scholarly journals Cropping systems modify soil biota effects on wheat (Triticum aestivum) growth and competitive ability

Weed Research ◽  
2016 ◽  
Vol 57 (1) ◽  
pp. 6-15 ◽  
Author(s):  
S P Johnson ◽  
Z J Miller ◽  
E A Lehnhoff ◽  
P R Miller ◽  
F D Menalled
2016 ◽  
Vol 67 (7) ◽  
pp. 695 ◽  
Author(s):  
M. C. Zerner ◽  
G. J. Rebetzke ◽  
G. S. Gill

Weed control in broadacre cropping systems is becoming increasingly difficult owing to widespread evolution of herbicide resistance in major weed species. The importance of crop competition in weed management is often overlooked but it can play an important role in cropping systems. Competitive ability of 86 wheat (Triticum aestivum L.) genotypes varying for early vigour was investigated at two sites over two growing seasons against cultivated oats (Avena sativa L.) as a weed mimic. There were significant (P < 0.001) treatment effects of weed, wheat genotype and weed × genotype interaction at the different sites. Mature crop height and early crop vigour were strongly correlated with improved weed suppression and tolerance. Negative correlation between early vigour (normalised difference vegetation index and visual score) and weed-free yield indicates the presence of some yield penalty in high-vigour (HV) lines. Wheat genotypes with high grain yield under weed-free conditions tended to suffer high yield loss from weeds (low tolerance) and allowed greater production of weed seed (low weed suppression). However, many of the HV lines produced significantly higher grain yield than the tested commercial cultivars under weedy conditions. The use of the Finlay–Wilkinson regression approach for assessing cultivar stability revealed a strong association between genotype mean weed suppression and stability across the four environments. Several HV lines showed consistently greater weed suppression than the wheat cultivars investigated. Genotypic variation was much greater for weed suppression than weed tolerance, suggesting greater opportunity for the selection of improved weed suppression in wheat. However, strong positive correlation between weed suppression and tolerance (r = 0.79, P < 0.001) suggests that wheat lines selected on the basis of high weed suppression may also exhibit improved weed tolerance.


2008 ◽  
Vol 88 (5) ◽  
pp. 997-1013 ◽  
Author(s):  
C. J. Willenborg ◽  
R. C. Van Acker

This review summarizes the biological and ecological factors of hexaploid wheat (Triticum aestivum L.) that contribute to trait movement including the ability to volunteer, germination and establishment characteristics, breeding system, pollen movement, and hybridization potential. Although wheat has a short-lived seedbank with a wide range of temperature and moisture requirements for germination and no evidence of secondary dormancy, volunteer wheat populations are increasing in relative abundance and some level of seed persistence in the soil has been observed. Hexaploid wheat is predominantly self-pollinating with cleistogamous flowers and pollen viability under optimal conditions of only 0.5 h, yet observations indicate that pollen-mediated gene flow can and will occur at distances up to 3 km and is highly dependent on prevailing wind patterns. Hybridization with wild relatives such as A. cylindrica Host., Secale cereale L., and Triticum turgidum L. is a serious concern in regions where these species grow in field margins and unmanaged lands, regardless of which genome the transgene is located on. More research is needed to determine the long-term population dynamics of volunteer wheat populations before conclusions can be drawn with regard to their role in trait movement. Seed movement has the potential to create adventitious presence (AP) on a larger scale than pollen, and studies tracing the movement of wheat seed in the grain handling system are needed. Finally, the development of mechanistic models that predict landscape-level trait movement are required to identify transgene escape routes and critical points for gene containment in various cropping systems. Key words: Triticum, coexistence, gene flow, genetically-engineered, herbicide-resistant, trait confinement


2006 ◽  
Vol 86 (2) ◽  
pp. 333-343 ◽  
Author(s):  
H. E. Mason ◽  
D. Spaner

Wheat (Triticum aestivum L.) is the world’s most widely grown crop, cultivated in over 115 nations. Organic agriculture, a production system based on reducing external inputs in order to promote ecosystem health, can be defined as a system that prohibits the use of synthetic fertilizers, chemical pesticides and genetically modified organisms. Organic agriculture is increasing in popularity, with a 60% increase in the global acreage of organically managed land from the year 2000 to 2004. Constraints that may be associated with organic grain production include reduced yields due to soil nutrient deficiencies and competition from weeds. Global wheat breeding efforts over the past 50 yr have concentrated on improving yield and quality parameters; in Canada, disease resistance and grain quality have been major foci. Wheat varieties selected before the advent of chemical fertilizers and pesticides may perform differently in organic, low-input management systems than in conventional, high-input systems. Height, early-season growth, tillering capacity, and leaf area are plant traits that may confer competitive ability in wheat grown in organic systems. Wheat root characteristics may also affect competitive ability, especially in low-input systems, and more research in this area is needed. The identification of a competitive crop ideotype may assist wheat breeders inthe development of competitive wheat varieties. Wheat varieties with superior performance in low-input systems, and/or increased competitive ability against weeds, could assist organic producers in overcoming some of the constraints associated with organic wheat production. Key words: Triticum aestivum L., wheat breeding, low-input agriculture, plant height, early-season growth, tillering capacity, leaf area index


1998 ◽  
Vol 78 (1) ◽  
pp. 171-173 ◽  
Author(s):  
P. Hucl

Increased crop competitiveness may complement existing weed control methods. The objective of this research was to establish whether spring wheat (Triticum aestivum L.) genotypes with contrasting competitive abilities respond differently to weed control levels. Four sibling genotypes differing in competitive ability were grown under simulated weedy conditions and subjected to four weed control levels. The competitive genotypes were superior to the less-competitive genotypes in grain yield under weedy and partially weedy conditions. Key words: Triticum aestivum L., competition, weed control, genotype × weedcontrol interaction


2002 ◽  
Vol 38 (1) ◽  
pp. 1-11 ◽  
Author(s):  
S.S. Dahiya ◽  
Y. S. Chauhan ◽  
C. Johansen ◽  
R. S. Waldia ◽  
H. S. Sekhon ◽  
...  

