Quantitative and Qualitative Characteristics of Two Tomato Cultivars in Autumn Cultivation as Affected by Different Greenhouse Covers

Choosing the best covering material for the greenhouse roof is a very important factor influencing the quantity and quality of light entering the greenhouse. Some vegetative and reproductive traits and biochemical characteristics of two tomato cultivars (‘Synda’ and ‘Melody’) grown in some greenhouse units roof-covered with four covering materials (glass, plastic, polycarbonate and corrugated polyethylene) were investigated for autumn cultivation in the Research Greenhouses of Ferdowsi University of Mashhad. This experiment was designed in a split plot (main-plot: greenhouse cover; sub-plot: cultivar) based on a completely randomized design. The highest to lowest radiation rates were recorded in corrugated polyethylene, glass, plastic and polycarbonate covers, respectively. The ANOVA results showed that vegetative, reproductive and biochemical traits were significantly affected by greenhouse cover, cultivar, or greenhouse cover × cultivar interaction. Raising the plant health index through increasing the stem diameter and decreasing plant length was influenced by the amount of the irradiation provided by greenhouse covers; it was significantly higher in the corrugated polyethylene and glass covers rather than the plastic and polycarbonate ones. The maximum numbers of days from transplanting to flowering stage were obtained in the corrugated and glass covers (35.5 and 35 days, respectively) for the ‘Synda’ cultivar, and in glass cover (32.2 days) for the ‘Melody’ cultivar. The lowest fruit ripening (60 days) was observed in the ‘Melody’ cultivar under the corrugated polyethylene cover, while the highest value (80.25 days) was recorded in ‘Synda’ cultivar under the polycarbonate cover. Fruit production was the highest in the ‘Synda’ cultivar under corrugated polyethylene (6503.6 g/plant) and glass (6337.3 g/plant) covers, while ‘Melody’ under plastic and polycarbonate covers (1314.2 and 1027.1 g/plant, respectively) showed the lowest amount. According to the results of this experiment, from an economic point of view, based on Net Present Value (NPV) and Internal Rate of Return (IIR) factors, the greenhouse cultivation of ‘Synda’ cultivar under glass cover is recommended in Mashhad climatic conditions.