تاثیر نیتروژن و تراکم بوته بر صفات مورفولوژیکی و اجزای عملکرد کاسبرگ چای ترش (hibiscus sabdariffa l.) در شرایط آب و هوایی ایرانشهر

به منظور بررسی تاثیر سطوح کود نیتروژن و تراکم بوته بر صفات مورفولوژیکی، عملکرد و اجزای عملکرد کاسبرگ چای ترش در منطقه ایرانشهر آزمایشی به‌صورت کرت های خردشده و در قالب طرح بلوک های کامل تصادفی با و 3 تکرار در سال 1393 در ایرانشهر انجام شد. در این تحقیق نیتروژن در چهار سطح (صفر، 100، 200 و 300 کیلوگرم نیتروژن در هکتار) به‌عنوان فاکتور اصلی و تراکم بوته در چهار سطح (5، 6.7، 10 و 20 بوته در مترمربع) به‌عنوان فاکتور فرعی مورد مطالعه قرار گرفت. نتایج نشان داد که با افزایش مصرف نیتروژن از صفر به 300 کیلوگرم در هکتار، قطر ساقه، تعداد انشعابات ساقه اصلی، تعداد میوه در بوته، تعداد میوه در مترمربع، عملکرد خشک کاسبرگ و عملکرد بیولوژیک به‌طور معنی داری و به ترتیب 15.8، 135.8، 104.7، 104.4، 108.8 و 30.5 درصد افزایش پیدا کرد. همچنین با افزایش تراکم از 5 به 20 بوته در مترمربع، قطر ساقه، تعداد انشعابات ساقه اصلی و تعداد میوه در بوته به‌طور معنی داری و به ترتیب 24.1، 76.6 و 37.3 درصد کاهش یافت، هرچند که تعداد میوه در مترمربع (125.6 درصد)، عملکرد خشک کاسبرگ (105.7 درصد) و عملکرد بیولوژیک (88.5 درصد) به‌طور معنی داری افزایش یافت. به‌طورکلی بر اساس نتایج این تحقیق کاربرد 300 کیلوگرم نیتروژن در هکتار و تراکم 20 بوته در مترمربع برای زراعت چای ترش در ایرانشهر پیشنهاد می گردد.

Effect of nitrogen and plant density on morphological traits and yield components of roselle (Hibiscus sabdariffa L.) in Iranshahr Climatic Conditions

Introduction Roselle is the English name for Hibiscus sabdariffa L. that is an annual or perennial medicinal plant. Roselle is specific to the warm and indigenous climate of Africa (Rahbarian et al., 2011). Roselle is one of the most important crop plants due to its medicinal properties and use in local and industrial foods (Sanoussi et al., 2011) in some countries. Also, its leaves as edible vegetable and its seeds have been used as enhancers and a rich source of protein (Maksoud and Hosni, 1997). Sepal is the most important part of the plant that can be green, red or dark red and in traditional medicine use to treat hypertension, liver lesions, cancer, fever, and inflammatory diseases. Nutrients, including nitrogen, have effects on vegetative and reproductive growth and economical yield of medicinal plants. Moreover, nitrogen affect on quantity and quality of its ingredients. Plants’ need for this nutrient varies according to plant type, climatic and field conditions, including plant density per unit area. Proper plant density is one of the most important factors affecting the growth and production of medicinal plants and is an effective factor in achieving optimum yield through maximum use of light and other resources (Omidbeigi and Hasani Malayeri, 2007). Materials and Methods The experiment was carried out in a farm located 6 km east of Iranshahr near IranshahrAbtar road with 60 degrees 45 minutes east longitude and 27 degrees 13 minutes north latitude with a height of 580 meters above sea level in 2014. This research was conducted as splitplot experiment on the basis of a randomized complete block design with three replications. In this research nitrogen set as main factor with four levels (0, 100, 200 and 300 kg N ha1) and plant density set as sub factor with four levels (5, 6.7, 10 and 20 plants per m2). The studied traits were plant height, number of branch per main stem, stem diameter, fruit length, number of fruit per plant, number of fruits per m2, dry weight of sepal in fruit, dry yield of sepal, biological yield and harvest index of sepal. In the end, all data were analyzed by MSTATC statistical software and means were compared by Duncan multiple range test at 5% level. Results andDiscussion Analysis of variance revealed that number of branch per main stem, number of fruits per plant, number of fruits per m2 and biological yield were significantly influenced by simple and interaction effects of nitrogen and plant density. Also, stem diameter and dry yield of sepal were significantly influenced by simple effects of nitrogen and plant density. Means comparison showed that increasing of nitrogen application from 0 to 300 kg N ha1, stem diameter, branches number of main stem, fruit number per plant, fruit number per m2, dry yield of sepal and biological yield significantly increased by 15.8, 135.8, 104.4, 108.8 and 30.5%, respectively. Moreover, increasing of density from 5 to 20 plants m2, stem diameter, branch number of main stem and fruit number per plant significantly decreased by 24.1, 76.6 and 37.3% respectively, but fruit number per m2, dry yield of sepal and biological yield significantly increased by125.6, 105.7 and 88.5%, respectively. It seems that the reason of significant increase in number of fruit per m2 and sepal yield per unit area with increasing application of nitrogen fertilizer can be development of shoots and increasing branch number thus more uptake of sunlight and finally the assimilates production in the plant. Also, significant increase in dry yield of sepal with increasing plant density per m2 was mainly due to significant increase in number of fruits per m2. Conclusion In general, according to the results of current study, application of 300 kg N. ha1 and density of 20 plants m2 can be suggested for roselle cultivation in Iranshar, Iran.