Cl/liter peat and 6,0% Cl in the dry mass of tomato leaves were observed.

The Influence of Fertilization on Greenhouse Tomatoes Cultivated in Peat Bags System

Important factors to be considered for growing tomatoes in order to obtain high and safety yield are variety, system of culture and fertilization. To establish how the fertilization managing can influence both yield and quality of greenhouse tomatoes grown on peat bags system, different doses and types of fertilization (basic and additional) were studied in this experiment. Two Dutch cultivars (Cronos F1 and Menhir F1) with high yield potential were used. Cronos F1 recorded the best early yield (5.87 kg·m -2 ) and Menhir F1 the best total yield (13.06 kg·m -2 ). Foliar fertilization, done with a high K ratio fertilizer (10:5:26), once weekly applied, determined distinct significant efficiencies of early yield and significant efficiencies of total yield. Vitamin C, acidity and total sugar content in the fruit increase with foliar fertilization. None of the nitrate or nitrite values over passed the accepted limits of permission for greenhouse tomatoes. Greenhouse tomatoes grown on peat bags system allows to increase early and total yield in comparison with conventional crop in soil. Because bags contain only a small volume of growth medium, they offer much lower water holding capacity and much lower buffering capacity than most soils regarding both major and minor elements. Therefore it is necessary to monitor continually the nutrient availability in the substrate and to adjust accordingly the composition of feed applied to it. The quantity of nutrients which should be applied also depends on the yield potential of the cultivar and growth conditions. Tomatoes need a continuous and steady supply of nutrients through additional fertilization throughout their life cycle because their vegetative and reproductive stages overlap. Since many experiments have not revealed real differences between the product quality of vegetables grown in soil or hydroponically (Schnitzler and Gruda, 2003) soilless culture in greenhouse may be an alternative to soil culture for high-value vegetable crops including tomatoes. Better tomato fruit quality can be obtained by fertilization measures such as an increase in the concentration of the nutrient solution, or a reduction of nitrate application rates. It is also necessary to adopt appropriate nutrient management practices (use of slow- release fertilizers, split applications, combining of radicular and foliar fertilization) which help to supply nutrients in adequate quantities to just meet crop demand and minimize losses, thus increasing the nutrient use efficiency. The objective of the present study was to evaluate two greenhouse tomato hybrids grown in bags on organic substrate (mostly composed from brown peat) in order to establish how fertilization managing can influence yield and chemical properties of fruit.

Effect of Degree and Duration of Shade on Quality of Greenhouse Tomato

Some amount of shade may be optimal to produce high-quality tomatoes in a greenhouse during summer months in the northeast United States. Simultaneous comparisons were made among greenhouse sections that were either not shaded or covered with reflective aluminized shadecloth that attenuated 15%, 30%, or 50% of direct sunlight. The shadecloth was applied at the start of warm weather in June. The houses were shaded for the rest of the summer, and fruit was picked until late August. Total yield decreased linearly with increasing shade, but there was no significant difference among shade treatments in marketable yield. The fraction of fruit that was marketable was greatest for plants grown under 50% shade. This fraction was 9% greater than in a greenhouse with no shade in 2003 and 7% greater in 2004 and 2005. Cracked skin was the defect most affected by shade. Among sensitive cultivars, up to 35% of the fruit produced in greenhouses with no shade had cracked skin, whereas in greenhouses covered with 50% shade, only 24% to 26% of the tomatoes had cracked skin. There was no consistent trend for shade density in the fraction of fruit with green shoulder, blossom end rot, or irregular shape. The effect of shade increased with duration of shading. There was no effect of 50% shade compared with no shade on total yield within 20 days, but yield decreased by 20% in the interval from 25 to 45 days after shading and by 30% after 50 or more days of shading in 2005. Marketable yield only decreased after more than 45 days of shading for cultivars that were not sensitive to cracked skin or uneven ripening. Shade decreased fruit size over the entire season only in 2003. In general, shading increased the fraction of marketable tomato fruit without affecting fruit size.

