GDD

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1 - The Effect of Planting Date on Thermal Indices and Dry matter Yield of Different Clover Species
Mohammad Zamanian Mona Poureisa Farid Golzardi

This study aimed to investigate the changes in thermal indices of various clover genotypes under cold stress. A field experiment was conducted to evaluate the effect of different planting dates (14 Sep., 28 Sep., and 8 Oct.) and clover genotypes (late-maturity Persian c چکیده کامل

This study aimed to investigate the changes in thermal indices of various clover genotypes under cold stress. A field experiment was conducted to evaluate the effect of different planting dates (14 Sep., 28 Sep., and 8 Oct.) and clover genotypes (late-maturity Persian clover, mid-maturity Persian clover, early-maturity Persian clover, berseem clover, red clover, and crimson clover). The results showed that delaying the planting date from September 14 to October 8 caused a significant decrease in growing degree-day (GDD), photothermal index (PTI), and heat use efficiency (HUE) in all studied genotypes. Early-maturity Persian clover and crimson clover had the lowest thermal requirements, while red clover had the highest GDD in all the investigated planting dates. During the first cut, the early-maturity Persian clover demonstrated the highest HUE (4.09 kg ha-1 °C days), followed by crimson clover. In contrast, red clover recorded the lowest HUE (1.43 kg ha-1°C days) on the last planting date. Early-maturity Persian clover and crimson clover may be preferred for forage production under cold stress due to their higher HUE values. The highest dry matter yield of the first cut (6300 kg ha-1) was obtained on the first planting date and by mid-maturity Persian clover, while the lowest yield (2429 kg ha-1) was obtained on the last planting date and by red clover. Overall, delayed planting dates resulted in accelerated development and decreased thermal requirements in clover species. The early-maturity genotypes were found to be more suitable for forage production under environmental stresses such as water shortages. پرونده مقاله

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2 - Impact of Sowing Date on Growth, Phenology and Yield of Three Ecotypes of Astragalus cyclophyllon G. Beek in Semirom Rangelands, Iran
Masoud Esmaeili Sharif Amir Hooshang Jalali Roja shabahang

10.30495/rs.2023.686392

In order to compare the effect of sowing date on plant growth, development stages and forage yield of three Astragalus cyclophyllon G. Beek ecotypes, a study was conducted in 2010-2011 cropping years in Hanna station, Semirom county, Iran. Three Astragalus ecotypes were چکیده کامل

In order to compare the effect of sowing date on plant growth, development stages and forage yield of three Astragalus cyclophyllon G. Beek ecotypes, a study was conducted in 2010-2011 cropping years in Hanna station, Semirom county, Iran. Three Astragalus ecotypes were originated from Hanna, Golpayegan and Chadegan in Isfahan province, Iran. Seeds were sown in spring and autumn sowing dates using split plot design based on completely randomized blocks in three replications. The results showed that the effect of year was not significant, but the ecotype by sowing date interaction effect was significant on yield and yield components (P<0.01). The required temperature units such as Growth Degree Days (GDD) for spring and autumn sowing dates were 2848°C and 2793°C, respectively. The effect of sowing date on emergence percent and forage yield was significant (p<0.05). Regardless of the ecotype type, the percentage of seed germination and forage yield in autumn sowing were 51 and 60% higher than spring sowing date, respectively. The dry weight of Hanna ecotype in autumn cultivation was 1280 kg ha-1, which was 55.8% and 58% higher than Golpayegan and Chadegan ecotypes, respectively. The reason for the increased yield in Hanna ecotype was of a higher ratio of its leaves. It was concluded that cultivation of Hanna ecotypes due to its higher forage production was recommended for cultivation in dryland farming and also to prevent its extinction in the study region. پرونده مقاله

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3 - Required Growing Degree-Days (GDDs) for each Phenological Stage of Fritillaria imperialis
Elahe Zafarian Ataollah Ebrahimi Ali Abbasi Esmaeel Asadi

Studying plant phenology is very important to regulate the rangeland utilization. Plant phenology can be determined by Growing Degree Days (GDDs). Since temperature varies yearly, the phenological stages may consequently differ yearly. Determining the base temperature i چکیده کامل

