نوع مقاله : مقاله پژوهشی
نویسندگان
1 استادیار، بخش تحقیقات علوم زراعی و باغی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان فارس، سازمان تحقیقات، آموزش و ترویج کشاورزی، شیراز، ایران.
2 استادیار، بخش تحقیقات اصلاح و تهیه بذر چغندرقند، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان فارس، سازمان تحقیقات، آموزش و ترویج کشاورزی ، شیراز، ایران.
3 دانشیار، بخش تحقیقات علوم زراعی و باغی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان فارس، سازمان تحقیقات، آموزش و ترویج کشاورزی، شیراز، ایران.
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
To study the temporal variation in agronomic traits, grain yield, yield components, and radiation use efficiency of sixteen commercial bread wheat cultivars released from 1979 to 2022, a field experiment was carried-out using randomized complete block design with three replications at Zarqhan agricultural research station, Fars province, Iran, in 2022-23-2023-24 cropping seasons. Days to physiological maturity, plant height, grain yield and its components were measured. Radiation use efficiency for four phenological stages and grain yield was also measured. The results showed that the temporal variation of grain yield of bread wheat cultivars released from 1979 to 2022 was increasing, which was mainly due to increase in 1000-grain weight and harvest index. Plant height and days to physiological maturity of newer cultivars decreased. The results implied that increasing temporal variation in grain yield mainly was due to increases in 1000-grain weight, shorter plant height, and to improvement in radiation use efficiency at the flowering stage in newer bread wheat cultivars.
Keywords: Bread wheat, day to flowering, day to physiological maturing, yield 1000 grain weight, harvest index.
Introduction
Since the 1960s, global wheat yield improvement has resulted from both genetic progress and agronomic management. Breeding has significantly increased grain yield, especially after the Green Revolution. In Iran, genetic gain in wheat grain yield has been reported as 83 kg ha⁻¹ yr⁻¹ and 40 kg ha⁻¹ yr⁻¹ (Esmaeilzadeh Moghaddam et al., 2014). Key factors driving this progress include increased 1000-grain weight (TGW), reduced plant height, earlier maturity, improved harvest index (HI).
Further increase in grain yield, however, requires enhanced biomass production, which depends on radiation use efficiency (RUE). Some studies found that breeding improved RUE at flowering, while others reported no significant difference between old and new cultivars (Aisawis et al., 2015). Given the lack of information on RUE temporal variations at different phenological stages of Iranian bred wheat cultivar relaesed from 1979 to 2022, this study aimed to investigate temportal variation in grain yield, yield components, and RUE in 16 bread wheat cultivars released over four decades.
Materials and Methods
A field experiment was carried-out to study the temporal variations in grain yield, yield components, and radiation use effieciency of 16 bread wheat cultivars released from 1979 to 2022 in Iran. The experiment was carried-out using randomized complete block design with there replications in 2022-23 and 2023-24 cropping seasons at Zarghan agricultural research station, Fars province, Iran. Sixteen commercial bread wheat cultivars included: Azadi, Ghods, Falat, Niknejad, Mahdavi, Marvdasht, Shiraz, Parsi, Sirvan, Talaei, Torabi, Amin, Jalal, Danesh, Sepehr, and Bamdad.
Each plot consisted of four rows of 10 meter length and 20 centimeter row spacing with seeding rate of 400 seed m⁻². Dry matter weight and absorbed photosynthetically active radiation (PAR) at four growth stages: stem elongation, heading, flowering, and grain filling were measured. PAR interception was recorded using a linear PAR/LAI ceptometer (AccuPAR LP-80). RUE (g MJ⁻¹) was calculated as the ratio of accumulated dry matter to accumulated intercepted PAR. Agronomic traits including days to physiological maturity, plant height, spikes m⁻², grains spike-1, TGW, HI, and grain yield were measured. Combined analysis of variance was performed using SAS software, and means were compared using Tukey's test.
Results and Discussion
Combined analysis of variance revealed significant (p < 0.01) differences between bread whaet cultivars for all agronomic traits and grain yield, indicating considerable genetic variation. Grain yield showed highly significant (R² = 0.50**) increasing temporal variation in bread wheat cutivars released from 1979 to 2022, mainly due to increased TGW (R² = 0.78**) and, to some extent, improved HI. Plant height and days to physiological maturity decreased in newer cultivars, implying the success story of breeding programs in developing semi-dwarf and early‑maturing bread wheat cultivars.
Although grains spike-1 showed a decreasing temporal variation, this reduction was compensated by increased grain weight. RUE at the flowering stage and RUE for grain yield significantly increased during the period of 1979 to 2022. High‑yielding cultivars (e.g., Amin, Bamdad, Parsi, Sirvan) generally showed greater RUE at the flowering stage.
Correlation analysis revealed that grain yield was positively correlated with spikes m⁻² (r = 0.619*), TGW (r = 0.679**), and HI (r = 0.562**), but negatively correlated with plant height (r = -0.537*) and grains spike-1 (r = -0.641*). These findings are in agreement with the results reported by other researchers (Aisawi et al., 2015; Esmaeilzadeh Moghaddam et al., 2014). The results demonstrated that increased grain weight and reduced plant height have been the main characteristics contributed to enhancement of grain yield.
The lack of significant differences in RUE at early growth stages agrees with Acreche et al. (2009), however, the improved RUE at the flowering stage in newer cultivars supported the positive impact of breeding on this trait during the reproductive stage (Reynolds et al., 2017). Consequently, future breeding programs should focus and prioritize selection for increased 1000-grain weight and reduced plant height as well as incorporating radiation use efficiency at the flowering as a complementary trait to further enhance genetic gain in grain yield. These findings provide invaluable insights for future breeding programs aimed at developing high yielding bread wheat genotypes adapted to temperate agro-climatic zone of Iran.
References
Acreche, M.M., Briceño-Félix, G., Martı´n Sa´nchez, J.A. and Slafer, G.A. 2009. Radiation interception and use efficiency as affected by breeding in Mediterranean wheat. Field Crops Research, 110, pp.91-97. DOI: 10.1016/j.fcr.2008.07.005
Aisawi, K.A.B., Reynolds, M.P., Singh, R.P. and Foulkes, M.J. 2015. The physiological basis of the genetic progress in yield potential of CIMMYT spring wheat cultivars from 1966 to 2009. Crop Science, 55, pp. 1749-1764. DOI: 10.2135/cropsci2014.09.0601
Esmaeilzadeh Moghaddam, M., Jalal Kamali, M.R., Anet, Z., Roshani, M. and Ghodsi, M. 2014. Temporal variation in phenological characteristics, grain yield, and yield components of spring bread wheat (Triticum aestivum L.) cultivars released in Iran between 1952 and 2009. Crop Breeding Journal 4(1), pp. 57-64. DOI: 10.22092.cbj.2014.109673
Reynolds, M.P., Pask, A.J.D., Hoppitt, W.J.E., Sonder, K., Sukumaran, S., Molero, G., […] and Joshi, A.K. 2017. Strategic crossing of biomass and harvest index source and sink achieves genetic gains in wheat. Euphytica, 213(11), e257. DOI: 10.1007/s10681-017-2040-z
کلیدواژهها [English]
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