Effect of Shade on Quality of Greenhouse Tomato

Shading a greenhouse increased the fraction of tomatoes that were marketable, and the marketable yield, in a comparison of greenhouse tomato yields across years, in some of which the greenhouses were shaded. In 2003, the yield and quality of greenhouse tomatoes were compared directly when grown in spring and summer in Connecticut in identical greenhouses that differed only in the degree of shade. Each half of four greenhouses was either unshaded or shaded using reflective aluminized shade cloth rated to reduced light transmission by 15%, 30%, or 50%. Each shade treatment was repeated in two houses. Tomatoes were germinated in February and transplanted in March The houses were shaded when fruit began to ripen in early June. Picking continued through August. The effect of shade on total yield developed gradually. Yields in June were unaffected by shade, but in August yield under no shade was about 30% higher than under 50% shade. In contrast, there was an immediate effect of shade on fruit size. Fruit picked in June from plants under 50% shade was 16% smaller than from plants grown under no shade. This difference declined later in the season, to 6 and 9%, in July and August respectively. The highest yield of marketable fruit in 2003 was picked from houses under no shade, but this was only 10% more than picked from the houses under 50% shade. Shade increased the fraction of marketable fruit, from 54% under no shade to 63% under 50% shade. Certain defects were decreased by shade. For instance the fraction of fruit with cracked skin was decreased from 33% to 25%. In general, effects on fruit quality varied linearly with the degree of applied shade.

The effect of boron levels in nutrient solutions on fruit production and quality of greenhouse tomatoes

Insufficient fruit set of tomatoes owing to poor pollination in low cost greenhouses is a problem in South Africa, as bumblebee pollinators may not be imported. Since sub-optimum boron (B) levels may also contribute to fruit set problems, this aspect was investigated. Greenhouse tomatoes were planted in acid-washed river sand. Four nutrient solutions with only B at different levels (0.02; 0.16; 0.32 and 0.64 mg l-1) were used. Leaf analyses indicated that the uptake of Ca, Mg, Na, Zn and B increased with higher B levels. At the low B level, leaves were brittle and appeared pale-green and very high flower abscission percentages were found. Fruit lacked firmness at the low B level and this problem worsened during storage. At the 0.16 mg kg-1 B-level, fruit set, fruit development, colour, total soluble solids, firmness and shelf life seemed to be close to optimum. The highest B-level had no detrimental effect on any of the yield and quality related parameters. However, using ‘Solubor’ as a source of B, high levels decreased soluble Mn concentrations in nutrient solutions, probably owing to the precipitation of insoluble MnO2. This was reflected in reduced leaf-Mn concentrations.

Effect of potassium magnesium chloride in the fertigation solution as partial source of potassium on growth, yield and quality of greenhouse tomato

The effect of partial replacement of KCl in the fertigation by KCl·MgCl 2 on growth, yield and quality of greenhouse tomato (cv. Durinta) was studied in a soil-less system. Forty-seven days after planting (DAP), three treatment solutions were applied to the plants using different K sources: (1) KNO 3, (2) KCl, and (3) KCl·MgCl 2+KCl (25%:75% in terms of K supplied). In both treatments 2 and 3, NH 4NO 3, Ca(NO 3) 2 and HNO 3 were added as source of N. Plant height and total chlorophyll were the highest in the KCl+KCl·MgCl 2 treatment. Leaf Mg content was significantly lower in the KCl treatment, whereas highest in the KCl+KCl·MgCl 2 treatment. Both KCl and KCl+KCl·MgCl 2 led to a significantly higher leaf Cl content as compared with the KNO 3 treatment, but no Cl toxicity was observed in either treatment. Total yield was not different among treatments. Fruit firmness and freshness of the calyx were significantly improved by KCl and KCl+KCl·MgCl 2, and the number of rotten and blotchy fruits were significantly reduced by both these treatments. KCl+KCl·MgCl 2 also led to significantly higher levels of glucose, Mg and dry matter content in the fruit. Lower NO 3 and higher Fe contents were measured in both treatments 2 and 3. Although KCl as sole K source showed lower foliar Mg level as compared to KNO 3, the use of the KCl in tomato fertigation improved tomato fruit appearance and qualities. However, 25% replacement of KCl by KCl+KCl·MgCl 2 increased the foliar Mg level and improved fruit qualities even further.

Influence of Drip Irrigation Schedule and Mulching Material on Yield and Quality of Greenhouse Tomato (Lycopersicon esculentum Mill. ‘Money Maker’)

Influence of Drip Irrigation Schedule and Mulching Material on Yield and Quality of Greenhouse Tomato (Lycopersicon esculentum Mill. ‘Money Maker’)

Heating Soil with Hot Air Improves Early Yield and Quality of Greenhouse Tomatoes

The soil within a greenhouse was heated by blowing hot air from a forced-air heater through drainage pipes buried beneath raised beds. This warmed the soil from 50F (10C) to 68F (20C) after 1 week of heating in mid-March. Soil in unheated beds did not warm to this temperature until May. The yield of tomato (Lycopersicon esculentum Mill.) planted in heated beds was higher than in unheated beds by 16% over the season in 1992, and by 14% as of early July 1993. The weight fraction of highest-quality fruit also were 11% greater in 1993. This simple method of soil heating involved negligible additional expense