CRITICAL AUTUMN HARVEST PERIOD FOR ALFALFA IN THE ATLANTIC REGION BASED ON GROWING DEGREE-DAYS

1985 ◽  
Vol 65 (3) ◽  
pp. 573-580 ◽  
Author(s):  
A. BOOTSMA ◽  
MICHIO SUZUKI
Keyword(s):  
Medicago Sativa ◽  
Rest Period ◽  
Field Tests ◽  
Temporal Variations ◽  
Growing Degree Days ◽  
Degree Days ◽  
Atlantic Region ◽  
Medicago Sativa L ◽  
Starting Date ◽  
Food Reserves

Air temperature normals (1951–1980 period) were analyzed for over 200 locations in the Atlantic region to estimate spatial and temporal variations in the critical autumn period during which alfalfa (Medicago sativa L.) should not be harvested to allow plants to reach adequate winter hardiness by accumulating sufficient food reserves in the roots. Data are presented which show that the starting date of the critical harvest period could be estimated from the average date when 450 growing degree-days above 5 °C remain in autumn (F450). F450 compared well with starting dates determined experimentally in 3 yr of field tests at three locations in Ontario. F450 varied from before 10 Aug. in northwestern New Brunswick and parts of Newfoundland to after 4 Sept. in southwestern Nova Scotia. Annual differences in climate cause F450 to vary with a standard deviation of about 5–6 days at a given location. A zonation map describing spatial variation in the rest period was prepared as a general guide for cutting management.Key words: Alfalfa, Medicago sativa L., cutting management, winter survival, climate zonation

FORAGE CROP MATURITY ZONATION IN THE ATLANTIC REGION USING GROWING DEGREE-DAYS

1984 ◽  
Vol 64 (2) ◽  
pp. 329-338 ◽  
Author(s):  
A. BOOTSMA
Keyword(s):  
Medicago Sativa ◽  
Trifolium Pratense ◽  
Phleum Pratense ◽  
Growing Degree Days ◽  
Degree Days ◽  
Atlantic Region ◽  
Maturity Stages ◽  
Trifolium Pratense L ◽  
Medicago Sativa L ◽  
Phleum Pratense L

Accumulated growing degree-days above 5 °C (GDD) were used to estimate the average time of occurrence of maturity stages before first harvest in post seeding years for alfalfa (Medicago sativa L.), double cut red clover (Trifolium pratense L.) and timothy (Phleum pratense L.) in the Atlantic region of Canada. Maturity stages recommended for first cut were reached after an average accumulation of approximately 350, 400 and 450 GDD, depending upon the cultivar. Estimates of maturity dates based on the average air temperature (T) for May and June were highly correlated with annually observed dates of selected maturity stages [Formula: see text]. T was also used to estimate regional variation in maturity dates based on normals for the 1951–1980 period from 231 climate stations. Eight maturity zones (M1 to M8) were designated for the region. Estimated average dates when forage cultivars reach maturity stages recommended for first cut ranged from on or before 15 June–25 June in the Annapolis and Saint John River valleys to after mid-July in parts of Newfoundland.Key words: Medicago sativa L., Phleum pratense L., Trifolium pratense L., cutting date, temperature, zonation

scholarly journals Effect of cumulative growing degree day on accumulation of alfalfa (Medicago sativa L.) root reserve saccharides

2008 ◽  
Vol 56 (2) ◽  
pp. 81-86
Author(s):  
Josef Hakl ◽  
Jaromír Šantrůček ◽  
Pavel Fuksa ◽  
Josef Kalista
Keyword(s):  
Medicago Sativa ◽  
Starch Content ◽  
Life Sciences ◽  
Vegetation Period ◽  
Water Soluble ◽  
Research Station ◽  
Growing Degree Days ◽  
Degree Days ◽  
Degree Day ◽  
Medicago Sativa L

The aim of this study was to investigate the relation between growing degree day method and accumulation of root reserve saccharides before over wintering by alfalfa (Medicago sativa L.) in the condition of Czech Republic. In 2002–2004, the field experiment was conducted at the Research station of the Czech University of Life Sciences in central Bohemia. The interval between summer and last autumn harvest was 40–50 days or 60–70 days, respectively. These intervals were expressed as cumulative growing degree-days (GDD) for each year. The plants were sampled in each autumn with four replicates for each variant; the average depth of sampling was 150 mm. The weight of roots, amount of starch, and water soluble saccharides (WSC) per m2 was determined. The total accumulation of root reserve saccharides was determined mainly by conditions during all vegetation period. The length of the interval or cumulative GDD influenced only variation of this basic amount. The GDD was corresponded better with starch content whilst WSC was more related to length of the interval. In central Bohemia condition, the GDD 600–700 °C was preliminary determined for maximal accumulation of root reserve saccharides. The GDD above this level did not significantly increase the root reserve accumulation. For exact verify of this model, other experiments in more sites are needed.

