Growth and Seed Return of Auxin-Type Herbicide Resistant Wild Mustard (Brassica kaber) in Wheat

The growth and seed return of auxin herbicide resistant (R) wild mustard was compared to that of a susceptible (S) biotype in wheat in the field. In the absence of herbicide, the S biotype accumulated shoot dry matter more quickly than the R biotype throughout most of the growing season. However, in only one of the two years did the S biotype set substantially more seed than the R biotype (3120 versus 2520 seeds plant−1). The recommended dosage of 2,4-D for wild mustard control (420 g ai ha−1) killed all S plants in both years of the study, and severely inhibited growth and seed return of R plants. Shoot dry matter accumulation and seed return of treated R plants were reduced 75 to 90% compared to the untreated control. However, at a density of 20 plants m−2R seed return was still very high; 9000 and 5700 seeds m−2in 1992 and 1993, respectively. The recommended dosage of dicamba (300 g ha−1) did not inhibit the growth and seed return of either S or R wild mustard to the same extent as 2,4-D. Dicamba at 300 g ha−1reduced S shoot dry matter and seed return 80 to 90%, while R shoot dry matter and seed return was reduced 60 to 65%. The results of this study indicate a very high selection pressure for R wild mustard at recommended dosages of 2,4-D. Despite a high selection pressure, and considering the long history of phenoxy herbicide usage on the Prairies, the relatively rare occurrence of phenoxy herbicide resistant weeds implies that the frequency of resistant individuals is very low. From a mathematical model it was determined that the frequency of R wild mustard in an unselected population may be in the order of 10−30.

Download Full-text

Resistance to Aryloxyphenoxypropionate and Cyclohexanedione Herbicides in Wild Oat (Avena fatua)

Weed Science ◽

10.1017/s0043174500076116 ◽

1993 ◽

Vol 41 (2) ◽

pp. 232-238 ◽

Cited By ~ 62

Author(s):

Ian M. Heap ◽

Bruce G. Murray ◽

Heather A. Loeppky ◽

Ian N. Morrison

Keyword(s):

Dry Matter ◽

Cross Resistance ◽

Western Canada ◽

Wild Oat ◽

Recommended Dosage ◽

Susceptible Population ◽

South Central ◽

Repeated Applications ◽

High Level ◽

Very High

Resistance to aryloxyphenoxypropionate and cyclohexanedione herbicides was identified in four wild oat populations from western Canada. Populations UM1, UM2, and UM3 originated from northwestern Manitoba and UM33 from south-central Saskatchewan. Field histories indicated that these populations were exposed to repeated applications of diclofop-methyl and sethoxydim over the previous 10 yr. The populations differed in their levels and patterns of cross-resistance to these and five other acetyl-CoA carboxylase inhibitors (ACCase inhibitors). UM1, UM2, and UM3 were resistant to diclofop-methyl, fenoxaprop-p-ethyl, and sethoxydim. In contrast, UM33 was resistant to the aryloxyphenoxy propionate herbicides but not to sethoxydim. The dose of sethoxydim required to reduce growth of UM1 by 50% was 150 times greater than for a susceptible population (UM5) or UM33 based on shoot dry matter reductions 21 d after treatment. This population differed from UM2 and UM3 that had R/S ratios of less than 10. In the field UM1 also exhibited a very high level of resistance to sethoxydim. In contrast to susceptible plants that were killed at the recommended dosage, shoot dry matter of resistant plants treated at eight times the recommended dosage was reduced by only 27%. In growth chamber experiments none of the four populations was cross-resistant to herbicides from five different chemical families.

