Regrowth of crested wheatgrass (Agropyron cristatum [L.] Gaertn.) following defoliation

1999 ◽  
Vol 79 (4) ◽  
pp. 557-563 ◽  
Author(s):  
J. T. Romo ◽  
T. Harrison
Keyword(s):  
Rest Period ◽  
Growing Season ◽  
Agropyron Cristatum ◽  
Annual Production ◽  
Growing Degree Days ◽  
Degree Days ◽  
Crested Wheatgrass ◽  
Total Annual Production ◽  
Lag Period ◽  
Time Required

Effects of defoliation of crested wheatgrass (Agropyron cristatum [L.] Gaertn.) on the amount of time required to reach peak regrowth, the lag period for regrowth to begin, regrowth biomass, tiller survival and replacement, and carryover effects of defoliation the following year were investigated. Regrowth of crested wheatgrass was determined during the summers of 1990, 1991 and 1992 in central Saskatchewan following a single defoliation to a 5-cm stubble height at eight stages of growth. Crested wheatgrass regrew 54–130 g m−2 of biomass when defoliated tillers had ≤3.6 leaves. Regrowth began accumulating within 3–53 growing degree-days (GDD) and peaked in 705–875 GDD. Rates of leaf development after defoliation (218–252 GDD phyllochron−1) equaled or were faster than control (218–330 GDD phyllochron−1). Regrowth biomass accounted for 35–76% of total annual production. Total annual production was greatest when plants were defoliated during vegetative growth or at peak growth. In 1991 and 1992, etiolated growth in the spring following defoliation was reduced by defoliation in the previous year. Tiller replacement was not affected by defoliation and averaged 1.2 tillers tiller−1 (SE = 0.1) in 1991 and 1.5 tillers tiller−1 (SE = 0.1) in 1992. Two periods of grazing can be expected from crested wheatgrass if it is grazed when tillers have ≤3.6 leaves; however, the impacts of a second grazing must be determined. If crested wheatgrass is grazed late in the growing season, only one period of grazing can be expected, and production will likely be less the following growing season, necessitating a rest period for plants to regain their production potential. Key words: Crested wheatgrass, defoliation, grazing management, growing degree-days, phyllochron, regrowth

CHLOROGENIC ACID CONTENT OF SUNFLOWER SEED FLOUR AS AFFECTED BY SEEDING AND HARVEST DATE

1976 ◽  
Vol 56 (4) ◽  
pp. 901-905 ◽  
Author(s):  
D. G. DORRELL
Keyword(s):  
Chlorogenic Acid ◽  
Acid Content ◽  
Vegetative Growth ◽  
Sunflower Seed ◽  
Growing Season ◽  
Growing Degree Days ◽  
Degree Days ◽  
Normal Field ◽  
Seed Flour ◽  
Seeding Date

The effect of seeding date on the chlorogenic acid content of sunflower seed flour was determined by seeding the cultivars Krasnodarets and Peredovik at seven dates, starting on 14 May, over 3 yr. Sequential plantings were made at increments of approximately 70 growing degree days (base = 5.6 C). Plants were harvested at normal field maturity. The time and rate of deposition of chlorogenic acid was determined by harvesting plants at 7-day intervals from 21 to 49 days after flowering. The seeds were dehulled and defatted before determining the chlorogenic acid content of the flour. Chlorogenic acid content declined steadily from an average of 4.22% for the first seeding to 3.30% for the last seeding. About one-half of the total chlorogenic acid was present 21 days after flowering. Deposition continued rapidly for the next 14 days then the level began to stabilize. Delay in seeding tended to shorten the period of vegetative growth and shift the deposition of chlorogenic acid to a cooler portion of the growing season. It is suggested that a combination of these factors caused the reduction in chlorogenic acid content of sunflower flour.