Fall cutting management affects yield and persistence of alfalfa in Atlantic Canada

1999 ◽  
Vol 79 (1) ◽  
pp. 57-63 ◽  
Author(s):  
G. Bélanger ◽  
T. Kunelius ◽  
D. McKenzie ◽  
Y. Papadopoulos ◽  
B. Thomas ◽  
...  
Keyword(s):  
Medicago Sativa ◽  
The United States ◽  
Atlantic Canada ◽  
Growing Degree Days ◽  
Plant Mortality ◽  
Degree Days ◽  
The Third ◽  
Medicago Sativa L ◽  
Cutting Management ◽  
Final Harvest

The existing recommendation to avoid harvesting alfalfa during a critical fall rest period, based on calendar dates, is under review in Canada and adjacent areas of the United States. The effect on yield and persistence of four fall cutting management treatments (based on cumulative growing degree-days between harvests) was investigated for two cultivars of alfalfa (Medicago sativa L. 'Apica' and 'Oneida VR') at five sites in Atlantic Canada. The average seasonal DM yield for the five sites in the first production year was 1.6 to 2.3 t ha−1 greater with an additional harvest as compared with the two-harvest system (Truro, Nappan, Fredericton, and Charlottetown) and the one-harvest system in St. John's. Seasonal DM yield benefits were reduced over time; by the third production year, there was no increase in seasonal DM yield with an additional harvest. The seasonal DM yield increased with increasing the interval between the final harvest and the previous one. Taking an additional harvest resulted in higher winter plant mortality between the first and second production years in Truro and Nappan, and the third and fourth production years in St. John's. At the other two sites (Charlottetown and Fredericton), and for the first three production years in St. John's, winter plant mortality was unchanged with an additional harvest but regrowth potential in the following year was reduced. At the two sites that experienced a severe winter (Nappan and Truro), the cultivar Oneida VR was more adversely affected by the additional harvest than Apica. Our results indicate that in Atlantic Canada, taking an additional harvest increases the risk of winterkill. If an additional harvest is to be taken, increasing the interval between the final harvest and the previous one to at least 500 growing degree-days will decrease the risk of winterkill and might have a positive effect on next year's regrowth. Key words: Medicago sativa L., alfalfa, yield, persistence, harvest management, cultivar

Potential impacts of climate change on corn, soybeans and barley yields in Atlantic Canada

2005 ◽  
Vol 85 (2) ◽  
pp. 345-357 ◽  
Author(s):  
A. Bootsma ◽  
S. Gameda ◽  
D. W. McKenney
Keyword(s):  
Climate Change ◽  
Direct Effect ◽  
Crop Production ◽  
Field Trials ◽  
Growing Degree Days ◽  
Degree Days ◽  
Atlantic Region ◽  
Water Deficits ◽  
Heat Units ◽  
Impacts Of Climate Change

In this paper, relationships between agroclimatic indices and average yields of grain corn (Zea mays L.), soybeans (Glycine max L. Merr.) and barley (Hordeum vulgare L.) in field trials conducted in eastern Canada are explored and then used to estimate potential impacts of climate change scenarios on anticipated average yields and total production of these commodities for the Atlantic region for the 2040 to 2069 period. Average yields of grain corn and soybeans were highly correlated (R2 = 0.86 and 0.74, respectively) with average available crop heat units (CHU), with yields increasing by about 0.006 t ha-1 CHU-1 for corn and 0.0013 t ha-1 CHU-1 for soybeans. The explained variance was not improved significantly when water deficit (DEFICIT) was included as an independent variable in regression. Correlations between average yields of barley and effective growing degree-days (EGDD) were low (R2 ≤ 0.26) and negative, i.e., there was a tendency for slightly lower yields at higher EGDD values. Including a second-order polynomial for DEFICIT in the regression increased the R2 to ≥ 0.58, indicating a tendency for lower barley yields in areas with high water deficits and with water surpluses. Based on a range of available heat units projected by multiple General Circulation Model (GCM) experiments, average yields achievable in field trials could increase by about 2.6 to 7.5 t ha-1 (40 to 115%) for corn, and by 0.6 to 1.5 t ha-1 (21 to 50%) for soybeans by 2040 to 2069, not including the direct effect of increased atmospheric CO2 concentrations, advances in plant breeding and crop production practices or changes in impacts of weeds, insects and diseases on yield. Anticipated reductions in barley yields are likely to be more than offset by the direct effect of increased CO2 concentrations. As a result of changes in potential yields, there will likely be significant shifts away from production of barley to high-energy and high-protein crops (corn and soybeans) that are better adapted to the warmer climate. However, barley and other small grain cereals will likely remain as important crops as they are very suited for rotation with potatoes. There is a need to evaluate the potential environmental impacts of these possible shifts in crop production, particularly with respect to soil erosion in the region. Key words: Crop heat units, growing degree-days, water deficits, crop yields, climate change, Atlantic region

