1دانشجوی دکتری، گروه مهندسی تولید و ژنتیک گیاهی، دانشگاه شهید چمران اهواز. اهواز، ایران.
2دانشیار، گروه مهندسی تولید و ژنتیک گیاهی، دانشگاه شهید چمران اهواز. اهواز، ایران. (نگارنده مسئول)
3استاد گروه مهندسی تولید و ژنتیک گیاهی، دانشگاه شهید چمران اهواز. اهواز، ایران
4استاد یار گروه مهندسی تولید و ژنتیک گیاهی، دانشگاه علوم کشاورزی ومنابع طبیعی خوزستان ، ایران
5دانشیار، مؤسسه کشاورزی تاسمانی، دانشگاه تاسمانی، تاسمانی، استرالیا.
چکیده
بهمنظور بررسی اثر هورمون سیتوکینین برصفات مورفوفیزیولوژیک و عملکرد دانه ارقام آفتابگردان در دو تاریخ کاشت مختلف، آزمایشی در دانشگاه شهید چمران اهواز در سال زراعی 1401-1400 بهصورت اسپلیت فاکتوریل در قالب طرح بلوکهای کامل تصادفی در سه تکرار انجام شد. دو تاریخ کاشت 15 بهمن و 15 اسفندماه (کاشت بههنگام و دیرهنگام)، به عنوان عاملهای اصلی و محلولپاشی غلظتهای هورمون سیتوکینین (صفر و 50 میکرومولار در لیتر از منبع کینتین) و ارقام آفتابگردان (پروگرس، لاکومکا، شمس، اسکار و قاسم) بهصورت فاکتوریل به عنوان عاملهای فرعی در نظرگرفته شدند. برهمکنش تاریخ کاشت، محلولپاشی هورمون و ارقام آفتابگردان بر بیشتر صفات معنیدار بود، بهطوریکه کاشت دیرهنگام، سبب کاهش تعداد دانه در طبق، وزن هزاردانه، عملکرد دانه، زیست توده، عملکرد و درصد روغن، شاخص کلروفیل، محتوی آب نسبی، شاخص سطح برگ و هدایت روزنهای شد. کاربرد سیتوکینین سبب بهبود صفات مورد مطالعه در هر دو تاریخ کاشت شد. درکاشت دیرهنگام، عملکرد دانه تحت تأثیر هورمون در ارقام لاکومکا، پروگرس، شمس، اسکار و قاسم به ترتیب به میزان 24، 22، 33، 56 و42 درصد افزایش یافت. رقم لاکومکا و پروگرس در هر دو تاریخ کاشت دارای بالاترین عملکرد دانه و روغن بودند. کاربرد سیتوکینین در کاشت به هنگام و دیرهنگام عملکرد دانه (به ترتیب 11 و 24 درصد) و عملکرد روغن (به ترتیب 27 و 34 درصد) رقم لاکومکا را در مقایسه با عدم کاربرد هورمون افزایش داد. لذا به نظر میرسد بهطورکلی محلولپاشی کینتین توانست اثرات منفی تنش گرما را با بهبود صفات مورفوفیزیولوژیکی و بهبود عملکرد دانه و روغن تعدیل بخشد.
Foliar application of cytokinin hormone on morphophysiological and yield traits of sunflower cultivars in late sowing date
نویسندگان [English]
Mahboobeh Khajavi1؛ Afrasyab Rahnama2؛ Moosa Meskarbashi3؛ Seyed amir Moosavi4؛ Matthew Tom Harrison5
1PhD student, Department of Plant Production and Genetics, Shahid Chamran University of Ahvaz.
Ahvaz, Iran
2Associate Professor, Department of Plant Production and Genetics, Shahid Chamran University of
Ahvaz. Ahvaz, Iran (Corresponding author)
3Professor, Department of Plant Production and Genetics, Shahid Chamran University of Ahvaz. Ahvaz,
Iran.
4Assistant Professor, Department of Plant Production and Genetics, Agricultural Sciences and Natural
Resources University of Khuzestan, Iran.
