P. Szuvandzsiev

Effect of irrigation on yield parameters and antioxidant profiles of processing cherry tomato

A two-year (2010 and 2011) open field experiment was conducted to study the effect of drip irrigation and seasonal variation on the yield parameters and main bioactive components, carotenoids (mainly all trans, cis lycopene, and β-carotene), polyphenols (chlorogenic acid, caffeic acid, gallic acid, quercetin, rutin, naringin, etc.), and tocopherols of processing Strombolino F1 cherry tomatoes. The irrigated plants (STI) gave a higher marketable yield (61% and 101% respectively), and rain fed plants showed a yield loss. Water supply had a strong positive (R2=0.98) effect on marketable yield in 2011, but weak (R2=0.69) in 2010. In both years, the antioxidant concentration (all carotenoids, total polyphenols, tocopherols) showed a decrease with irrigation. Water supply affected the composition of carotenoids to a considerable extent. The optimum water supply treatment gave a lower proportion of lycopene than the rain fed control (STC) treatment. We observed significant negative correlation between rutin concentration and irrigation. The α-tocopherol concentration was significantly higher in STC treatments. Irrigation negatively influenced antioxidant concentrations of cherry tomato fruits, but higher yield could account for the concentration loss of individual fruits by higher antioxidant production per unit area.

Estimation of antioxidant components of tomato using VIS-NIR reflectance data by handheld portable spectrometer**

Abstract Processing tomato production represents an important part of the total production of processed vegetables in the world. The quality characteristics of processing tomato, important for the food industry, are soluble solids content and antioxidant content (such as lycopene and polyphenols) of the fruit. Analytical quantification of these components is destructive, time and labour consuming. That is why researchers try to develop a non-destructive and rapid method to assess those quality parameters. The present study reports the suitability of a portable handheld visible near infrared spectrometer to predict soluble solids, lycopene and polyphenol content of tomato fruit puree. Spectral ranges of 500-1000 nm were directly acquired on fruit puree of five different tomato varieties using a FieldSpec HandHeld 2™ Portable Spectroradiometer. Immediately after spectral measurement, each fruit sample was analysed to determine soluble solids, lycopene and polyphenol content. Partial least square regressions were carried out to create models of prediction between spectral data and the values obtained from the analytical results. The accuracy of the predictions was analysed according to the coefficient of determination value (R2), the root mean square error of calibration/ cross-validation.

Effect of coloured shade nets on some nutritional characteristics of a kapia type pepper grown in plastic tunnel

Sweet pepper is the most important vegetable crop of the Hungarian greenhouse industry. Production of red coloured cultivars, having very high nutritive value, is getting popular recently. Shading of plastic tunnels is a common practice in Hungary, but research about its effects on the nutritional characteristics of sweet pepper has just started. The objective of this study was to investigate the effect of different shading methods (shading paint, white, green, yellow and red coloured shade nets) on some nutritional characteristics of a red coloured kapia type pepper, under Hungarian climatic conditions cultivated in unheated walk-in plastic tunnels. Shade net colour slightly affected radiation and hence temperature conditions of the tunnels; especially ratio of supra-optimal temperature values (32 °C <) was changed. Dry matter content was not influenced by shading method, in contrary to sampling time which had a significant effect on this parameter. Vitamin C and total polyphenol contents were affected by both of these factors and also by their interaction; shading effect on these phytonutrients changed with harvest times. However, total carotenoid content was affected just by this latter factor. Heat stress, higher ratio of supra-optimal temperature values, increased total polyphenol concentration and decreased total carotenoid content. In overall, white shade net resulted sweet peppers with the best nutritive quality, but harvest time had a more pronounced effect on content of nutritive constituents than shade net colour.