Reducing of tomato physiological disorders by photoselective shade nets

Transcription

1 Reducing ORIGINAL of SCIENTIFIC tomato physiological PAPER disorders by photoselective shade nets Reducing of tomato physiological disorders by photoselective shade nets Lidija MILENKOVIĆ 1, Zoran S. ILIĆ 1, Ljubomir ŠUNIĆ 1, Radmila TRAJKOVIĆ 2, Nikolaos KAPOULAS 3, Mihal ĐUROVKA 4 1 Faculty of Agriculture, Priština-Lešak, Lešak, Serbia (e -mail: zoran_ilic63@yahoo.com) 2 Faculty of Natural Sciences and Mathematics, Department of Biology, Kosovska Mitrovica 3 Regional Development Agency of Rodopi, N Komotini, Greece 4 Faculty of Agriculture, University of Novi Sad, Novi Sad, Novi Sad, Serbia Abstract The aim of this study was to evaluate the influence of different colored shade nets (pearl, red, blue and black) with different relative shading (40% and 50% PAR) on yield and physiological disorders at open field tomato production in south part of Serbia (Aleksinac). Shading reduced the appearance of tomato cracking about 50% and eliminated sun scalds on tomato fruits and accordingly, increased the marketable tomato production by about 35% compared to nonshading conditions. Sunscald injury, cracked skin and blossom-end rot were the defects most affected by pearl and red nets with 40% shade. Key words: color nets, yield, defect, sun scald, cracking Introduction Global warming effects that are already setting in are likely to increase the incidence of tomato abiotic disorders as the climate changes. Causes of physiological disorders include genetic susceptibility, environmental factors, watering practices, nutrition, and cultural practices such as pruning and training. Netting is frequently used to protect agricultural crops from excessive solar radiation (Ilić et al., 2011), improving the thermal climate (Kittas et al., 2009), sheltering from wind and hail and exclusion of bird and insect-transmitted virus diseases (Teitel et al., 2008; Shahak et al., 2008). It is either applied by itself over nethouse constructions, or combined with greenhouse technologies (Shahak et al., 2004). Movable shade, applied only during sunny periods, should be less deleterious than constant shade. When mobile shade was applied under intense sunlight in Spain it increased marketable yield by 10%. Movable shade, applied only during sunny periods, should be less deleterious than constant shade (Adams et al., 2001). In Egypt, a 30 to 40% reduction in sunlight intensity seems to be optimum. Total yield decreased linearly with increasing shade, but there was no significant difference among shade treatments in marketable yield (Gent 2007). Physiological disorders are abnormalities in fruit color or appearance that are abiotic in origin. These abnormalities are often confused with damage from pathogens or insects (biotic damage). There are also a number of different names for many disorders (Peet, 2009). Physiological disorders are divided into groups: nutrient imbalances, especially between potassium and nitrogen or magnesium (blotchy ripening, greywall); calcium amount or movement into the fruit (gold fleck or speck, blossom-end rot); temperature extremes (catfacing, boat fruit, rough fruit, puffiness, sunscald); genetic predisposition (green or yellow shoulder) and watering (cracking, russeting, rain check, shoulder check), Peet, (2009). A high light intensity can lead to disorders in development and appearance of tomato fruit (Dorais et al., 2001). Sunscald injury and uneven ripening are two disorders brought on by direct effects of light on fruit. Sunscald injury of tomato fruit increased with irradiance and air temperature and their combined effects (Adegoroye and Jolliffe, 1987). The goal of the present two-year study was to evaluate, the influence of different colored shade nets on the plant development, yield and quality of tomato fruit. Proceedings. 47th Croatian and 7th International Symposium on Agriculture. Opatija. Croatia ( ) Section 4. Vegetable Growing, Ornamental, Aromatic and Medicinal Plants 419