scholarly journals MODELING THE OCCURRENCE OF THE FLOWERING PEAK OF MACADAMIA NUT (MACADAMIA INTEGRIFOLIA)

HortScience ◽  
1992 ◽  
Vol 27 (12) ◽  
pp. 1262b-1262
Author(s):  
Sam-Gwang Hwang ◽  
Kent D. Kobayashi ◽  
Mike A. Nagao
Keyword(s):  
Minimum Temperature ◽  
Proper Time ◽  
Maximum Temperature ◽  
Total Solar Radiation ◽  
Growing Degree Days ◽  
Degree Days ◽  
Macadamia Integrifolia ◽  
Flowering Season ◽  
Macadamia Nut ◽  
Starting Date

The objective of this study was to develop models to predict the occurrence of the flowering peak of macadamia nut (Macadamia integrifolia). At Hilo and Kona, weather and `Ikaika' flowering data were collected. The best model that described the time from the starting date of the flowering season to the highest flowering peak was days = 249.15 + 0.12 (total growing degree days) - 5.81 (maximum temperature) - 6.26 (minimum temperature). The model predicted the highest peak 4 days before it occurred at Hilo and 4 days after it occurred at Kona. Two statistical models, one for each location, were developed to predict the time from the starting date of the flowering season to the first peak. At Hilo, the best model was days = 118.61 - 0.11 (total growing degree days) + 0.000168 (total solar radiation). The model predicted the first peak 1 day before it occurred in the field. The best model at Kona was days = (-156.34) + 12.67 (minimum temperature) + 0.01 (total growing degree days). The model predicted the first peak on the day it occurred in the field. These models may aid growers in predicting the flowering peak so that bees can be brought into orchards at the proper time to increase cross-pollination.

Impacts of potential climate change on selected agroclimatic indices in Atlantic Canada

2005 ◽  
Vol 85 (2) ◽  
pp. 329-343 ◽  
Author(s):  
A. Bootsma ◽  
S. Gameda and D.W. McKenney
Keyword(s):  
Climate Change ◽  
Statistical Downscaling ◽  
Growing Degree Days ◽  
Climate Change Scenarios ◽  
Degree Days ◽  
Atlantic Region ◽  
Water Deficits ◽  
Heat Units ◽  
Agricultural Areas ◽  
The Impact

Agroclimatic indices (heat units and water deficits) were determined for the Atlantic region of Canada for a baseline climate (1961 to 1990 period) and for two future time periods (2010 to 2039 and 2040 to 2069). Climate scenarios for the future periods were primarily based on outputs from the Canadian General Circulation Model (GCM) that included the effects of aerosols (CGCMI-A), but variability introduced by multiple GCM experiments was also examined. Climatic data for all three periods were interpolated to a grid of about 10 to 15 km. Agroclimatic indices were computed and mapped based on the gridded data. Based on CGCMI-A scenarios interpolated to the fine grid, average crop heat units (CHU) would increase by 300 to 500 CHU for the 2010 to 2039 period and by 500 to 700 CHU for the 2040 to 2069 period in the main agricultural areas of the Atlantic region. However, increases in CHU for the 2040 to 2069 period typically varied from 450 to 1650 units in these regions when variability among GCM experiments was considered, resulting in a projected range of 2650 to 4000 available CHU. Effective growing degree-days above 5°C (EGDD) typically increased by about 400 units for the 2040 to 2069 period in the main agricultural areas, resulting in available EGDD from 1800 to over 2000 units. Uncertainty introduced by multiple GCMs increased the range from 1700 to 2700 EGDD. A decrease in heat units (cooling) is anticipated along part of the coast of Labrador. Anticipated changes in water deficits (DEFICIT), defined as the amount by which potential evapotranspiration exceeded precipitation over the growing season, typically ranged from +50 to −50 mm for both periods, but this range widened from +50 to −100 mm when variability among GCM experiments was considered. The greatest increases in deficits were expected in the central region of New Brunswick for the 2040 to 2069 period. Our interpolation procedures estimated mean winter and summer temperature changes that were 1.4°C on average lower than a statistical downscaling procedure (SDSM) for four locations. Increases in precipitation during summer and autumn averaged 20% less than SDSM. During periods when SDSM estimated relatively small changes in temperature or precipitation, our interpolation procedure tended to produce changes that were larger than SDSM. Additional investigations would be beneficial that explore the impact of a range of scenarios from other GCM models, other downscaling methods and the potential effects of change in climate variability on these agroclimatic indices. Potential impacts of these changes on crop yields and production in the region also need to be explored. Key words: Crop heat units, effective growing degree-days, water deficits, climate change scenarios, statistical downscaling, spatial interpolation