Timing and rate of bud formation in Pinus resinosa

1971 ◽  
Vol 49 (10) ◽  
pp. 1821-1832 ◽  
Author(s):  
Edward Sucoff
Keyword(s):  
Quantitative Data ◽  
Shoot Growth ◽  
Pinus Resinosa ◽  
Growing Season ◽  
Axillary Buds ◽  
Growing Degree Days ◽  
Degree Days ◽  
Bud Formation ◽  
Late Season ◽  
Apical Dome

During the 1969 and 1970 growing season buds were collected almost weekly from matched trees in northeastern Minnesota. Cataphyll primordia for the year n + 1 shoot began forming at the time that internodes in the year n shoot started elongating (late April) and continued forming until early September. Primordia for axillary buds started forming about 2 months later and stopped forming at the same time as cataphylls. The size and deposition activity of the apical dome simultaneously increased during the early growing season and decreased during the late season. The maximum rates in July were over nine cataphylls per day.Rate of cataphyll deposition paralleled elongation of the needles on subtending shoots. Forty to fifty percent of the cataphylls had been formed when shoot growth was 95% complete. Although the bulk of the depositions occurred earlier in 1970, when growing degree days were used as the clock, the 2 years were similar.The results provide quantitative data to complement the histologic emphasis of previous studies.

Spatial Analysis of Climate-Viticulture Indices for the Eastern United States

2016 ◽  
Vol 7 (4) ◽  
pp. 23-37 ◽  
Author(s):  
Rosalyn Francine MacCracken ◽  
Paul R. Houser
Keyword(s):  
United States ◽  
Spatial Analysis ◽  
Growing Season ◽  
Climate Indices ◽  
Growing Degree Days ◽  
Eastern United States ◽  
Degree Days ◽  
The Us ◽  
Resolution Dataset ◽  
Effective Degree

This study characterizes the climate structure in the Eastern United States for suitability of winegrape growth. For this study, the Eastern US is defined as the 44 contiguous Eastern most states. This excludes the premium wine growing states of California, Washington, Oregon and Idaho. For this characterization, a comparative study is performed on the four commonly used climate-viticulture indices (i.e., Average Growing Season Temperature, Growing Degree Days, Heliothermal Index and Biologically Effective Degree Days), and a new climate-viticulture index, the Modified-GSTavg (Mod-GSTavg). This is accomplished using the 1971 – 2000 PRISM 800-meter resolution dataset of climate temperature normal for the study area of 44 states and 62 American Viticultural Areas across the Eastern United States. The results revealed that all the climate indices have similar spatial patterns throughout the US with varying magnitudes and degrees of suitability.

scholarly journals Long-Term Trends in Air Temperature Distribution and Extremes, Growing Degree‐Days, and Spring and Fall Frosts for Climate Impact Assessments on Agricultural Practices in Nebraska

2012 ◽  
Vol 51 (11) ◽  
pp. 2060-2073 ◽  
Author(s):  
Kari E. Skaggs ◽  
Suat Irmak
Keyword(s):  
Air Temperature ◽  
Central City ◽  
Agricultural Practices ◽  
Growing Season ◽  
Growing Degree Days ◽  
Degree Days ◽  
Temperature Changes ◽  
Growing Season Length ◽  
Average Maximum

AbstractAir temperature influences agricultural practices and production outcomes, making detailed quantifications of temperature changes necessary for potential positive and negative effects on agricultural management practices to be exploited or mitigated. Temperature trends of long-term data for five agricultural locations, ranging from the subhumid eastern to the semiarid western parts of Nebraska, were studied to determine local temperature changes and their potential effects on agricultural practices. The study quantified trends in annual and monthly average maximum and minimum air temperature (Tmax and Tmin), daily temperature range (DTR), total growing degree-days, extreme temperatures, growing‐season dates and lengths, and temperature distributions for five heavily agricultural areas of Nebraska: Alliance, Central City, Culbertson, Fremont, and Hastings. July and August were the months with the greatest decreases in Tmax for the central part of Nebraska—Culbertson, Hastings, and Central City. Alliance, Culbertson, and Fremont had year-round decreases in DTR. Central City and Hastings experienced growing‐season decreases in DTR. Increases in growing‐season length occurred at rates of 14.3, 16.7, and 11.9 days century−1 for Alliance, Central City, and Fremont, respectively. At Hastings, moderately earlier last spring frost (LS) at a rate of 6.6 days century−1 was offset by an earlier (2.7 days century−1) first fall frost (FF), resulting in only a 3.8 days century−1 longer growing season. There were only slight changes in LS and FF dates of around 2 days earlier and 1 day later per century, respectively, for Culbertson.

