نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 دانشآموخته کارشناسی ارشد گیاهان زینتی، دانشکده کشاورزی، دانشگاه شهید چمران اهواز، اهواز، ایران
2 استادیار گروه علوم باغبانی، دانشکده کشاورزی، دانشگاه شهید چمران اهواز، اهواز، ایران.
3 دانشیار گروه علوم زراعت و اصلاح نباتات، دانشکده فناوری کشاورزی ابوریحان، دانشگاه تهران، پاکدشت، تهران، ایران.
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: Given the abundance of sunny days and high light intensity in most regions of Iran, providing shade in urban green spaces is essential. However, a significant challenge for turfgrass, as a fundamental component of urban greenery, is the issue of light deficiency and shading caused by building development as well as tree canopies. A better understanding of the physiological mechanisms of shade tolerance in turfgrasses is necessary for the efficient development of more shade-tolerant cultivars enable of surviving in low-light environments. Based on previous studies, cool-season turfgrasses generally exhibit greater shade tolerance than warm-season species. Tall fescue (Festuca arundinacea Scherb.) is tolerant to heat and drought, and also demonstrates good shade tolerance. Furthermore, no study has yet evaluated the shade tolerance of promising native genotypes and an sample polycross progenies of tall fescue in Iran. Therefore, the objective of this study was to identify superior genotypes in terms of shade tolerance under the climatic conditions of Ahvaz city.
Materials and methods: This research was conducted in an open field at the Horticultural Science Department farm, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz. The experiment was carried out as a factorial arrangement (comprising three shade levels and four tall fescue genotypes) based on a randomized complete block design with four replications. Seeds of three native tall fescues (Festuca arundinacea) genotypes (Aboureihan1, Aboureihan5, and Isfahan2) along with the seeds of a Polycross population were weighed and sown in plastic pots. These pots were 20 cm in height and 10 cm in diameter and contained a mixture of sand, garden soil, and completely composed manure at a 1:1:2 ratios. Following plant establishment and acclimatization to natural conditions, the plants were subjected to experimental shade treatments (60% and 80% shade), and full sunlight from April to June.
Results: The results indicated that shade stress elicited clear morphological and physiological adjustments in tall fescue, characterized by reductions in leaf width, tiller production, biomass accumulation, and the chlorophyll a/b ratio, alongside marked increases in shoot elongation, leaf greenness, ion leakage, relative leaf water content, and the concentrations of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids. Notably, moderate shading (60%) supported optimal performance for root length as well as fresh and dry shoot biomass, suggesting a threshold at which light attenuation becomes beneficial rather than restrictive. Genotypic comparisons further highlighted substantial variability in shade responsiveness. Polycross consistently exhibited superior performance in traits linked to photosynthetic capacity and tissue water status, including greater leaf width, higher relative leaf water content, and elevated chlorophyll a, total chlorophyll, and carotenoid levels. Aboureihan1 excelled in shoot elongation, tillering ability, and canopy color, indicative of a stronger escape-type response under shade. Aboureihan5 demonstrated the greatest root system development and shoot biomass accumulation, reflecting robust carbon allocation and stress resilience. In contrast, Isfahan2 showed higher ion leakage and elevated chlorophyll b, indicating a more stress-sensitive profile with compensatory adjustments in the light-harvesting complex.
Conclusion: Overall, these findings demonstrated Polycross as the most shade-tolerant tall fescue genotype among those evaluated, exhibiting a coordinated physiological strategy that supports superior performance under reduced light environments. This genotype therefore represents a promising candidate for breeding programs targeting enhanced adaptation to shaded or low-light landscapes.
کلیدواژهها [English]
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