Crop Heat Units Research Articles

The potential of growing soybean in Saskatchewan and its irrigation water needs under climate change scenarios—a modelling study

The soybean industry in Canada is seeking opportunities to expand cultivation due to economic and environmental benefits of growing soybean. Climate projections indicate that soybean expansion into Saskatchewan would be possible with the increases in the available crop heat units under a future warmer climate; however, crop water availability could limit yields. Using a crop growth model, we simulated soybean yields within the Canadian Regional Agricultural Model regions in Saskatchewan for the near-term (2030s), mid-term (2050s), and distant future (2070s) periods under different climate scenarios. Soybean yields were simulated without water stress (potential yield), with water stress (rainfed yield), and under full and partial irrigation scenarios. Irrigation water needs were estimated under the irrigation scenarios and irrigation water availability was discussed. Our results suggest that reasonable and likely more profitable yields (∼2000–2500 kg ha−1) can be achieved under rainfed conditions in the Black soil zone neighbouring Manitoba but soybean production would be less favourable in the Dark Brown soil zone and least favourable in the Brown soil zone. Northeastern regions in the Black soil zone were found to be suitable for growing soybean cultivars in the maturity group (MG) 0 in the distant future and MG 00 in the mid-term under the medium–high greenhouse gas emission scenarios. Soybean would still not be suitable in the northwestern region. Our results indicate that regions in central Saskatchewan requiring 120–170 mm of irrigation are more likely to benefit from the proposed Lake Diefenbaker Irrigation Projects in the future.

OAC Stirling soybean

OAC Stirling is a semi-determinate large-seeded food-grade soybean [ Glycine max (L.) Merr.] cultivar with high yield potential, high seed protein concentration, and resistance to soybean cyst nematode. OAC Stirling is developed and recommended for soybean growing areas in southwestern Ontario with 3100 or greater crop heat units and has a relative maturity of 2.3.

OAC Union soybean

The OAC Union cultivar of soybean [ Glycine max (L.) Merr.] is semi-determinate, has large seeds suitable for food-grade purposes, and offers high yield potential with elevated concentrations of seed protein and oil. Additionally, it displays resistance to soybean cyst nematode. OAC Union is developed and recommended for soybean-growing areas in southwestern Ontario with 2800 or greater crop heat units and has a relative maturity of 1.4.

Climate conditions in the near-term, mid-term and distant future for growing soybeans in Canada

The soybean industry in Canada aimed to extensively expand soybean production to benefit from new early-maturing varieties and the warming climate. However, setbacks in the soybean industry since 2017 demonstrated the impacts of climate risk and global market uncertainty. Therefore, a better understanding of future climate conditions that will impact soybean growth in Canada is needed for decision-making in the sector, such as prioritizing regions for expansion and developing climate change adaptation strategies through either agronomic management practices or breeding new cultivars. Based on climate projections from a set of global climate models, we analyzed climate conditions for growing soybeans, including growing season start, crop heat units, precipitation, precipitation deficits and climate extremes, in the near-term (2030s), the mid-term (2050s) and the distant future (2070s). We found that a future warmer climate with an increase of 1.6, 2.8 and 4.1 °C in the growing season (May–September) mean temperature averaged over Canada’s land area in the near-term, mid-term and distant future under SSP3-7.0 would favour the expansion of soybean production further north and west. However, an increase of approximately 200 mm in precipitation deficits on the semiarid Canadian Prairies in the mid-term would constrain soybean production unless irrigation could be introduced. Heat- and drought-tolerant cultivars should be developed to adapt soybean production to a changing climate, in addition to the adoption of late-maturing cultivars that would benefit from the lengthened growing season and increased crop heat units.

