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221.
Karel Klem Petra Rajsnerová Kateřina Novotná Otmar Urban Michal V. Marek 《Weed Biology and Management》2014,14(4):262-270
The impact of the relative time of emergence on the growth allometry of Galium aparine L. (cleavers) in competition with Triticum aestivum L. (spring wheat) was studied in a greenhouse experiment. The hypothesis that changes in growth allometry, particularly in the leaf area/height ratio, caused by a shift in the relative time of emergence, could lead to plants overcoming the competition or to competitive suppression was tested. The plant height, dry weight, total leaf area and vertical distribution were analyzed during the first 83 days of growth. The late emergence of G. aparine substantially influenced the growth dynamics for the dry weight and total leaf area. The dynamics of height growth were affected only following a significant delay in G. aparine emergence. The ratio of dry weight to total leaf area was almost unaffected by the competition. By contrast, the allometric relationship between the plant height and total leaf area was highly sensitive to the relative time of emergence. The results suggest that height is the most important growth trait for the plants to resist increasing competition. Even though the plants responded to competition with elongation, the physiological costs linked with “shade avoidance” caused reductions in the dry weight and leaf area growth that resulted in the total suppression of the late‐emerging individuals, in particular when their emergence was >10 days after that of the crop. 相似文献
222.
Anna Kozłowska-Makulska Jerzy Syller Marek S. Szyndel Olivier Lemaire Salah Bouzoubaa Etienne Herrbach 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(2):337-341
Different field isolates of the ‘beet poleroviruses’ Beet mild yellowing virus (BMYV) and Beet chlorosis virus (BChV) (genus Polerovirus, family Luteoviridae) collected in France and Poland were evaluated for transmissibility from and to sugar beet plants by different aphid species.
In general, both BMYV and BChV were efficiently transmitted by Myzus persicae and by a French clone of Macrosiphum euphorbiae. In contrast, transmissibility of the two poleroviruses by an English clone of M. euphorbiae was evidently weaker, although the aphid samples contained the virus as demonstrated by RT-PCR. None of the BMYV or BChV
isolates was transmitted by Aphis fabae or Myzus ascalonicus. In attempting to correlate biological properties with molecular variations, the RT proteins were sequenced. Some amino acid
point variations, presumably affecting aphid transmissibility, were identified. 相似文献
223.
224.
Jin Zhao Qingwu Xue Kirk E. Jessup Thomas H. Marek Wenwei Xu Jourdan Bell 《Journal of Agronomy and Crop Science》2023,209(1):116-131
Deficit irrigation (DI) is an effective way to save irrigation water while maintaining sustainable yield in irrigated crops. However, limited information is available related to canopy structure and solar radiation use under DI condition. In this study, our objective was to assess maize hybrids for leaf development, photosynthetically active radiation (PAR) interception and water use under DI condition. Field experiments were conducted in 2016 and 2017 in four maize hybrids at well-watered (I100, referring to 100% evapotranspiration [ET] requirement) and DI (I75, referring to 75% ET requirement) water regimes. Compared to I100, I75 did not reduce maize biomass and grain yield. Although DI reduced the leaf appearance rates (1.5% in 2016 and 7.6% in 2017) and resulted in greater variations in leaf area index (LAI) among hybrids, the amount of PAR interception was not affected during the growing season. DI significantly reduced the seasonal ET in both years (19.8% in 2016 and 26.6% in 2017). All the hybrids extracted more soil water (29 mm in 2016 and 27 mm in 2017) at I75 than at I100. Maize plants at I75 had greater water use efficiency (WUE) (1.68 kg m−3) than those at I100 (1.41 kg m−3). However, DI did not affect radiation use efficiency (RUE). In conclusion, DI at I75 maintained grain yield through improved soil water extraction and WUE but stable canopy radiation interception and RUE. 相似文献