Download Full-text

Wild Mustard (Brassica kaber) Resistance to Ethametsulfuron But Not to Other Herbicides

Weed Technology ◽

10.1017/s0890037x00040902 ◽

1996 ◽

Vol 10 (4) ◽

pp. 847-850 ◽

Cited By ~ 11

Author(s):

G. Mark Jeffers ◽

John T. O'Donovan ◽

Linda M. Hall

Keyword(s):

Dry Weight ◽

The Other ◽

Controlled Environment ◽

Susceptible Population ◽

Initial Frequency ◽

Wild Mustard ◽

Resistant Population ◽

Imidazolinone Herbicides ◽

Brassica Kaber ◽

Very High

In 1993, a wild mustard population growing in a canola crop near Wetaskiwin, AB was poorly controlled by ethametsulfuron after only one previous use of the herbicide. Controlled environment experiments were conducted to compare the response of this suspected resistant population (R) with that of a known susceptible population (S) collected near Vegreville, AB to increasing rates of ethametsulfuron, metsulfuron, chlorsulfuron, thifensulfuron, HOE 075032, imazamethabenz, imazethapyr, metribuzin, and 2,4-D. The R wild mustard population was highly resistant to ethametsulfuron, slightly resistant to low rates of metsulfuron but not resistant to any of the other herbicides tested. This suggests that the mechanism of resistance may differ from that reported for other sulfonylurea and imidazolinone herbicides. Since resistance was documented after only 2 yr of ethametsulfuron use, the initial frequency of resistance to this herbicide in wild mustard populations may be very high. Dry weight of untreated plants did not differ significantly between the S and R populations suggesting little or no differences in competitiveness between them.

Download Full-text

Inheritance of picloram and 2,4-D resistance in wild mustard (Brassica kaber)

Weed Science ◽

10.1614/ws-04-149r ◽

2005 ◽

Vol 53 (4) ◽

pp. 417-423 ◽

Cited By ~ 26

Author(s):

Mithila Jugulam ◽

Michael D. McLean ◽

J. Christopher Hall

Keyword(s):

Dominant Gene ◽

Backcross Progeny ◽

Acid Group ◽

Cross Resistance ◽

Herbicide Resistant ◽

Wild Mustard ◽

Herbicide Resistance Gene ◽

Group Resistance ◽

Brassica Kaber ◽

F2 Progeny

The primary goal of this research was to determine the inheritance of cross-resistance to several groups of auxinic herbicides through classical genetic approaches using auxinic herbicide–resistant (R) and –susceptible (S) wild mustard biotypes obtained from western Canada. F1 progeny were raised from crosses between homozygous auxinic herbicide–R and –S wild mustard parental lines. The F1 and F2 populations were assessed for picloram (pyridine group) and 2,4-D (phenoxyalkanoic group) resistance or susceptibility. Analyses of the F1 as well as the F2 progeny indicate that a single dominant gene confers the resistance to picloram and 2,4-D similar to an earlier report of dicamba-based (benzoic acid group) resistance in this wild mustard biotype. Furthermore, analyses of backcross progeny in this species indicate that resistance to all three auxinic herbicides, i.e., picloram, dicamba, and 2,4-D, is determined by closely linked genetic loci. With this information on inheritance of resistance to several auxinic herbicide families, the R biotype of wild mustard offers an excellent system to isolate and characterize the auxinic herbicide–resistance gene.

Download Full-text

Hitting times of local and global optima in genetic algorithms with very high selection pressure

Yugoslav journal of operations research ◽

10.2298/yjor160318016e ◽

2017 ◽

Vol 27 (3) ◽

pp. 323-339 ◽

Cited By ~ 3

Author(s):

Anton Eremeev

Keyword(s):

Genetic Algorithm ◽

Genetic Algorithms ◽

Selection Pressure ◽

Upper Bounds ◽

Hitting Times ◽

Global Optima ◽

High Selection ◽

First Hitting Times ◽

Very High

The paper is devoted to upper bounds on the expected first hitting times of the sets of local or global optima for non-elitist genetic algorithms with very high selection pressure. The results of this paper extend the range of situations where the upper bounds on the expected runtime are known for genetic algorithms and apply, in particular, to the Canonical Genetic Algorithm. The obtained bounds do not require the probability of fitness-decreasing mutation to be bounded by a constant which is less than one.