Analysis of Relationship between Soybean Relative Maturity Group, Crop Heat Units and ≥10 °C Active Accumulated Temperature

Crop heat units (CHU) and ≥10 °C active accumulated temperature (≥10 °C AAT) are important indexes to quantify the effects of temperature on soybean development. The relative maturity group (RMG) is widely used in the classification of different soybean varieties. However, CHU and ≥10 °C AAT (AAT) were applied in Canada and northeastern China, respectively, and the relationships among CHU, AAT and RMG are poorly documented. The objective of this study is to analyze the conversion function among CHU, AAT and RMG based on two datasets. The first dataset was obtained to analyze the relationship between RMG and AAT in 395 varieties in Northeast China. The second dataset was obtained to calculate the relationship between CHU and AAT at 95 weather stations based on 30-year climatic data (1990–2019). The results showed that both relationships were significantly and positively correlated, and the R-square of these relationships were 0.90 and 0.98, respectively. The distribution of CHU or AAT in the Northeast is proposed. These results can be extensively used for predicting the CHU or AAT of soybean cultivars given the known RMG, thus determining the adaptation zone as well as the growth stage of agricultural practices and responses to heat accumulation. The conclusion of the current study is expected to be widely adopted by soybean regionalization and germplasm exchanges throughout the world.

Soybean yield loss from delayed postemergence herbicide application based on weed height, days after emergence, accumulated crop heat units, and soybean growth stage

AbstractLimited information exists on the critical time of weed removal (CTWR) with the currently used soybean cultivars in Ontario. A study consisting of eight field experiments was conducted from 2017 to 2019 in Ontario, Canada, to determine the impact of delayed postemergence (POST) herbicide application on soybean yield based on average weed height at application, days after crop emergence (DAE), accumulated crop heat units (CHU) from the date of planting, and soybean growth stage. The regression model estimated the weed size at herbicide application that led to 1%, 2.5%, and 5% yield loss in soybean was 9, 14, and 20 cm under low weed density (averaging 73 to 134 plants m−2) and 3, 4, and 6 cm under high weed density (143 to 153 plants m−2) conditions, respectively. The estimated DAE at herbicide application time that led to 2.5%, 5%, 10%, and 25% yield loss in soybean was 24, 30, 37, and 53 DAE under low weed density and 8, 10, 14, and 23 DAE under high weed density, respectively. The predicted crop stage at herbicide application that resulted in 2.5%, 5%, 10%, and 25% yield loss in soybean was V4, V5, R2, and R5 under low weed density and VE, VC, V1, and V4 under high weed density, respectively. This study concludes that soybean yield loss is influenced by the weed density (low vs/high) and the time of the first POST herbicide application. When the first POST herbicide application was delayed until soybean was at the V2 stage the monetary loss was Can$20.46 and Can$221.20 ha−1 in low and high weed-density environments, respectively.

Impact of delayed postemergence herbicide application on corn yield based on weed height, days after emergence, accumulated crop heat units, and corn growth stage

AbstractNine field experiments were conducted from 2017 to 2019 in Ontario to determine the impact of early weed interference on corn yield based on corn growth stage, days after emergence (DAE), accumulated crop heat units (CHU), and weed size. The predicted weed size at herbicide application that resulted in a 1%, 2.5%, 5%, 10%, 25%, and 50% yield loss in corn was estimated to be 1, 4, 11, 53, non-estimable (N est.*), and N est.* cm under low weed density and 3, 5, 7, 11, 27, and N est.* cm under high weed density, respectively. The predicted DAE at herbicide application time that resulted in a 1%, 2.5%, 5%, 10%, 25%, and 50% yield loss in corn was predicted to be 14, 20, 27, 44, N est.*, and N est.* DAE under low weed density and 5, 7, 11, 17, 25, and 59 DAE under high weed density, respectively. The predicted CHU from planting at herbicide application time that led to a 1%, 2.5%, 5%, 10%, 25%, and 50% yield loss in corn was 468, 636, 821, 1,271, N est.*, and N est.* CHU from planting under low weed density and 207, 283, 385, 551, 972, and 1,748 CHU from planting under high weed density, respectively. The predicted crop stage at herbicide application that led to a 1%, 2.5%, 5%, 10%, 25%, and 50% yield loss in corn was V5, V6, V7, V11, N est.*, and N est.* under low weed density and V1, V2, V3, V4, V8, and V14 under high weed density, respectively. Results indicate that weeds must be controlled before they reach 7 cm in height, prior to 11 d after crop emergence, prior to 385 accumulated CHU from emergence, or prior to the V3 stage under high weed density to avoid greater than 5% yield loss.

