بررسي پاسخ هاي رشدي بخش هوايي و زيرزميني گل ليزيانتوس تحت افزايش گاز گلخانه اي دي اكسيد كربن در كشت هيدروپونيك

Growth Response of Aboveground and Belowground of Eustoma grandiflorum to Elevated Co2 in Hydroponic Culture

افزایش دی¬اكسید¬كربن اتمسفر به عنوان یكی از مشخصه¬های تغییر اقلیم به میزان زیادی بر بهره¬دهی جهانی، بخش كشاورزی اثر می-گذارد. بنابراین هدف از انجام این پژوهش بررسی اثرات افزایش گاز گلخانه¬ای دی¬اكسید¬كربن بر پاسخ رشدی اندام¬های هوایی و زیرزمینی دو رقم گل لیزیانتوس در شرایط كشت هیدروپونیك است. این تحقیق در گلخانه تحقیقاتی دانشكده كشاورزی، دانشگاه فردوسی مشهد، در قالب آزمایش كرت¬های خرد شده بر پایه طرح كاملاً تصادفی با سه تكرار انجام شد. تیمارها شامل سه غلظت دی¬اكسید¬كربن ۳۸۰ به عنوان شاهد، ۷5۰ و ۱۰۵۰ پی¬پی¬ام و دو رقم گل شاخه بریده لیزیانتوس Yolde White و GCREC-Blu بود. با توجه به نتایج می¬توان این¬گونه بیان داشت كه اثر تیمار دی¬اكسید¬كربن بر ارتفاع، طول میانگره، وزن خشك ساقه و ریشه، سطح و حجم ریشه و نسبت ریشه به ساقه در سطح احتمال 1 درصد معنی¬دار شد و در بین دو رقم تنها از نظر وزن خشك ساقه، تفاوت معنی¬داری در سطح احتمال 5 درصد مشاهده شد. اثر متقابل دی¬اكسید¬كربن و رقم بر روی هیچ یك از صفات مورد مطالعه تأثیر معنی¬داری نداشت. در یك نگاه كلی، افزایش دی¬اكسید¬كربن موجب افزایش تمامی پارامترهای رشدی بخش هوایی و زیرزمینی گیاه لیزیانتوس شد و بیشترین و كمترین تأثیر در تمامی صفات به ترتیب مربوط به غلظت 1050 پی¬پی¬ام و شاهد بود. در نتیجه تغییرات گاز دی¬اكسید¬كربن در اتمسفر می¬تواند تأثیرات بسیار چشمگیری بر روی گیاه بگذارد كه بدین ترتیب می¬توان برخی اثرات تغییر اقلیم در آینده را بر روی كیفیت تولید تجاری گل¬های شاخه بریده پیش¬بینی و بررسی نمود.

Introduction: One of the climate change sign is variation in greenhouse gases in the Earth ʹs atmosphere. Carbon dioxide is the most important greenhouse gas that is released into the atmosphere by humans. It is expected that addition of carbon dioxide could effect the energy balance and global climate. Climate change is effective on agricultural productions. It is clear that different plants have different responses to Co2 variation. These responses are consisting of yield, growth characteristic and variation in root/shoot ratio of plants. On the other hand, using growing media are expanding for plants because of their advantages such as plants nutrient control, reducing the incidence of diseases and pests and increasing the quantity and quality rather than soil cultivation. Properties of various materials as substrates influence directly or indirectly on plant growth and crop production., Hydroponic method can be considered as one of the important methods to optimize water use in agriculture, especially in many countries are located in arid and semi-arid regions that have water crisis. Lisianthus is one of the most beautiful flowers with folded petals in white, blue and purple. I-ts scientific name is Eustoma grandiflorum from the family of Gentianaceae and native to North America. It has variety of annual, biennial or short-lived perennial. The aim of this study was to explore the effect of Co2 enrichment on growth response of aboveground and belowground of Eustoma grandiflorum under increasing of Co2 greenhouse gases in hydroponic culture. Materials and Methods: The experiment was done as a split-plot based on completely randomized experimental design with three replications at greenhouse of Ferdowsi University of Mashhad. The treatments were consists of three concentrations of carbon dioxide (380 as controls, 750 and 1050 ppm) as main plots and two cultivars Yodel white and GCREC-blue as subplots. Some characteristic such as plant height, internode length, root volume, root area, root and shoot dry weight were measured. Data were analyzed by JMP software Version 8 using analysis of variance (ANOVA) and significant differences between means were determined by using LSD test at P < 0.05. Results and Discussion: The results of analysis of variance indicated that the effect of Co2 treatment was significant (p <0.01) for all measured traits except shoot diameter. The effect of cultivars was significant only on shoot dry weight (P <0.05). In other words between two cultivars, Eustoma grandiflorum was significantly different only in shoot dry weight. The interaction effect of carbon dioxide and cultivars was not significant on studied traits. According to our results with increasing of carbon dioxide the amount of plant height, internodes length, shoot dry weight, root area, root volume, root dry weight and root/ shoot ratio were increased. The highest and lowest of each traits was observed in 1050 ppm of carbon dioxide and control (380 ppm), respectively. The effect of cultivars on shoot dry weight was significant and Yolde white has more shoot dry weight than Gcrec Blue variety. Other studies showed that increasing of carbon dioxide concentration in Sesamum indicum increased plant height, number of nodes and node length. Kamali et al. (2004) reported that carbon dioxide on Gomphrena globosa had significant effect on plant height and shoot diameter Increasing of Co2 could increase carbon fixation in C3 plants and transition of carbon to roots lead to increased root biomass. It seems that the root elongation and increasing penetration of plant roots into the soil is due to absorb nutrients to supply shoot growth. Thus, carbon dioxide concentration increased development of plant roots in the soil. Conclusions: Increasing of carbon dioxide could improve growth of aboveground and belowground of Eustoma grandiflorum. Application of 1050 ppm carbon dioxide had most effect on all traits. So, variation of carbon dioxide in the atmosphere could have significant effects on the plants. From these results, it can be predicted some future effects of climate change on the quality of commercial production in cut flowers.