2 Lidija MILENKOVIĆ, Zoran S. ILIĆ, Ljubomir ŠUNIĆ, Radmila TRAJKOVIĆ, Nikolaos KAPOULAS, Mihal ĐUROVKA Material and methods Tomato (Lycopersicon esculentum, cv. Amati F 1 ) has been tested in open field production during The experiments were performed at the experimental field located at village Moravac near Aleksinac, on the central area of south Serbia. The shading nets were mounted on a structure about 2.0 m in height over the plants same a screen-house. The shade nets were applied at the start of warm weather in early June. The plants were shaded for the rest of the summer, and fruit was picked until late August. A completely randomized block design was used, with four blocks assigned to each of four treatments (black, pearl, blue and red net) and control. Each treatment and block consisted of four rows of 20 plants. Plant density was 2.6 plants m -2. Plant material The plants were grown following the technique that is usually implemented by the local producers. Seedlings were transplanted on 5 of May. The shading nets were installed above the crop on 10 of June (35 days after transplanting) and the measurements were carried out until 5 of September. All plants were irrigated using drip irrigation. The tomatoes used in the study were harvested from the mature-pink stage. Net characteristics In order to test the effect of shading nets (colour and shading intensity), four different shading nets were used: the photoselective nets include colored-colornets (red, blue and black) as well as neutral-colornets (pearl) with shading intensity of 40% and 50% relative shading (calculated as photosynthesis active radiation-par) and were compared with the open field microclimate and production. Light interception by nets The effect of nets on the interception of light was measured annually as a percentage of total above canopy Photosynthetically Active Radiation (PAR), using a Ceptometer mod. Sun Scan SS1-UM-1.05 (Delta-T Devices Ltd Cambridge, UK) with a 64 sensor photodiode linearly sorted in a 100 cm length sword. Readings are in units of PAR quantum flux (μmol m -2 s -1 ). Solarimeter - SL 100 easy to use portable autonomous solarimeter that measures solar irrigation range from 1 W m 2 to 1300 W m 2. All spectral data were expressed as radiation intensity flux distribution in W m -2 nm -1. Weather Measurement Monthly meteorological data from May to September 2008 and 2009 from Aleksinac meteorological stations were used (Table 1). Table 1. Temperature and solar radiation during the growing season in Aleksinac Month TS TOD TX TM MSR RR RO May Jun July August September TS-mean monthly air temperature ( o C); TOD-temperature deviation from average ( o C); TX-mean daily temperature maximum for month ( o C); TM-mean daily temperature minimum for month ( o C); MSR, mean daily solar radiation (MJ/m 2 ); RRprecipitation amount (mm); RO-relative deviation of monthly precipitations amount from average. Statistical analysis Experiments were performed according to a randomized block desing (two factorial experiment). The data were analyzed by analysis of variance (ANOVA) followed by Tukey s HSD test, using the Statistica 6.1 software (Statsoft, Tulsa, OK, USA). All analyses were performed at a 95 % level of confidence (p<0.05). Results and discussion It was founded here that red and pearl shade nets significantly increased the total yield which was associated with both higher productivity (number of fruits produced per plant) and larger fruits (data not show). Tomato under 50% shadow had similar fruit yield in comparison with yield obtained from 40% color shade nets, except in black shade nets where yield were lowest than control. Plants grown under black color nets with 50% shadow had smaller yield for 8.7% than plants grown without nets-control. On average of two years, the total fruit yields (t ha -1 ) under the colored shade nets were higher by %, relative to the equivalent black shade net th Croatian and 7th International Symposium on Agriculture