scholarly journals Modeling Cotton Growth and Yield Response to Irrigation Practices for Thermally Limited Growing Seasons in Kansas

2021 ◽  
Vol 64 (1) ◽  
pp. 1-12
Author(s):  
R. Louis Baumhardt ◽  
Lucas A. Haag ◽  
Prasanna H. Gowda ◽  
Robert C. Schwartz ◽  
Gary W. Marek ◽  
...  
Keyword(s):  
Deficit Irrigation ◽  
Growing Season ◽  
Lint Yield ◽  
Growth And Yield ◽  
Yield Response ◽  
Growing Degree Days ◽  
Cotton Yield ◽  
Degree Days ◽  
Center Pivot ◽  
Use Efficiency

HighlightsLater planting and greater site elevation or latitude decreased seasonal growing degree days and cotton yield in Kansas.Higher irrigation capacity (rate) usually increased lint yield, which was probably due to increased early boll load.Strategies for splitting land allocations between high irrigation rates and dryland did not increase production.Cotton may reduce irrigation withdrawals from the Ogallala aquifer, but the Kansas growing season limits production.Abstract. Precipitation in the western Great Plains averages about 450 mm, varying little with latitude and providing 40% to 80% of potential crop evapotranspiration (ETc). Supplemental irrigation is required to fully meet crop water demand, but the Ogallala or High Plains aquifer is essentially non-recharging south of Nebraska. Pumping water from this aquifer draws down water tables, leading to reduced water availability and deficit irrigation to produce an alternate crop such as cotton (Gossypium hirsutum L.) with a lower peak water demand than corn (Zea mays L.). Our objective was to compare simulated cotton yield response to emergence date, irrigation capacity, and application period at three western Kansas locations (Colby, Tribune, and Garden City) with varying seasonal energy or cumulative growing degree days (CGDD) and compare split center pivot deficit irrigation strategies with a fixed water supply (i.e., where portions of the center pivot land area are managed with different irrigation strategies). We used actual 1961-2000 location weather records with the GOSSYM simulation model to estimate yields of cotton planted into soil at 50% plant-available water for three emergence dates (DOY 145, 152, and 159) and all combinations of irrigation period (0, 4, 6, 8, and 10 weeks beginning at first square) and capacity (2.5, 3.75, and 5.0 mm d-1). Simulated lint yield and its ratio to ETc, or water use efficiency (WUE), consistently decreased with delayed planting (emergence) as location elevation or latitude increased due to effects on growing season CGDD. Depending on location, simulated cotton lint consistently increased (p = 0.05) for scenarios with increasing irrigation capacity, which promoted greater early season boll load, but not for durations exceeding 4 to 6 weeks, probably because later irrigation and fruiting did not complete maturation during the short growing season. Cotton WUE generally increased, with greater yields resulting from earlier emergence and early high-capacity irrigation. We calculated lower WUE where irrigation promoted vigorous growth with added fruiting forms that delayed maturation and reduced the fraction of open bolls. The irrigation strategy of focusing water at higher capacities on a portion of the center pivot in combination with the dryland balance did not increase net yields significantly at any location because the available seasonal energy limited potential crop growth and yield response to irrigation. However, the overall net lint yield was numerically larger for focused irrigation strategies at the southwest Kansas location (Garden City). Based on lint yields simulated under uniform or split center pivot deficit irrigation, we conclude that cotton is poorly suited as an alternative crop for central western and northwestern Kansas because of limited growing season CGDD. Keywords: Cotton, Crop simulation, Deficit irrigation, Evapotranspiration, Irrigation capacity, Split center pivot irrigation, Water use efficiency, Yield limiting factors.

