A genetic analysis of weed competitive ability in spring wheat

2009 ◽  
Vol 89 (4) ◽  
pp. 591-599 ◽  
Author(s):  
T A Reid ◽  
A Navabi ◽  
J C Cahill ◽  
D Salmon ◽  
D Spaner
Keyword(s):  
Grain Yield ◽  
Competitive Ability ◽  
Crop Yields ◽  
Weed Competition ◽  
International Triticeae Mapping Initiative ◽  
Days To Maturity ◽  
Growing Environment ◽  
Selection For ◽  
Free Environment ◽  
Competitive Treatment

Competition with weeds decreases crop yields globally. Breeding for competitive ability against elevated weed pressure can be difficult because the selection for specific traits which contribute to competitive ability may result in yield losses. The widely studied International Triticeae Mapping Initiative (ITMI) population was used to study the genetics of traits associated with competitive ability in a high latitude (52-53ºN) wheat-growing environment in central Alberta, Canada. Grain yield without weed competition and under experimentally sown cultivated oat competition exhibited similar heritability. Grain yield was positively correlated with early season vigour, and negatively correlated with days to maturity in the competitive treatment only. In this study, similar heritability estimates between competition treatments suggest that selection in a weed free environment can lead to improvements in a weedy environment, but some high-yielding lines under competition would be eliminated during selection.Key words: Wheat, weed competition, competitive ability, International Triticeae Mapping Initiative, genetic correlation

Herbicide efficacy for control of annual ryegrass (Lolium rigidum Gaud.) is influenced more by wheat seeding rate than row spacing

2013 ◽  
Vol 64 (7) ◽  
pp. 708 ◽  
Author(s):  
Deirdre Lemerle ◽  
Peter Lockley ◽  
Eric Koetz ◽  
Simon Diffey
Keyword(s):  
Grain Yield ◽  
Weed Control ◽  
Herbicide Resistance ◽  
Water Conservation ◽  
Competitive Ability ◽  
Crop Yields ◽  
Row Spacing ◽  
Lolium Rigidum ◽  
Seeding Rate ◽  
The Impact

Conservation cropping systems with no-till and stubble retention improve soil condition and water conservation. However, tillage is replaced by herbicides for weed control in these systems, increasing the threat of herbicide resistance. In the medium to high rainfall zones of the southern wheatbelt of Australia and under irrigation, wider row spacing is used to enable seeding into heavy stubble loads and to avoid stubble burning. Some evidence suggests that wider rows lead to reduced crop competitive ability and crop yields, greater herbicide dependence, and increased spread of resistance. Our aim was to test the hypothesis that increasing seeding rate compensated for reduced competitive ability at wider row spacings, especially when herbicide performance was suboptimal. We examined the impact of two wheat row spacings (18 and 36 cm) and five seeding rates (resulting in a range of densities of ~80–700 plants/m2) on control of Lolium rigidum with five rates of post-emergence application of diclofop-methyl (Hoegrass®), ranging from label rate to lower rates, over two growing seasons. In the presence of L. rigidum, wheat grain yield was unaffected by row spacing but was significantly reduced at low seeding rates, especially at lower herbicide rates. Lolium rigidum was suppressed at higher crop densities but was also unaffected by row spacing. Grain yield was maximised when post-emergence herbicide was applied at 60–100% of the recommended dose at wheat densities >~300 plants/m2. Significant levels of the weed remained in the crop at anthesis in all treatments. Weed dry matter ranged from 525 g/m2 at low crop densities and with no herbicide to 150 g/m2 with the recommended rate of herbicide and high wheat densities. The implications of manipulating crop competitive ability to improve weed control are discussed, especially in conditions where herbicide performance is unreliable due to weeds developing herbicide resistance or adverse environmental conditions.

