Effects of Photoperiod on Reproductive Development in Velvetleaf (Abutilon theophrasti)

Weed Science ◽  
1995 ◽  
Vol 43 (4) ◽  
pp. 627-633 ◽  
Author(s):  
David T. Patterson
Keyword(s):  
Weed Management ◽  
Vegetative Growth ◽  
Competitive Ability ◽  
Simulation Models ◽  
Reproductive Development ◽  
Fruit Weight ◽  
Weed Growth ◽  
Growth Differences ◽  
Shoot Weight ◽  
Reciprocal Transfer

When velvetleaf plants from Mississippi and Minnesota populations were maintained in growth chambers with day/night temperatures of 29/23 C and photoperiods of 11, 12, 13, 14, and 15 h, flower buds and open flowers appeared first in the 12 h photoperiod. Buds and flowers appeared 2 to 4 d later at photoperiods of 11, 13, or 14 h. Increasing the photoperiod beyond 14 h to 15 h delayed bud appearance an additional 7 d in the MN plants and 12 d in the MS plants. Open flowers appeared four to five nodes higher, 10 d later at 15 than at 14 h in the MN plants and 20 d later in the MS plants. Vegetative shoot weight and fruit weight 73 d after emergence were greater in 13 h or longer photoperiods than at 11 or 12 h. In shorter photoperiods, MN plants produced more vegetative growth than MS plants, but the reverse occurred at longer photoperiods where MS plants were taller than MN plants. These growth differences occurred because earlier shifts in allocation to reproductive growth in MN plants limited their vegetative growth, particularly in the longest photoperiods. Differences in rate of reproductive development between populations were not evident until photoperiod exceeded 13 h. Reciprocal transfer of plants of the MS population between short and long photoperiods revealed the durations of the juvenile (pre-inductive), inductive, and post-inductive phases to be 3 to 5, 7 to 8 (short day) or 30 (long day), and 10 to 11 d, respectively. Differences in competitive ability among latitudinal biotypes of photoperiodically-sensitive weeds may depend on time of emergence in the field and consequent photoperiod exposure. Weed growth simulation models to be used in development of expert systems for weed management should take photoperiodic sensitivity into account.

Competitive ability of Australian canola (Brassica napus) genotypes for weed management

2014 ◽  
Vol 65 (12) ◽  
pp. 1300 ◽  
Author(s):  
Deirdre Lemerle ◽  
David J. Luckett ◽  
Peter Lockley ◽  
Eric Koetz ◽  
Hanwen Wu
Keyword(s):  
Brassica Napus ◽  
Grain Yield ◽  
Weed Management ◽  
Competitive Ability ◽  
Cropping Systems ◽  
Low Cost ◽  
Integrated Weed Management ◽  
Brassica Napus L ◽  
Herbicide Resistant ◽  
Weed Growth

Canola (Brassica napus L.) is an important break crop in Australian cropping systems but weeds are a major cost to production and herbicide-resistant weeds are spreading. The potential competitive ability of canola genotypes to both suppress weed growth and maintain grain yield and quality in the presence of weeds has not been determined in Australia. Two experiments examined the range in competitive ability of 16 B. napus genotypes against annual ryegrass (Lolium rigidum Gaud.) and volunteer wheat (Triticum aestivum L.) over two contrasting seasons. Weed biomass at flowering was generally reduced 50% more in the presence of the strongly competitive genotypes than the least competitive, and this has significant benefits for lower weed seed production and reduced seedbank replenishment. Suppression of weed growth was negatively correlated with crop biomass. Significant differences in grain yield of canola were recorded between weedy and weed-free plots, depending on crop genotype, presence of weeds and season. Crop yield tolerance (where 0% = no tolerance and 100% = complete tolerance) to ryegrass competition ranged from 0% (e.g. with CB-Argyle) to 30–40% (e.g. with the hybrids 46Y78 and Hyola-50) in the dry season of 2009. Yield tolerance was higher (50–100%) with the lower densities of volunteer wheat and in the 2010 season. The range between genotypes was similar for both conditions. The hybrids and AV-Garnet were higher yielding and more competitive than the triazine-tolerant cultivars. The ranking of genotypes for competitiveness was strongly influenced by seasonal conditions; some genotypes were consistently more competitive than others. Competitive crops are a low-cost tactic for integrated weed management to reduce dependence on herbicides and retard the spread of herbicide-resistant weeds.