3 Reducing of tomato physiological disorders by photoselective shade nets Figure 1. Effects of shading on tomato yield in screen-house (different color nets) and open field condition (control) Differences in yield between control and red or pearl color nets are even more pronounced for net house (27.3 and 28.1%). Our results showed that shading of tomato plants affected both fruit yield and quality. Total and marketable yields increased with shading levels of 40%, and decreased with increasing shading levels to 50% (Figure 1). Fruit cracking not only reduces fruit appeal and marketing, but can also increase fruit susceptibility to decay and shorten shelf-life. Affected areas may later develop Alternaria and Cladosporium rots. Tomato fruit quality for fresh consumption is determined by appearance (colour, shape, size, freedom from physiological disorders & decay) firmness, texture, dry matter and organoleptic (flavor) and neutraceptic (health benefit) properties (Dorais et al., 2001). Total and marketable yield increased with shading levels to 40% shading and then decreased with increasing shading levels (50%). The reduced total and marketable yields of un-shaded plants were probably due to high heat stress. Moderate shading (40%) of tomato may be an option to reduce heat stress conditions and extend the summer season toward the September. Similarly, in Egypt, a 30 to 40% reduction in sunlight intensity seems to be optimum. El-Gizawy et al. (1992) observed that the highest tomato crop production was obtained under 35% shading and increasing shading intensity decreased sun scald on fruits up to 100%. However, El-Aidy and El-Afry (1983) observed that the highest tomato production was obtained under 40% shading. Movable shade, applied only during sunny periods, should be less deleterious than constant shade (Adams et al., 2001). Possible cause of the decrease of cracked fruit by shading is a decreased fruit temperature by the shading treatments. The percentage of the total fruit production affected by the different physiological disorders, for the different shading nets and outside, is presented in Table 2. Table 2. Effects of shading on marketable yield and physiological disorders at open field and screen-house (different color nets) tomato production Marketable yield * Cracking Sun scald Blossom and root Puffiness Irregular shape Control open field % shade Pearl 87a 5a - 1a 5a 2a Red 86a 6ab - 1a 5a 2a Blue 83b 7b - 2ab 6b 2a Black 81b 7b - 3b 6b 3b 50% shade Pearl 81a 6a - 4a 6a 3a Red 80a 7ab - 4a 6a 3a Blue 76b 8b - 5b 8b 3a Black 74b 8b - 5b 9b 4b *Marketable yield represents percent of total yield ; Different letters in the same column indicate statistically significant differences (p ( 0.05) Section 4. Vegetable Growing, Ornamental, Aromatic and Medicinal Plants 421

4 Lidija MILENKOVIĆ, Zoran S. ILIĆ, Ljubomir ŠUNIĆ, Radmila TRAJKOVIĆ, Nikolaos KAPOULAS, Mihal ĐUROVKA A high light intensity can lead to disorders in development and appearance of tomato fruit (Dorais et al., 2001). The benefit of shade on quality in this case was due to less blossom end rot and cracked skin. Sunscald injury and uneven ripening are two disorders brought on by direct effects of light on fruit. Sunscald injury of tomato fruit increased with irradiance and air temperature and their combined effects (Adegoroye and Jolliffe, 1987). The benefit of shade on quality in this case was due to less blossom end rot and cracked skin (Lorenzo et al. 2003). Possible cause of the decrease of cracked fruit by shading is a decreased fruit temperature by the shading treatments. The percentage of the total fruit production affected by the different physiological disorders, for the different shading nets and outside, is presented in Table. 2. It can be seen that sun scald was eliminated under shading while tomato cracking, blossom end rot and puffiness were reduced to about 50% than that under open field. Sun scald is a common form of heat injury. When tomatoes are exposed to direct solar radiation, fruit temperature may increase by 10ºC or more above the ambient. When the temperature of an exposed fruit portion exceeds 40ºC, it becomes white and sunken (sunscald or sunburn). Tomatoes at the mature-green stage are especially susceptible. We have observed large increases in fruit cracking in greenhouse tomato production toward summer. Similarly, Peet and Willits (1995) also observed a linear increase of fruit cracking at the upper clusters of tomato fruit with high solar irradiance and fruit temperature. The light available to plants is mainly determined