Effects of Weed Management Treatments and Cover Crops as Winter Plating on Weed Population and Yield of Two Cultivars of Tomato

Introduction Weeds are one of the major reducing factors in tomato production. Cover crops have several features that can inhibit germination and decline emergence and establishment of weeds. The aim of this research was to investigate weed control by using winter cover crop species in production of tomato crops. Materials and Methods The experiment was conducted as split plot based on a randomized complete block design at Sabouri Field, Khorasan Razavi Agricultural and Natural Resources Research and Education Center during 2017-2018. Four winter cover crops (WCC) [such as chickling pea (Lathyrus sativus), hairy vetch (Vicia villosa), fenugreek (Trigonella foenum-graecum) and rye (Secale cereale)], irrigation (tilled soil without WCC) and control (tilled soil without irrigation) were considered as main factor and sub plots were two tomato cultivars (8320 and 6515 from FALAT Co.). WCC were converted into mulches in spring. Studied criteria were relative density, density and dry weight of weeds per unit area and number (in three stages such as 30 days after planting time, 50 days after planting time and before planting time) and fruit yield and Brix index in three ripening stages. Results and discussion The results showed that species of weeds controlled varies widely between WCCs. The minimum density and dry weight of weeds were belonged to hairy vetch and rye and the maximum was for control. Hairy vetch and rye are allelopathic with better efficacy against annual dicots than grasses. The simple and interaction effect of WCC and cultivar were significant on fruit number, fruit yield and Brix index. The highest and the lowest yield for the first, second and third ripening stages were observed in hairy vetch and control, respectively. Total yield for 6515 cultivar was 15 percent higher than 8320 cultivar. The highest and the lowest fruit numbers for the first, second and third ripening stages were related to hairy vetch (with 75.31, 37.78 and 22.3 fruits.m-2) and control (with 54.33, 22.78 and 8.85 fruits.m-2), respectively. Brix index for 8320 cultivar was higher than 6515 cultivar. Conclusion In general, annual, biennial or perennial weeds are suppressed by WCCs. This research indicate that WCCs could be used successfully in integrated weed management to decline weed infestation in tomato production.