Volunteer potato interference in carrot

Weed Science ◽  
2006 ◽  
Vol 54 (1) ◽  
pp. 94-99 ◽  
Author(s):  
Martin M. Williams ◽  
Rick A. Boydston
Keyword(s):  
Weed Management ◽  
Yield Loss ◽  
Management Strategies ◽  
Field Studies ◽  
Functional Relationships ◽  
Weed Growth ◽  
Volunteer Potato ◽  
Tuber Production ◽  
Hand Weeding ◽  
Management Recommendations

Weed management systems in carrot are limited in part by a lack of fundamental understanding of crop–weed interactions. Irrigated field studies were conducted to quantify the effect of volunteer potato density and duration of interference on carrot yield and to determine relationships among weed density, duration of weed growth, and volunteer potato tuber production. A season-long volunteer potato density of 0.06 plants m−2produced from 150 to 230 g tubers m−2and resulted in an estimated 5% crop yield loss. At two volunteer potato plants m−2, the same level of crop loss was estimated with a duration of interference of 430 growing degree days (GDD), a time at which the weed had already produced 130 g tubers m−2. Volunteer potato height at the time of weed removal predicted carrot yield loss (R2= 0.77) and may be useful for timing of management strategies such as hand weeding. Functional relationships describing carrot–volunteer potato interactions provide simple information that is useful for developing weed management recommendations for carrot, a crop that relies on multiple tactics for managing weeds, and rotational crops that are negatively affected by persistence of volunteer potato.

scholarly journals Selection of Superior Genotypes in 37 Clones of Camu-Camu by Repetitivity Analysis

2017 ◽  
Vol 9 (6) ◽  
pp. 175
Author(s):  
Mario Pinedo Panduro ◽  
Edvan Alves Chagas ◽  
Elvis Paredes Davila ◽  
Carlos Abanto Rodriguez ◽  
Ricardo Bardales Lozano ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Statistical Analysis ◽  
Analysis Of Variance ◽  
Natural Populations ◽  
Reproductive Development ◽  
Fruit Weight ◽  
Peruvian Amazon ◽  
Superior Genotypes ◽  
Selection Of

In order to select camu-camu superior genotypes, a comparative of clones from natural populations, farmer plantations and an experimental field of the National Institute of Agrarian Innovation (INIA), was established in 2004 in varzea, at the Peruvian Amazon Research Institute (IIAP). Nine harvests between 2006 and 2016 have been evaluated, including variables in vegetative and reproductive development states. Statistical analysis was performed using the SPSS program for analysis of variance and SELEGEN REML/BLUP for repetitivity analysis of “fruit yield” (FY) and “fruit weight” (FW) with 5 and 4 measurements (years) respectively. For FY, a repetitivity index r = 0.117±0.07 was obtained with a selective precision of 0.63 and efficiency of 1.84 where clones 69, 48, 58, 50, 61, 13, 18, 29, 49 and 32, were selected in descending order of merit. For FW, r = 0.690±0.294 was obtained with selective precision of 0.948, efficiency of 1.14 and selection of clones 44, 13, 26, 23, 69, 64 22, 52, 27 and 8. As for the content in ascorbic acid, clones 48, 32 and 35 occupied the first places with more than 2000 mg of ascorbic acid/100 g. The selections achieved strengthened the pre-improvement work by conferring vigour y fiavility of a long term research.

Response of soya beans to planting date in south-eastern Queensland. II.* Vegetative and reproductive development

1974 ◽  
Vol 25 (5) ◽  
pp. 723 ◽  
Author(s):  
RJ Lawn ◽  
DE Byth
Keyword(s):  
Seed Yield ◽  
Vegetative Growth ◽  
Growth Period ◽  
Reproductive Development ◽  
Planting Date ◽  
Biological Efficiency ◽  
Vegetative Development ◽  
Planting Dates ◽  
Growing Period ◽  
Seed Yields

Vegetative and reproductive development of a range of soya bean cultivars was studied over a series of planting dates in both hill plots and row culture at Redland Bay, Qld. Responses in the extent of vegetative and reproductive development were related to changes in the phasic developmental patterns. The duration and extent of vegetative development for the various cultivar-planting date combinations were closely associated with the length of the period from planting to the cessation of flowering. Thus, vegetative growth was greatest for those planting dates which resulted in a delay in flowering and/or extended the flowering phase. Similarly, genetic lateness of maturity among cultivars was associated with more extensive vegetative development. Seed yield per unit area increased within each cultivar as the length of the growing period was extended until sufficient vegetative growth occurred to allow the formation of closed canopies under the particular agronomic conditions imposed. Further increases in the length of the period of vegetative growth failed to increase seed yield, and in some cases seed yields were actually reduced. Biological efficiency of seed production (BE) was negatively correlated with the length of the vegetative growth period. Differences in BE among cultivar-planting date combinations were large. It is suggested that maximization of seed yield will necessitate an optimum compromise between the degree of vegetative development and BE. Optimum plant arrangement will therefore vary, depending on the particular cultivar-planting date combination. ___________________ \*Part I, Aust. J. Agric. Res., 24: 67 (1973).