Studying plant phenology is very important to regulate the rangeland utilization. Plant phenology can be determined by Growing Degree Days (GDDs). Since temperature varies yearly, the phenological stages may consequently differ yearly. Determining the base temperature is one of the key steps in the calculation of GDDs. The aim of this study was to calculate the required GDDs for each phenological stage to predict phenological stage of Fritillaria imperialis based on GDDs in the consequent years. To do so, Fritillaria bulbs were placed at constant temperatures of 0, 1, 2, 3 and 4°C. The length of sprouts as a growth index was measured as a function of temperature. Plant chronology was recorded in three day intervals from March 1st, 2016 in the field and the date of each phenological stage was recorded in the form of an index developed by combining Fick and Haun indices. Then, 20 plant individuals were selected in Dasht-e-Laleh of Kouhrang County, Iran and their growth stages were recorded. Meanwhile, the required amount of accumulated GDDs (AGDDs) to reach each phenological stage was also calculated. Results showed that Fritillaria imperialis began the sprouting (phase E) after receiving 130.75 GDDs on March 23rd, 2016. The emergence of leaves began on 27th March with 166.30 GDDs and finished on 9th April. Finally, this plant on 9th May received 560 AGDDs and went to senescence. Based on the phenological data, when the plant received 240 AGDDs, flowering stage started. The most appropriate time for tourist entrance is in the R2 stage (flower opening) when the plant receives 298.8 AGDDs and the best exit time is when the plant receives 359.2 AGDDs. So, the relationship between phenological stages of the plant and GDDs will be useful in visiting the site in terms of ecotourism and determining proper visit times. پرونده مقاله

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4 - Studying the Impacts of Cold Temperature on Morphological and Phonological Development of Poa pratensis and Poa trivialis Regarding GDD
Ebrahim Baghdadi Ali Ashraf Jafari Mohammad Ali Alizadeh Amir Hossain Gorji

Poa genus has a high value for grazing and forage conservation concerning thelivestock. In order to study the impacts of cold temperature and Growing Degree Days(GDD) on seedling morphological trait and phonological development of two speciesinvolving Poa pratensis and چکیده کامل

Poa genus has a high value for grazing and forage conservation concerning thelivestock. In order to study the impacts of cold temperature and Growing Degree Days(GDD) on seedling morphological trait and phonological development of two speciesinvolving Poa pratensis and Poa trivialis, this research was conducted in laboratory andgreenhouse and outdoor of Research Institute of Forest and Rangeland in Tehran, Iran. Theseed samples were moist chilled at 4 °C for two weeks as compared to the control treatment.Samples of both treatments (chilling and control) were transferred into a germinator at20±4°C for 15 days. All the pots were placed in a normal glasshouse at 20±10°C for onemonth. The 30th day age pots have been transferred into the cold rooms at 4°C for two weeks incomparison with control treatment. The seedling vegetative traits were measured same as thelaboratory. For outdoor experiment, half of pots of greenhouse were transferred outdooruntil their flowering and growth stages and GDD were recorded. In the flowering stage,morphological characteristics including stem number, stem length, peduncle length,panicle length, plants‟ fresh and dry weight of each ecotype were recorded. The collecteddata of each experiment were separately analyzed using factorial experiment based oncompletely randomized design. The results of laboratory experiment showed thesignificant effects of chilling (4 °C) treatment on germination percent, speed of germinationin both species and vigor index for P. pratensis. Regarding P. pratensis in vegetative stage,the mean values of all of traits were higher in control treatment than those of coldtreatment. Similarly, in outdoor experiment, the mean values of reproductive traits in thecontrol treatment were higher than those for cold treatment concerning both species. P.pratensis had higher mean values for all of reproductive traits as compared to P. trivialis.Results also showed that GDD of plants which were subjected to cold treatment werelower than those for control treatment for both vegetative and flowering stages. It has beenconcluded that cold treatment reduced flowering dates in reproductive stage. پرونده مقاله

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5 - بررسی تاثیر تغییر اقلیم بر طول دوره رشد و مراحل فنولوژیک رشد گندم در منطقه زابل
حمید محمدی محمود رمرودی محمد بنایان محمد رضا اصغری پور حمیدرضا فنایی