Effects of harvesting systems on yield, persistence, and nutritive value of alfalfa

1992 ◽  
Vol 72 (3) ◽  
pp. 793-799 ◽  
Author(s):  
G. Bélanger ◽  
J. E. Richards ◽  
R. E. McQueen
Keyword(s):  
Medicago Sativa ◽  
Nutritive Value ◽  
Rest Period ◽  
Growth Period ◽  
Harvest Management ◽  
The Third ◽  
Stage Of Development ◽  
Potassium Fertilization ◽  
Harvesting Systems ◽  
Medicago Sativa L

The number of annual harvests and the interval between harvests affect DM yield, persistence, and nutritive value of alfalfa (Medicago sativa L.). The effects of harvesting alfalfa three times annually, with the intervals between harvests varied and with the third harvest taken prior to, during, or after the critical fall rest period, were investigated from 1985 to 1988 on a field of alfalfa established in 1984. Seven harvesting systems, comprising three harvests with varied regrowth intervals and a two-harvest system, were studied along with two rates of potassium fertilization. Harvesting alfalfa three times a year, with the third harvest taken during or after the critical fall rest period, produced the largest yields of DM, digestible DM, and crude protein. Dry matter yield was not reduced in three-harvest systems when the third harvest was taken during the critical fall rest period, provided there was an interval of approximately 500 growing degree-days between second and third harvests. Taking the first harvest at the early bud stage of development instead of the early bloom stage reduced annual DM yields. Increasing annual potassium fertilization from 200 to 400 kg K ha−1 did not affect DM yield or persistence under any harvesting system. Harvesting management of alfalfa in the fall should be based on the duration of the growth period between the second and third harvests instead of a critical fall rest period based on calendar dates.Key words: Medicago sativa L., yield, nutritive value, persistence, harvest management, K fertilization

INFLUENCE DES RÉGIMES D’EXPLOITATION SUR LE RENDEMENT, LE PEUPLEMENT, LES RÉSERVES NUTRITIVES ET LA COMPOSITION CHIMIQUE DE LA LUZERNE

1985 ◽  
Vol 65 (3) ◽  
pp. 553-564 ◽  
Author(s):  
P. GERVAIS ◽  
M. BILODEAU
Keyword(s):  
Chemical Composition ◽  
Medicago Sativa ◽  
Dry Matter ◽  
Composition Chimique ◽  
The Third ◽  
Medicago Sativa L ◽  
Food Reserves

A 3-yr study on harvesting management applied to alfalfa (Medicago sativa L.) shows that a three-cut system, the last cut taken in October, yielded significantly more dry matter than a two-cut system. The latter system, however, gave a more uniform production throughout the years and maintained the stand at the highest level. Fall cuttings, taken at weekly intervals from the end of August to the end of September, reduced both the yield and the stand, the earliest cuttings being most harmful. October cuttings showed little effect on the productivity of alfalfa. The percentages of non structural carbohydrates stored in the roots on 1 November increased only slightly with the delay in taking the third cut in September. The accumulation of the food reserves was favored most by the two-cut system and the three-cut system with the last cut taken at mid-October. The influence of the harvesting regimes on the chemical composition of the forage is also discussed.Key words: Alfalfa, harvesting management, yield, persistence, chemical composition, food reserves

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

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