Effects of Limb Girdling on Growth and Development of Competing Fruit and Vegetative Tissues of Peach Trees

1984 ◽  
Vol 11 (2) ◽  
pp. 49 ◽  
Author(s):  
IR Dann ◽  
RA Wildes ◽  
DJ Chalmers
Keyword(s):  
Growth Regulators ◽  
Vegetative Growth ◽  
Aging Process ◽  
Prunus Persica ◽  
Soluble Sugars ◽  
Reproductive Development ◽  
Reproductive Growth ◽  
Potential Growth ◽  
Vegetative Tissues ◽  
Peach Trees

The distribution of current assimilates between competing zones of potential growth in the peach tree (Prunus persica (L.) Batsch) was studied using limb girdling, which altered the balance between reproductive growth and vegetative growth in a similar manner to the aging process. Fruit matured earlier, and leaf senescence and abscission were advanced in girdled limbs. which supported normal fruit loads but had only half the leaf area. Lateral growth and secondary thickening were reduced by 50% but vegetative growth approached normal rates at times when fruit growth was minimal, indicating that girdling reduced the ability of vegetative growth to compete with reproductive growth for assimilates. Starch and soluble sugars did not accumulate above the girdles. The data are consistent with the hypothesis that girdling alters the balance between endogenous growth regulators which favour either vegetative or reproductive development. We suggest that the initial effects on the girdled limb are attributable to accumulation of growth regulators produced above the girdle. The reduced flow of growth regulators to the roots eventually results in lowered levels of root-produced hormones which subsequently causes effects throughout the tree.

Investigating the Human Dimension of Weed Management: New Tools of the Trade

Weed Science ◽  
2010 ◽  
Vol 58 (4) ◽  
pp. 503-510 ◽  
Author(s):  
Doug Doohan ◽  
Robyn Wilson ◽  
Elizabeth Canales ◽  
Jason Parker
Keyword(s):  
Mental Models ◽  
Weed Management ◽  
Mental Model ◽  
Perceived Risk ◽  
Belief Systems ◽  
Human Dimension ◽  
Weed Species ◽  
Management Decisions ◽  
Weed Growth ◽  
Farmer Decision Making

The human dimension of weed management is most evident when farmers make decisions contrary to science-based recommendations. Why do farmers resist adopting practices that will delay herbicide resistance, or seem to ignore new weed species or biotypes until it is too late? Weed scientists for the most part have ignored such questions or considered them beyond their domain and expertise, continuing to focus instead on fundamental weed science and technology. Recent pressing concerns about widespread failure of herbicide-based weed management and acceptability of emerging technologies necessitates a closer look at farmer decision making and the role of weed scientists in that process. Here we present a circular risk-analysis framework characterized by regular interaction with and input from farmers to inform both research and on-farm risk-management decisions. The framework utilizes mental models to probe the deeply held beliefs of farmers regarding weeds and weed management. A mental model is a complex, often hidden web of perceptions and attitudes that govern how we understand and respond to the world. One's mental model may limit ability to develop new insights and adopt new ways of management, and is best assessed through structured, open-ended interviews that enable the investigator to exhaust the subjects inherent to a particular risk. Our assessment of farmer mental models demonstrated the fundamental attribution error whereby farmers attributed problems with weed management primarily to factors outside of their control, such as uncontrolled weed growth on neighboring properties and environmental factors. Farmers also identified specific processes that contribute to weed problems that were not identified by experts; specifically, the importance of floods and faulty herbicide applications in the spread of weeds. Conventional farmers expressed an overwhelming preference for controlling weeds with herbicides, a preference that was reinforced by their extreme dislike for weeds. These preferences reflect a typical inverse relationship between perceived risk and benefit, where an activity or entity we perceive as beneficial is by default perceived as low risk. This preference diminishes the ability of farmers to appreciate the risks associated with overreliance on herbicides. Likewise, conventional farmers saw great risk and little benefit in preventive measures for weed control. We expect that thorough two-way communication and a deeper understanding of farmer belief systems will facilitate the development of audience-specific outreach programs with an enhanced probability of affecting better weed management decisions.

Weed management options in transgenic stacked and non transgenic maize (Zea mays) hybrids-A review

2017 ◽  
Vol 38 (04) ◽  
Author(s):  
K. Sivagamy ◽  
C. Chinnusamy ◽  
P. Parasuraman
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Crop Growth ◽  
Control Programme ◽  
Growth And Yield ◽  
Growth Stages ◽  
Management Options ◽  
Maize Crop ◽  
Weed Growth ◽  
Vigorous Growth

Weeds are generally hardy species having fast growth, deep root system and capable of competing very efficiently with cultivated crops for the available resources and adversely affect the crop growth and yield. Weed management systems that rely on post emergence control assume that crops can tolerate competition for certain periods of time without suffering yield losses. Initial slow growth particularly at early crop growth stages and wider plant spacing of maize crop encourages fast and vigorous growth of weeds. It is of paramount importance that, competition from weeds must be minimized to achieve optimum yield. Among the different weed control methods, chemical method bears many advantages in suppressing weed growth and to get healthy and vigorous crop stand. Non-selective herbicide molecules with a variety of mode of action were discovered, developed and marketed for successful weed control programme.

Sign in / Sign up

Export Citation Format

Share Document