تغییر اقلیم می‌تواند با تغییر در طول دوره رشد و عملکرد محصولات کشاورزی، همچنین میزان تبخیر و تعرق گیاهان و تقاضای آب در کشاورزی را تحت تأثیر قرار دهد. در این مطالعه تعدادی از مدل‌های گردش عمومی انتخاب و پیش بینی میانگین دمای سالانه زابل مورد آزمون صحت سنجی قرار گرفت. ار چکیده کامل

تغییر اقلیم می‌تواند با تغییر در طول دوره رشد و عملکرد محصولات کشاورزی، همچنین میزان تبخیر و تعرق گیاهان و تقاضای آب در کشاورزی را تحت تأثیر قرار دهد. در این مطالعه تعدادی از مدل‌های گردش عمومی انتخاب و پیش بینی میانگین دمای سالانه زابل مورد آزمون صحت سنجی قرار گرفت. ارزیابی نتایج مدل‌های اقلیمی، تا اواخر قرن حاضر افزایش میانگین دمای 2 تا 5 درجه سانتی گراد در زابل را پیش بینی می‌کنند. به همین منظور سه سناریوی دمایی (صفر، 2+ و 5+) به ترتیب به عنوان سناریو عدم تغییر دما، حداقل افزایش و حداکثر افزایش تعریف شده و به داده دمایی روزانه دیده بانی شده اضافه شد. تاثیر تغییر اقلیم بر طول دوره رشد و مراحل فنولوژیک گندم (Triticum aestivum) و همچنین تبخیر وتعرق در منطقه زابل براساس تاریخ و میانگین رقم‌های مورد کشت رایج مورد بررسی قرار گرفتند. برای محاسبه مراحل فنولوزیک از روش GDD استفاده شد. برای اندازه‌گیری اثر سناریوهای تغییر اقلیم بر تبخیر وتعرق مدل هارگریوز -سامانی استفاده شد. نتایج نشان داد نسبت به سناریوی عدم افزایش در اثر افزایش 2 درجه سانتی گراد میانگین دمای روزانه تا اواخر قرن طول دوره رشد گندم 14 روز کاهش می‌یابد. همچنین تبخیر و تعرق در مرحله آغازین رشد 20 درصد افزایش خواهد یافت. افزایش 5 درجه سانتی گراد دما باعث کاهش 32 روزه طول دوره رشد گندم و افزایش 46 درصدی تبخیر و تعرق در مرحله آغازین رشد گندم در منطقه خواهد شد. تغییر اقلیم نظام تولید گندم را در منطقه تحت تاثیر قرار خواهد داد. پرونده مقاله

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6 - Effects of Vermicompost and Chemical Fertilizers on Phonological and Phytochemical Traits of Soybean (Glycine max L.)
FARIBA MOHAMMADALIZADE MEHRDAD ATAIE KACHOIE SEYED MOJTABA HASHEMI JAZI

Abstract One of the basic principles of sustainable agriculture is the use of organic fertilizers in agricultural ecosystems with the purpose of eliminating or substantially reducing the use of chemical inputs. To evaluate the effect of different amounts of vermicompos چکیده کامل

Abstract One of the basic principles of sustainable agriculture is the use of organic fertilizers in agricultural ecosystems with the purpose of eliminating or substantially reducing the use of chemical inputs. To evaluate the effect of different amounts of vermicompost on some phonological and phytochemical traits of soybean, an experiment was conducted at Agriculture and Natural Resources Research Center of Shahrekord in 2013. The experiment was conducted in a randomized complete block design including vermicompost treatments (10, 20, 30, 40 and 50 ton.ha-1), chemical fertilizer based on soil testing analysis in the amount of 300 (kg.ha-1) (N.P.K: 20.20.20), and control (no fertilizer). The results showed that 40 ton.ha-1 vermicompost had a positive and significant effect on the soybean phonological stages, the content of chlorophyll a and b and carotenoid. Significant reduction of the required GDD from planting to germination, flowering, and pod stage, but required GDD was observed from increased the pod stage to full maturity was significantly increased. In addition, the chlorophylls a and b content and carotenoid were increased in comparison with control treatment. It appears that due to the positive effects of organic fertilizers on soil physical and chemical properties and gradual releasing of the soil’s required elements along with the high capacity of the humidity perseverance, they can be appropriate alternatives for chemical fertilizers. Keywords: Soybean, Vermicompost, Photochemistry, Phonological, GDD, Chlorophyll a and b, Carotenoid پرونده مقاله

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