scholarly journals Analysis of viticulture region climate structure and suitability in New Zealand

OENO One ◽  
2012 ◽  
Vol 46 (3) ◽  
pp. 149 ◽  
Author(s):  
Jon D. Anderson ◽  
Gregory V. Jones ◽  
Andrew Tait ◽  
Andrew Hall ◽  
Michael C.T. Trought
Keyword(s):  
New Zealand ◽  
Growing Season ◽  
Climate Indices ◽  
Growing Degree Days ◽  
Methodological Issues ◽  
Warm Climate ◽  
Degree Days ◽  
Average Temperature ◽  
Climate Suitability ◽  
Two Indices

<p style="text-align: justify;"><strong>Aims</strong>: This research analyzes four climate indices derived from gridded, interpolated data to assess New Zealand’s climate structure and variation among wine regions.</p><p style="text-align: justify;"><strong>Methods and results</strong>: High resolution gridded data based on 1971-2000 climate normals was used to characterize climate indices depicting viticultural suitability in a geographic information system. The statistical properties of each index were assessed over 21 New Zealand viticulture regions. The results show predominately cool to moderately warm climate suitability in New Zealand, comparable to many European and United States regions. While many viticulture regions have one primary class of suitability, variability of climate within regions can be significant, with some regions containing two to four climate classes, making them suitable for a greater range of cultivars.</p><p style="text-align: justify;"><strong>Conclusion</strong>: While the indices depict broad patterns expected over New Zealand, both within and between region variations can be substantial among the indices. However, two indices, Growing Season Average Temperature (GST) and Growing Degree-Days (GDD), are functionally identical, but GST is easier to calculate and overcomes many methodological issues in GDD.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This research provides the basis for evaluating general suitability for viticulture in New Zealand, assists comparisons between viticulture regions in New Zealand and worldwide, and offers growers measures of assessing appropriate cultivars and sites.</p>

Redstem Filaree (Erodium cicutarium) Development and Productivity Under Noncompetitive Conditions

1998 ◽  
Vol 12 (4) ◽  
pp. 590-594 ◽  
Author(s):  
Robert E. Blackshaw ◽  
K. Neil Harker
Keyword(s):  
Integrated Management ◽  
Management Strategies ◽  
Growing Season ◽  
Yield Response ◽  
Growing Degree Days ◽  
Degree Days ◽  
Canadian Prairies ◽  
Erodium Cicutarium ◽  
Winter Annuals ◽  
Emergence Date

Redstem filaree is becoming widespread and abundant on the Canadian prairies. A field study was conducted to determine the growth, development, and seed yield response of redstem filaree when grown under noncropped conditions and planted at various dates throughout the growing season in Alberta. Redstem filaree emerged within 7 to 13 d of planting with an accumulated 57 to 134 growing degree days (GDD). Flowering occurred within 46 to 65 d (327 to 779 GDD) of planting. Plants that emerged in August or later did not flower in that season and survived as winter annuals. Spring-emerging redstem filaree plants matured within 79 to 100 d (729 to 1,193 GDD). Plants that emerged in May and June attained more biomass and produced threefold more seeds than plants that emerged in July or later. Redstem filaree seed production ranged from 2,400 to 9,900 seeds/plant depending on emergence date and environmental conditions. Information from this study will assist in developing integrated management strategies for this increasingly important weed.