The performance of newly developed extra-short-duration pigeonpea (Cajanus cajan) genotypes and traditional short-duration pigeonpea cultivars was compared in rotation with wheat in on-farm trials conducted in 1996–97 and 1997–98 in Sonepat (28° N) district in Haryana, and in 1996–97 at Ludhiana (30° N) district in Punjab, India. At both locations, a wheat crop (Triticum aestivum cv. HD 2329) followed pigeonpea. At Sonepat, an indeterminate extra-short-duration genotype ICPL 88039 matured up to three weeks earlier, yet gave 12% higher yield (1.57 t ha−1) and showed less susceptibility to borer damage than did the short-duration cv. Manak. At Ludhiana, extra-short-duration pigeonpea genotypes, ICPL 88039, ICPL 85010 and AL 201 gave similar grain yields to the short-duration T 21 in spite of maturing three to four weeks earlier. Yields of wheat crops following extra-short-duration genotypes were up to 0.75 t ha−1 greater at Sonepat and up to 1.0 t ha−1 greater at Ludhiana. The results of the study provide empirical evidence that extra-short-duration pigeonpea genotypes could contribute to higher productivity of pigeonpea–wheat rotation systems. Most of the farmers who grew on-farm trials in Sonepat preferred extra-short-duration to short-duration pigeonpea types for their early maturity, bold seed size, and the greater yield of the following wheat crop.


Weed Science ◽  
1986 ◽  
Vol 34 (5) ◽  
pp. 730-734 ◽  
Author(s):  
Loren J. Moshier ◽  
Oliver G. Russ ◽  
Joseph P. O'Connor ◽  
Mark M. Claassen

A 3-yr experiment and a 1-yr experiment in continuous winter wheat (Triticum aestivumL. ‘Newton’) and two 3-yr experiments in continuous grain sorghum [Sorghum bicolorL. (Moench.) ‘Co-op SG-10’ or ‘DeKalb DX-42Y’] were conducted to evaluate selected foliage-applied herbicides for control of honeyvine milkweed [Ampelamus albidus(Nutt.) Britt # AMPAL]. Glyphosate [N-(phosphonomethyl)-glycine] applied at 3.4 kg ae/ha, glyphosate plus dicamba (3,6-dichloro-2-methoxybenzoic acid) applied at 1.7 plus 0.6 kg ae/ha, and glyphosate plus 2,4-D [(2,4-dichlorophenoxy)acetic acid] applied at 1.7 plus 1.1 kg ae/ha in summer between harvesting and planting winter wheat and in spring prior to planting grain sorghum effectively reduced honeyvine milkweed regrowth 1 yr after initial application in both cropping systems. One or two additional annual applications did not provide complete control in either cropping system. Applications of 2,4-D at 2.2 kg ae/ha dicamba at 1.1 kg ae/ha and 2,4-D plus dicamba at 1.1 plus 0.6 kg ae/ha were effective if applied consecutively for 3 yr in continuous winter wheat but not in continuous grain sorghum.


2001 ◽  
Vol 52 (12) ◽  
pp. 1235 ◽  
Author(s):  
R. K. Coleman ◽  
G. S. Gill ◽  
G. J. Rebetzke

As weeds develop resistance to a broad range of herbicides, wheat (Triticum aestivum L.) cultivars with superior weed competitive capacity are needed to complement integrated weed management strategies. In this study, agronomic and morphological traits that enable wheat to compete effectively with weeds were identified. Halberd, Cranbrook, and 161 Cranbrook x Halberd doubled haploid (DH) lines were examined in field experiments conducted over two growing seasons. The weed species Lolium rigidum L. (annual ryegrass) was sown in strips perpendicular to the direction of wheat seeding. Various traits were measured during each season with competitive ability determined by both percent loss in wheat grain yield and suppression of ryegrass growth. Width of leaf 2, canopy height, and light interception at early stem elongation (Z31), and tiller number, height at maturity, and days to anthesis were important for competitive ability in 1999. In the previous year, length of leaf 2 and size of the flag leaf contributed to competitiveness. Seasonal effects appeared to have some impact on the relative contribution of crop traits to competitive ability. The morphological traits involved in maintaining grain yield differed from those that contributed to the suppression of ryegrass growth. Development of the Cranbrook x Halberd chromosomal linkage map enabled the putative identification of quantitative trait loci (QTL) associated with competitive ability in the DH population. Many of the QTL were mapped to similar positions in both years. Further, several traits, including time to anthesis, flag leaf size, height at stem elongation, and the size of the first 2 leaves, were mapped to similar positions on chromosomes 2B and 2D. Narrow-sense heritabilities on an entry-mean basis were typically high within each year for traits associated with weed competitive ability. However, large genotype x year interactions reduced these heritabilities, making genetic gain through phenotypic selection difficult. The identification of QTL repeatable over seasons indicates the potential for marker-assisted selection in a wheat breeding program selecting for improved grain yield and weed competitiveness.


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