by the level of natural solar radiation. However, it can also be affected by the greenhouse cover material, supplemental lighting, shading/white-washing, plant density and canopy architecture management. In northern Europe, where light is a limiting factor, 1% light reduction has induced approximately 1% fruit yield loss, and thus the glass is the dominant greenhouse cover in greenhouse tomato production because of its higher light transmission (Cockshull et al., 1992). Therefore growers should learn to positively identify the various physiological disorders that occur in their agro-ecological zones/areas and be able to manipulate the environment and to use locally available resources /color shade nets to control particular disorders. Conclusions The yield and quality of tomatoes were affected by color shade nets, except at plants grown under black color nets with 50% shadow. The fraction of marketable fruit was greatest for plants grown under 40% shade. The highest percentages of puffy and blotchy ripening fruits were detected by plants grown under full sunlight and heavy shading (50%). Sunscald injury, cracked skin and blossom-end rot were the defects most affected by pearl and red nets with 40% shade. References Adams, S.R., Valdes, V.M., Cave, C.R.J., Fenlon, J.S. (2001). The impact of changing light levels and fruit load on the pattern of tomato yields. J. Hort. Science 76: Adegoroye, A.S., Jolliffe, P.A. (1987). Some inhibitory effects of radiation stress on tomato fruit ripening. J. Science Food Agric. 39: Cockshull, K.E., Graves, C.J., Cave, C.R.J. (1992). The influence of shading on yield of greenhouse tomatoes. Journal of Horticultural Science 67: Dorais, M., Papadopoulos, A.P., Gosselin, A. (2001). Greenhouse tomato fruit quality. Hort. Rev. 26: El-Aidy F., El-Afry M. (1983). Influence of shade on growth and yield of tomatoes cultivated during the summer season in Egypt. Plasticulture. 47: 2-6. El-Gizawy A.M., Abdallah M.M.F., Gomaa, H.M., Mohamed, S.S. (1992). Effect of different shading levels on tomato plants 2. Yield and fruit quality. Acta Hort. 323: Ilić, Z., Milenković, L., Đurovka, M., Kapoulas, N. (2011). The effect of color shade nets on the greenhouse climate and pepper yield. 46 th Croatian and 6 th International Symposium on Agriculture. Opatija, Croatia. Symposium Proceedings, pp Gent, M.P.N. (2007). Effect of degree and duration of shade on quality of greenhouse tomato. HortScience. 42: Peet, M.M., Willits, D.H. (1995). Role of excess water in tomato fruit cracking. HortScience. 30: Kittas, C., Rigakis, N., Katsoulas, N., Bartzanas, T. (2009). Influence of shading screens on microclimate, growth and productivity of tomato. Acta Hort. 807: th Croatian and 7th International Symposium on Agriculture

5 Reducing of tomato physiological disorders by photoselective shade nets Lorenzo, P., Sanchez-Guerrero, M.C., Medrano, E., Garcia, M.L., Caparros, I., Giminez, M. (2003). Effect on microclimate, water use efficiency, and yield of a tomato crop grown under different salinity levels of the nutrient solution. Acta Horticulture. 609: Mitchell, J.P., Shennan, C., Grattan, S.R.; May, D.M Tomato fruit yields and quality under water deficit and salinity. Journal of American Society for Horticultural Science 116, Peet, M.M. (2009). Physiological disorders in tomato fruit development. Acta Horticulturae. 821: Shahak, Y., Gussakovsky, E.E., Gal, E., Ganelevin, R. (2004). ColorNets: Crop protection and lightquality manipulation in one technology. Acta Hort. 659: Shahak, Y. (2008). Photoselective Netting for Improved Performance of Horticultural Crops. A Review of Ornamental and Vegetable Studies Carried in Israel. Acta Horticulturae.770: Teitel, M., Liron, O., Haim, Y., Seginer, I. (2008). Flow through inclined and concertina-shape screens. Acta Horticulturae. 801: Acknowledgements This study is part of the TR project entitled,,organic agriculture: Improving the production of fertilizer application, and bio-preparate of biological protection,, financially supported by the Ministry of Science and Technological Development, Republic of Serbia. sa2012_0414 Section 4. Vegetable Growing, Ornamental, Aromatic and Medicinal Plants 423