تأثير گياه پوششي چاودار وماشك و بقاياي آن‌ها بر علف‌هاي‌هرز مزرعه، عملكرد و اجزاي عملكرد گندم

The effect of cover crop rye, hairy vetch and residuals on weeds, yield and yield components of wheat

به‌ منظور بررسي تأثير گياه پوششي و بقاياي آن بر علف‌هاي‌هرز مزرعه و عملكرد و اجزاي عملكرد گندم آزمايشي به صورت طرح اسپليت پلات در قالب بلوك‌هاي كامل تصادفي با 3 تكرار طي دو مرحله اجرا شد. در مرحله اول گياهان پوششي به مدت 45 روز تا اعمال مديريت بقايا سبز بودند. در مرحله دوم گندم پس از اعمال عامل اصلي در سه سطح شامل برگرداندن گياه پوششي، كف بر كردن گياه پوششي و سم پاشي كردن گياه پوششي كشت گرديد. نتايج اين آزمايش نشان داد كه قبل از اعمال مديريت بقايا در زماني كه گياهان پوششي سرپا بودند تيمار چاودار و مخلوط، به طور متوسط تراكم (60 درصد) و وزن خشك (87 درصد) علف‌هاي‌هرز برگ‌باريك كمتري نسبت به شاهد داشتند. بعد از مديريت بقايا، بيشترين و كمترين تراكم علف‌هاي‌هرز باريك‌برگ به ترتيب در تيمار كف‌بر و كاربرد علف‌كش وجود داشت. گياهان پوششي نسبت به شاهد، تراكم و وزن خشك علف‌هاي‌هرز برگ‌باريك را به طور معني‌داري در هر دو مرحله ظهور سنبله (به ترتيب 59 و 62 درصد) و رسيدگي گندم (60 و 68 درصد) كاهش دادند. با توجه به اثرات كاهشي گياهان پوششي و بقاياي آن‌ها در خاك بر تراكم و وزن خشك علف‌هاي‌هرز باريك‌برگ خصوصا به صورت مخلوط چاودار+ماشك (به ترتيب كاهش 72 و 75 درصد نسبت به شاهد) مي‌توان از گياهان پوششي حتي با يك دوره رويشي كوتاه براي كاهش جوانه‌زني و يا تاخير در سبز شدن علف‌هاي‌هرز و در نتيجه كاهش قدرت رقابتي آن‌ها در مديريت علف‌هاي‌هرز مزرعه گندم سود جست.

Cover crops and their residues can act as mulches or physical barriers by smothering weeds, suppressing weed seed germination and growth. In order to evaluation the effect of cover crops and their residues on weed management, wheat yield and yield components, an experiment was conducted in 2014- 2015 in two stages. Evaluations were performed in randomized complete block design as split plot. At the first stage, cover crops grew for 45 days as second factor involved rye, hairy vetch, mixed of rye- hairy vetch and control without cover crop. In the next stage, wheat has planted after residuals management as first factor (include incorporated residuals, mowed residuals and herbicide application). The results showed standing cover crops, before residuals management, rye and mixed treatments reduced density (as average 60%) and dry weight (87%) of grasses significantly rather than control treatment. After residue management, mowing and herbicide application had highest and least density of narrow weeds respectively. On both samplings, cover crops decreased intensively density and dry weight of grasses at the stages of booting (59 and 62% respectively) and maturity (60 and 68%) of wheat. During this study, cover crops and residuals management had no a negligible and consistent impact on density and dry weight of broad leaf weeds. Despite residuals management was not effective on yield components and yield. A significant impact of cover crops observed on some yield components of wheat. Among the cover crop treatments, rye- hairy vetch mix had highest number of spikelet per spike, main spike weight, spike weight per square meter and biological yield. The cover crop and residuals management interaction showed higher harvest index when rye-cover crop killed by herbicide and rye- hairy vetch mix treated by mowing. Since cover crops and also their residuals in soil declined severely density and biomass of narrow weeds especially as rye-hairy vetch mix (72 and 75 percent respectively), then cover crops appear to be profitable for weed management due to delay or decline weed germination and reduction of wheatweed competition ensued from it even for short time.