اثر حذف برگ بر ویژگی‌های کمّی و کیفی ارقام چغندرقند پاییزه در استان گلستان

در گیاهان، برگ‌ها، اصلی‌ترین محل دریافت تابش خورشیدی و تولید مواد فتوسنتزی هستند، به همین دلیل برآورد میزان کاهش عملکرد ناشی از بین رفتن برگ‌ها، نقش مهمی در مدیریت مزرعه دارد. به منظور بررسی اثر حذف اندام هوایی (برگ و دمبرگ) در مراحل مختلف رشد رویشی بر عملکرد و کیفیت ریشه چغندرقند، آزمایشی به صورت فاکتوریل در قالب طرح بلوک‌های کامل تصادفی با سه تکرار در ایستگاه تحقیقات کشاورزی و منابع طبیعی ورسن گرگان در سال زراعی 991398 اجرا گردید. عامل اول شامل 6 رقم تجاری چغندرقند پاییزه (5 رقم خارجی و رقم داخلی شریف) و عامل دوم شامل سرزنی در اردیبهشت‌ماه (مرحله میانی رشد)، سرزنی در خردادماه (مرحله نهایی رشد) و تیمار شاهد (عدم سرزنی) انجام شد. در پایان فصل رشد صفات کمّی و کیفی ریشه اندازه‌گیری شدند. نتایج نشان داد ارقام چغندرقند در صفات درصد قند ناخالص (عیار)، قند خالص، سدیم، پتاسیم، ضریب استحصال شکر و قند ملاس اختلاف معنی‌داری از خود نشان دادند؛ ولیکن از نظر صفات نیتروژن مضره و الکالیته بین ارقام اختلاف معنی‌داری مشاهده نشد. سرزنی چغندرقند باعث کاهش درصد قند، نیتروژن و عملکرد ریشه و افزایش میزان الکالیته و پتاسیم ریشه گردید. بیشترین ضایعات عملکرد ریشه زمانی که برگ چغندرقند در مراحل میانی رشد (اردیبهشت ماه) حذف شدند به‌دست آمد، به‌طوری‌که کاهش عملکرد ریشه در سرزنی اردیبهشت‌ماه نسبت به سرزنی خردادماه بیشتر تحت تاثیر قرار گرفت. در مجموع، مرحله‌ای از رشد گیاه که حذف برگ صورت می‌گیرد و فاصله آن تا زمان برداشت بر عملکرد و خواص کیفی چغندرقند موثر می‌باشد.

Effect of Leaf Removal on Quantitative and Qualitative Characteristics of Autumn Sugar Beet Cultivars in Golestan Province

Introduction  Sugar beet, scientifically known as Beta vulgaris L, is allogamous, diploid, biennial plant of the spinach genus that is cultivated to produce storage roots. The growth period of sugar beet, depending on environmental conditions and genotype, varies from 5 to 9 months and is known as a late maturing plant. Therefore, estimating the yield reduction due to leaf fall plays an important role in farm management. In addition to the effects of stressors, some farmers may use sugar beet leaves to raise livestock during the growing season. In this case, too, the leaves are damaged. In the experiment of complete removal of leaves in three sugar beet cultivars, it was observed that complete removal of leaves in Antek and Vico cultivars led to reduced root yield and subsequently white sugar yield was significantly reduced, but In Sharif cultivar, leaf removal had no significant effect on root yield and sugar yield. They also reported that leaf removal increased the percentage of root sugar in Sharif cultivar. Effect of leaf removal time on quantitative and qualitative characteristics of autumn sugar beet cultivars in Gorgan region. Materials and Methods This experiment was carried out in factorial design during the 20192020 crop year in Varsen of Gorgan based on randomized complete block design with three replications. The first factor includes 6 autumn sugar beet cultivars including Monotana, Jerrakws, Rosagold, Chimneh, Veles and Sharif and the second factor includes three levels, pruning in May (leaf development), pruning in June (reducing leaf development) and no pruning (control). Pruning was done using a sickle and the entire aerial part (petiole and leaves) was cut from a height of 5 cm above the crown. Seed bed preparation operations including plowing, retorting, leveling and farrowing were performed before planting. According to the planting plan, they were planted by hand on top of the ridges on November 2019. At the end of the growing season of each harvested plant, root yield and qualitative traits were calculated. The most common method of measuring sugar percentage by polarimetry method was calculated using saccharimeter, sodium and potassium by flame photometry method, harmful nitrogen by aqueous number method and other qualitative characteristics. The analyzed traits were analyzed using SAS software and the means were compared by LSD method at a statistical level of 5%. Results and Discussion Sugar beet cultivars showed significant differences in sugar content (grade), sodium, potassium, extractable sugar content, sugar and molasses extraction coefficient; However, no significant differences were observed between cultivars in terms of harmful nitrogen, alkalinity and root dry matter. Leaf pruning treatments except sodium and molasses were significant in other studied traits. The interaction between cultivars and pruning has also been significant in potassium and molasses traits. Significant differences were observed between the treatments by applying pruning treatment; So that the highest percentage of sugar (14.7%) was observed in the control treatment and the lowest percentage of sugar was observed in the June treatment (12%). The highest root yield was related to Chamineh cultivar with an average of 98 tons per hectare and the lowest root yield was related to Rosagold cultivar with an average of 80 tons per hectare. Due to the decrease in leaf production at the end of the sugar beet growing season, the amount of damage caused by root yield in leaf removal treatment in the final stages of growth (June pruning) is much less than the effect of leaf removal in the middle stage of growth. Conclusions Removal of sugar beet leaves in the final stages of growth had an effect on root quality properties such as sugar content, extractable sugar percentage and sugar extraction coefficient and root yield and reduced the mentioned traits. Root impurities also increased due to defoliation. Most yield losses were obtained when sugar beet leaves were removed or eliminated in the middle stages of growth (May pruning).