اثرات تاريخ كاشت، زمان آبياري و كاربرد گياهان پوششي بر رشد و عملكرد زعفران (Crocus sativus L.)

(Effects of Planting Dates, Irrigation Management and Cover Crops on Growth and Yield of Saffron (Crocus sativus L

به منظور بررسي اثرات زمان‌هاي كاشت بهاره، تابستانه و پاييزه و نيز مديريت آبياري و استفاده از گياهان پوششي، بر ويژگي هاي رشد و عملكرد گياه دارويي زعفران (Crocus sativus L.) آزمايشي در مزرعه تحقيقاتي دانشكده كشاورزي دانشگاه فردوسي مشهد در سال‌هاي زراعي 89-1388 و 90-1389، به صورت كرت هاي دوبار خرد شده در قالب طرح پايه بلوك‌هاي كامل تصادفي با سه تكرار اجرا شد. فاكتورهاي آزمايشي عبارت بودند از: تاريخ كاشت بهاره، تابستانه و پاييزه زعفران به عنوان فاكتور اصلي (اول خرداد ماه، اول مرداد ماه و اول مهر ماه)، مديريت آبياري به عنوان فاكتور فرعي (انجام آبياري و عدم انجام آبياري پس از هر تاريخ كاشت) و كاربرد گياهان همراه در سال دوم آزمايش به عنوان فاكتور فرعي فرعي [شبدر ايراني (Trifolium resopinatum L.)، خلر (Lathyrus sativus L.) و شاهد]. نتايج نشان داد كه با تأخير در كاشت بنه‌ها از اول خرداد به اول مهر، شاخص‌هاي كمي زعفران به طور قابل ملاحظه¬اي كاهش پيدا كرد و شدت كاهش در سال دوم آزمايش به مراتب بيشتر بود. بيشترين عملكرد گل در تاريخ كاشت مرداد ماه (به ترتيب 28 و 98 كيلوگرم در هكتار براي سال‌هاي اول و دوم آزمايش) و كمترين آن در تاريخ كاشت مهر ماه (به ترتيب 18 و 34 كيلوگرم در هكتار براي سال‌هاي اول و دوم آزمايش) به دست آمد. كاشت زعفران در تاريخ اول مرداد ماه موجب بهبود سرعت گل‌دهي و كاهش نسبي سرعت ظهور برگ گرديد. عدم آبياري پس از كاشت باعث افزايش شاخص‌هاي كمي زعفران شد؛ به طوري كه عملكرد گل در تيمار انجام آبياري پس از كاشت در سال اول نه و در سال دوم 43 كيلوگرم در هكتار و براي تيمار عدم انجام آبياري در سال‌هاي اول و دوم به ترتيب 37 و 78 كيلوگرم در هكتار بود. بيشترين تعداد گل در هكتار (480000 گل در هكتار) و نيز بيشترين درصد بنه‌هاي گل دهنده (100 درصد) در سال دوم آزمايش و در تيمار تاريخ كاشت خرداد ماه و عدم انجام آبياري پس از كاشت به دست آمد. كاربرد گياهان پوششي به خصوص خلر تا حدودي باعث بهبود ويژگي‌هاي رشد و عملكرد زعفران گرديد؛ به طوري كه استفاده از اين گياه پوششي، عملكرد گل و كلاله را در مقايسه با شاهد حدود دو درصد افزايش داد. همچنين بيشترين سرعت گل‌دهي و كمترين سرعت ظهور برگ در تيمارهاي تاريخ كاشت خرداد ماه، عدم انجام آبياري پس از كاشت و كاربرد گياه پوششي خلر مشاهده شد.

Introduction Saffron as a winter active plant with low water requirement is the most strategic medicinal plant in arid and semi-arid parts of Iran. This slow-growing plant has narrow leaves and no aerial stem, hence weeds can be overcome it. Moreover, because of its root and canopy structure an important part of different resources is not used by this low input crop. Therefore, the use of associated crops could be an effective way for increasing resources use efficiencies (Koocheki et al., 2016). Appropriate corm planting date is another important factor that affects saffron growth and yield. Results of some studies show that late spring is the best time for corm planting (Ghasemi-Rooshnavand, 2009; Koocheki et al., 2016). In addition, irrigation management has been evaluated in some studies, but irrigation immediately after corm planting has not been investigated previously. Therefore, the aim of this study was to investigate the effect of irrigation management, planting date and the use of some companion crops on flowering of saffron during two growth cycles. Materials and methods This experiment was carried out as a split-split plot experiment based on a Randomized Complete Block Design with three replications at Research Station, Ferdowsi University of Mashhad, Iran in 2009-2011. Experimental factors included: planting date of saffron as main factor (first of June, first of August and first of October, 2009), the irrigation management as sub factor (irrigation and no irrigation after each planting date) and the companion crops as sub-sub factor [Persian clover (Trifolium resupinatum), Bitter vetch (Lathyrus sativus) and control). Corm planting was done in 10×25 cm distances with 12 cm depth. In the second year irrigation was done again in the plots which were irrigated after planting in the first year at the same previous dates. Companion crops were sown after first flower picking (November, 2009), then their residue were returned to the soil in coming spring (May, 2010). Therefore, data were analyzed as split-plot in the first year and split-split-plot in the second year. Data analysis was done using SAS 9.1 and means were compared using Duncan multiple range test in 5% level of probability. Results and discussion Results showed that most growth and flowering indices of saffron were significantly affected by experimental factors. Quantitative indices of saffron were decreased considerably by delaying in planting date in both studied years. The highest flower yield was obtained in June planting date (28 and 98 kg.ha-1 in 2009 and 2010, respectively), while the lowest was shown in October planting date (18 and 34 kg.ha-1 in 2009 and 2010, respectively). Enhanced growth and yield of saffron in spring planting date is because of real dormancy stage of corms in this time. All studied indices were superior in no-irrigated treatments after planting in both studied years. The flower yield was 9 and 43 kg.ha-1 in 2009 and 2010 in irrigated treatments, respectively, while these values were 37 and 78 kg.ha-1in 2009 and 2010 in no-irrigation treatment, respectively. It has been reported that irrigation during the creation of the primary leaves in the corm buds is negative, while irrigation after this period and simultaneous with the beginning of primary reproductive organs creation is suitable for saffron flowering. The application of cover crops improved partially the quantitative indices of saffron, particularly in Bitter vetch treatment. In addition, the highest flowering rate and the lowest leaf appearance rate were observed in June planting date, no-irrigation and Bitter vetch cover crop treatment. The positive effects of short-growth cycle companion crops on saffron is related to improvement of soil physical, biological and chemical properties, soil temperature regulation, prevention from nutrient leaching, N-fixation by Fabaceae species and help to weeds control. Conclusion In total, saffron corm planting few days after the falling leaves in spring, no-irrigation after corm planting, avoidance from untimely summer irrigation and the use of appropriate winter cover crops are good strategies for saffron production.