Influence of establishment timing on growth and fecundity of two itchgrass (Rottboellia cochinchinensis) biotypes grown in Louisiana

Weed Science ◽  
2020 ◽  
Vol 68 (4) ◽  
pp. 418-425
Author(s):  
Douglas J. Spaunhorst
Keyword(s):  
Yield Loss ◽  
Seedling Emergence ◽  
Common Garden ◽  
Growing Season ◽  
Growing Degree Days ◽  
Initial Growth ◽  
Common Garden Experiment ◽  
Degree Days ◽  
Humid Climate ◽  
Rottboellia Cochinchinensis

AbstractItchgrass [Rottboellia cochinchinensis (Lour.) W.D. Clayton] is among the most troublesome weeds in subtropical climates where sugarcane (Saccharum spp. interspecific hybrids) is cultivated. Two R. cochinchinensis biotypes commonly infest sugarcane in Louisiana. The Louisiana-1 biotype is daylength neutral, but Louisiana-2 flowered when daylength decreased to 13 h. Coupled with biotype diversity, seedling emergence has been reported to occur earlier in the growing season, as sugarcane emerged from winter dormancy. Both R. cochinchinensis biotypes were established in a common garden experiment in Louisiana during periods of sugarcane development and field preparation to simulate discontinuous emergence. Plant height and raceme production were recorded weekly for each biotype and establishment timing; aboveground biomass was harvested in autumn. Louisiana’s subtropical humid climate stimulated rapid plant growth that typically began in May and persisted through September. Without sugarcane competition, maximum R. cochinchinensis heights for Louisiana-1 and Louisiana-2 were 206 and 179 cm and growing degree days to 20-cm height in 2017 ranged from 546 to 832 and 865 to 1,160, respectively. Slower initial growth reported with Louisiana-2 would allow more time for growers to treat escaped plants with POST herbicides. Total raceme production, by autumn, was zero for Louisiana-2 established in June or later, but Louisiana-1 established in June produced up to 202 racemes. The present study demonstrated the importance of managing the Louisiana-2 biotype in March and April to limit seed production, but fields infested with Louisiana-1 were at greater risk for potential crop yield loss, because plants produced high quantities of seed when established over a wide period of time.

In situ emergence timing of large and small crabgrass in residential turfgrass of southern Ontario

2013 ◽  
Vol 93 (3) ◽  
pp. 503-509 ◽  
Author(s):  
Fawn A. Turner ◽  
Rene C. Van Acker
Keyword(s):  
Growing Season ◽  
Growing Degree Days ◽  
Degree Days ◽  
Cool Season ◽  
Digitaria Sanguinalis ◽  
Reliable Measure ◽  
Southern Ontario ◽  
Management Approaches ◽  
Large Crabgrass

Turner, F. A. and Van Acker, R. C. 2013. In situ emergence timing of large and small crabgrass in residential turfgrass of southern Ontario. Can. J. Plant Sci. 93: 503–509. Large, Digitaria sanguinalis (L.) Scop., and small, Digitaria ischaemum (Schreb.) ex Muhl., crabgrass are problem weeds in turfgrass. Due to an increasing number of cosmetic pesticide bans in Canada there is a need to better understand the biology and ecology of crabgrass in order to develop and hone management approaches. The assessment of crabgrass recruitment timing is particularly relevant to its management, including the timing of alternative herbicide applications. This study focused on determining the emergence timing of established populations of large and small crabgrass in typical residential turfgrass stands in southern Ontario. Small crabgrass emerged earlier than large crabgrass at 346 and 515 growing degree days (GDD), respectively. In typical southern Ontario lawns both small and large crabgrass emerge after cool-season turfgrass has established and emergence continues late into the summer. For example, even within the last 2 wk of July we observed over 700 seedlings m–2 of large crabgrass emerging in some observation plots. This study also confirmed that small crabgrass emerges earlier than large crabgrass. There was a greater difference in emergence timing between species rather than among sites, suggesting that it is important to differentiate between species when timing management approaches. The late and prolonged emergence of crabgrass makes residential lawns that are not well maintained susceptible to infestation for a long portion of the growing season. This study also demonstrated that cumulative GDD may be a reliable measure for tracking crabgrass emergence suggesting, that it could be used as a tool for management, including the application of alternative herbicides. This study reinforces the importance of maintaining healthy and dense turf stands throughout the season as a deterrent to crabgrass infestations.

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