Download Full-text

Density and row spacing effects on irrigated short wheats at low latitude

The Journal of Agricultural Science ◽

10.1017/s0021859600026691 ◽

1976 ◽

Vol 87 (1) ◽

pp. 137-147 ◽

Cited By ~ 28

Author(s):

R. A. Fischer ◽

I. Aguilar M. ◽

R. Maurer O. ◽

S. Rivas A.

Keyword(s):

Grain Yield ◽

Dry Matter ◽

Light Interception ◽

Dry Matter Production ◽

Seeding Density ◽

High Fertility ◽

Dry Matter Accumulation ◽

Area Index ◽

Matter Production ◽

Very High

SummaryDuring four winter seasons eight spacing and density experiments were made under irrigated high fertility conditions in north-west Mexico (latitude 27° N). Experiments included various Triticum aestivum and T. durum genotypes of spring habit, short stature derived from Norin 10 genes, and contrasting plant type. Measurements included dry-matter production, photosynthetic area index, and light interception during one experiment, total dry matter at maturity in most others and grain yield and its numerical components in all experiments.Grain yield and most other crop characters were unaffected by row spacings within the range 10–45 cm interrow width. The optimal seeding density for maximum grain yield was 40–100 kg/ha (80–200 plants/m2). Yield reductions at lower densities (20, 25 kg/ha) were slight and accompanied by reduced total dry-matter production. Yield reductions at higher densities (160–300 kg/ha) were also slight and were associated with more spikes/m2 but fewer grains/m2 and reduced harvest index. It is suggested that lower than normal preanthesis solar radiation or weather conditions leading to lodging can magnify these yield depressions at higher densities.Measurements showed rapid approach of crops to 95% light interception, reached even at a density of 50 kg/ha within 50 days of seeding. It is suggested that provided this occurs before the beginning of substantial dry-matter accumulation in the growing spikes (60 days after seeding) there will be no loss of grain yield with reduced seeding density. Results point to a ceiling photosynthetic area index for maximum crop growth rate although there was a tendency for rates to fall at very high indices (> 9). This tendency was associated with very high density, high maximum numbers of shoots, poor survival of shoots to give spikes (< 30%) and reduced number of grains/m3;. The relatively low optimal densities seen here may be characteristic of genotypes derived from Norin 10.Genotype × spacing, genotype × density and spacing × density interactions were generally non-significant and always small. There was a tendency for the presence of non-erect leaves or branched spikes to reduce the optimal density, but large differences in tillering capacity had no influence. Differences in lodging susceptibility can however lead to substantial genotype x density interactions.

Download Full-text

Comparison of ABP1 over-expressing Arabidopsis and under-expressing tobacco with an auxinic herbicide-resistant wild mustard (Brassica kaber) biotype

Plant Science ◽

10.1016/j.plantsci.2005.02.010 ◽

2005 ◽

Vol 169 (1) ◽

pp. 21-28 ◽

Cited By ~ 16

Author(s):

J. Mithila ◽

J.C. Hall

Keyword(s):

Herbicide Resistant ◽

Wild Mustard ◽

Brassica Kaber

Download Full-text

Factors influencing the selection of herbicide-resistant biotypes of weeds

Outlook on Agriculture ◽

10.1177/003072707800900605 ◽

1978 ◽

Vol 9 (6) ◽

pp. 283-287 ◽

Cited By ~ 13

Author(s):

J Gressel

Keyword(s):

Selection Pressure ◽

Genetic Resistance ◽

Herbicide Resistant ◽

Factors Influencing ◽

Weed Seeds ◽

Resistance To Herbicides ◽

High Selection ◽

Large Soil ◽

Selection Of

Despite their prolonged use, only a few cases of acquired genetic resistance to herbicides have been reported. This is probably due to a combination of low selection pressure with most herbicides, lower fitness of resistant weeds, the ability of thinned stands of susceptible weeds to produce relatively more seeds, and the large soil reservoir of susceptible weed seeds. Regular use of high selection pressure, highly persistent herbicides could, however, rapidly produce such resistance.

Download Full-text