5Associate Professor, Tasmanian Institute of Agriculture, University of Tasmania, Newnham Drive,
Launceston, Tasmania, Australia 7248
چکیده [English]
Introduction Crop yields in tropical regions is threatened by high temperatures during reproductive phase which causes a severe change in physiological and biochemical behavior of the major crops (Salehi et al., 2023). A suitable sowing dates provide adequate growth and development for crops and altered sowing dates is beneficial for crop productivity as it helps the critical growth stages avoid high temperature stress. Manipulating the sowing date is one of the the most important management practices for improving crop yield and resource use efficiency (Srivastava et al., 2018). It has been reported that the highest grain and biological yield of safflower were observed on early sowing date, compared to late sowing dates (Sahu and Thakur., 2016)). Delay in sowing date causes shortening of the growing season and distance of the plant from suitable growing conditions. Cytokinins are effective in response to environmental stresses by triggering a complex signaling network (Verma et al., 2016). To further improve plant growth and production, exogenous cytokinin has been applied to enhance the heat stress tolerance of plants. Exogenous application of cytokinin reduced the inhibitory impact of heat stress on photosynthetic properties, and increased antioxidant system activity (Xu et al., 2010). Hence, the current study aimed to evaluate the effect of cytokinin foliar on morphophysiological traits and quantitative yield of sunflower cultivars in winter planting dates in Ahvaz conditions. Materials & Methods A field experiment carried out in a split plot factorial in randomized complete block design with three replications at the research farm of Shahid Chamran University of Ahvaz in 2022. Main plots consisted of two sowing dates; 3th February and 5th March (Normal and late sowing dates, respectively), and sub plot consisted of factorial arrangement of different concentrations of cytokinin (0 and 50 μm l-1, Kinetin), and sunflower cultivars (Progress, Lakomka, Shams, Oskar and Qasem). The cultivation was performed on 3th February as normal sowing date plants experienced optimum temperature during growth stages. On 5th March as late sowing date, the flowering and grain filling periods were exposed to severe heat stress at the end of growing season Results & Discussion Terminal heat stress in late sowing dates caused a significant decrease in in biological yield, grain yield, grain number per head, 1000-grain weight, oil yield, chlorophyll index, relative water content and stomatal conductance. There was a significant difference among cultivars in terms of all traits. Late sowing date was caused a significant reduction in grain yield of Lakomka, Progress, Shams, Oskar and Qasem cultivars by 32, 30, 32, 37 and 33%, respectively, compared to normal sowing date. It was equal to 1.1, 1.03, 1.1, 1.27 and 1.13% for each day of sowing delay, respectively. The concentration of 50 μm l-1 kinetin improved the studied traits in both sowing dates. In late sowing date, foliar application of cytokinin enhanced grain yield by 24, 29, 14, 25 and 21%, in Lakomka, Progress, Shams, Oskar and Qasem cultivars respectively, when compared to cytokinin-deficient plants. Lakomka and Progress had the highest grain and oil yield in both sowing dates. In optimum and late sowing dates; cytokinin application induced an increase in grain yield (by 11 and 24%, respectively) and oil yield (by 27and 34%, respectively) for Lakomka, when compared to cytokinin-deficient plants. Lakomka cultivar identified as the most tolerant to heat stress due to higher grain and oil yield in both sowing dates and both cytokinin levels compared with other cultivars. Conclusions We focused on foliar application of cytokinin on morphophysiological traits and quantitative yield of sunflower cultivars in response to terminal heat stress to highlight the function of cytokinin in heat stress response and it is potential to increase heat stress tolerance. It appears the delay in optimum sowing date leads to synchronize the plant's reproductive stages with a high temperature at the end of the season. The results of this study provides evidence that exogenous cytokinin (50 μm l-1) can be an effective strategy in improvement of heat tolerance of sunflower under terminal heat stress conditions in tropical regions such as Khuzestan. Acknowledgements: We gratefully acknowledge funding support from Shahid Chamran University of Ahvaz grant number SCU.AA1401.96. Key words: Chlorophyll index, grain yield, oil percentage, stomatal conductance