Effects of weed competition on flag leaf photosynthesis and grain yield of spring wheat

1999 ◽  
Vol 132 (1) ◽  
pp. 23-30 ◽  
Author(s):  
J. IQBAL ◽  
D. WRIGHT
Keyword(s):  
Grain Yield ◽  
Leaf Area ◽  
Nitrogen Uptake ◽  
Competitive Ability ◽  
Stomatal Density ◽  
Flag Leaf ◽  
Dry Weight ◽  
Weed Competition ◽  
Weed Species ◽  
Weed Density

Three pot experiments were performed at the University of Wales, Bangor, Gwynedd, UK during 1993 to determine if differences in the competitive ability of three annual weeds (Chenopodium album L., Sinapis arvensis L. and Phalaris minor Retz.) were related to their relative effects on leaf growth, gas exchange and nitrogen uptake of spring wheat (cv. Alexandria). In all experiments, wheat density (316 plants m−2) was similar to that in a commercial crop and five weed density treatments (between 0 and 600 plants m−2) were tested. Measurements of gas exchange were made on fully expanded, attached wheat flag leaves on four occasions between emergence and complete senescence in the control and highest weed density treatments. High weed density resulted in a lowering of net photosynthetic rate due to stomatal and non-stomatal factors. Lamina area and stomatal density of wheat flag leaves were decreased, and specific leaf area was increased by weed competition, but the effects on these variables were smaller than on net photosynthesis. Weed density did not affect wheat plant height, but dry weight, grain yield and total N-uptake were decreased with an increase in density of all weed species. The rank order of competitive ability of the species (C. album>P. minor>S. arvensis) was unaffected by weed density and was the same irrespective of whether it was based on the % decreases in wheat grain yield or in total plant dry weight. Averaged over the four measurements made during the grain-filling period there were only small differences between the weed species in their effects on net photosynthetic rate. However, when these were combined with effects on flag leaf area, there were larger differences in calculated net photosynthetic productivity, which were related to differences in the effects of weeds on grain yield. Differences in the competitive ability of weeds were not related to differences in their effects on wheat flag leaf lamina area, specific leaf area, stomatal density or total nitrogen uptake. Differences in competitive ability between weed species were not related to differences in weed plant height, dry weight or nitrogen uptake. It was concluded that the observed effects of weeds on wheat were due either to shading, or to competition for a nutrient other than nitrogen.

scholarly journals Early generation selection strategy for yield and yield components in white oat

2005 ◽  
Vol 62 (4) ◽  
pp. 357-365 ◽  
Author(s):  
Giovani Benin ◽  
Fernando Irajá Félix de Carvalho ◽  
Antônio Costa de Oliveira ◽  
Claudir Lorencetti ◽  
Igor Pires Valério ◽  
...  
Keyword(s):  
Grain Yield ◽  
Indirect Selection ◽  
Grain Weight ◽  
Yield Potential ◽  
High Yield ◽  
Direct Selection ◽  
Selection Strategy ◽  
Breeding Method ◽  
Growing Seasons ◽  
Selection For

Several studies have searched for higher efficiency on plant selection in generations bearing high frequency of heterozygotes. This work aims to compare the response of direct selection for grain yield, indirect selection through average grain weight and combined selection for higher yield potential and average grain weight of oat plants (Avena sativa L.), using the honeycomb breeding method. These strategies were applied in the growing seasons of 2001 and 2002 in F3 and F4 populations, respectively, in the crosses UPF 18 CTC 5, OR 2 <FONT FACE=Symbol>´</FONT> UPF 7 and OR 2 <FONT FACE=Symbol>´</FONT> UPF 18. The ten best genetic combinations obtained for each cross and selection strategy were evaluated in greenhouse yield trials. Selection of plants with higher yield and average grain weight might be performed on early generations with high levels of heterozygosis. The direct selection for grain yield and indirect selection for average grain weight enabled to increase the average of characters under selection. However, genotypes obtained through direct selection presented lower average grain weight and those obtained through the indirect selection presented lower yield potential. Selection strategies must be run simultaneously to combine in only one genotype high yield potential and large grain weight, enabling maximum genetic gain for both characters.

scholarly journals Selection for pollen competitive ability in mixed-mating systems

Evolution ◽  
2018 ◽  
Vol 72 (11) ◽  
pp. 2513-2536 ◽  
Author(s):  
Madeline A. E. Peters ◽  
Arthur E. Weis
Keyword(s):  
Competitive Ability ◽  
Mating Systems ◽  
Mixed Mating ◽  
Selection For
Sign in / Sign up

Export Citation Format

Share Document