AAC McRae soybean

AAC McRae is a high yielding food grade soybean [Glycine max (L.) Merr.] cultivar with yellow hilum, high protein concentration, and acceptable processing quality for foreign and domestic tofu, soymilk, and miso markets. It has excellent soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) and soybean sudden death syndrome (SDS) (Fusarium virguliforme O'Donnell & T. Aoki) resistance. AAC McRae was developed at the Agriculture and Agri-Food Canada (AAFC) Harrow Research and Development Centre (Harrow-RDC), Harrow, Ontario, and is adapted to areas of southwest Ontario with 3100 or more crop heat units and has a relative maturity group of 2.2 (MG 2.2).

AAC Richard soybean

AAC Richard is a food grade soybean [Glycine max (L.) Merr.] cultivar with yellow hilum, high protein concentration, and good processing quality for foreign and domestic soymilk, tofu, and miso markets. It has resistance to soybean cyst nematode (SCN) (Heterodera glycines Ichinohe). AAC Richard was developed at the Agriculture and Agri-Food Canada (AAFC) Harrow Research and Development Centre (Harrow-RDC), Harrow, Ontario, and is adapted to areas of southwest Ontario with 3100 or more crop heat units and has a relative maturity of 2.3 (MG 2.3).

CO477, CO478, CO479, and CO480 inbred lines

CO477, CO478, CO479, and CO480 are mid- to late-season [75–81 d to flowering, crop heat units (CHU) = 1720–1855] corn (Zea mays L.) inbred lines with high stalk sugar levels. The level of sugar in the stalks are very high especially when grown as inbred lines. On average, the inbred lines yield three times more sugar than their testcrosses. These inbred lines are the first to be developed and released for biofuel production, from the corn breeding program of Agriculture and Agri-Food Canada. Additionally, these inbred lines can be used for sugar and (or) silage production. They have moderate to intermediate resistance to common rust, eyespot, northern corn leaf blight and fusarium stalk rot but are susceptible to gibberella ear rot.

Environmental Effects on Soybean (Glycine Max (L.) Merr) Production in Central and South Germany

The cultivation area of soybean (Glycine max (L.) Merr) is increasing in Germany as a way to ensure self-sufficiency through its use as feed and food. However, climatic conditions needed for soybean cultivation are not appropriate in all parts of the country. The objective of this study was to determine the influence of solar radiation, temperature, and precipitation on soybean seed productivity and quality in central and south Germany. A multi-factorial field trial was carried out with three replicates at four locations in 2016 and five locations in 2017, testing 13 soybean varieties from the maturity groups MG 00 and MG 000. Considering all the tested factors, “variety” was highly significant concerning protein content (Ø 41.1% dry matter (DM)) and oil content (Ø 19.1% in DM), but not seed yield (Ø 40.5 dt ha−1).The broad sense heritability of protein content was H2 = 0.80 and of oil content H2 = 0.7. Protein and oil content were significantly negatively correlated (r = −0.82). Seed yield was significantly positively correlated with solar radiation (r = 0.32) and precipitation (r = 0.33), but significantly negatively with Crop Heat Units (CHU) (r = −0.42). Over both experimental years, varieties from maturity group MG 00 were less significantly correlated with the tested environmental factors than varieties from maturity group MG 000. None of the environmental factors tested significantly increased the protein or oil content of soybean. In growing areas with heat periods during ripening, protein content tended to be higher than in cooler areas; in areas with high solar radiation during flowering, protein content tended to be reduced.

AAC Big Ben soybean

AAC Big Ben is a high yielding, soybean cyst nematode resistant food-grade soybean [Glycine max (L.) Merr.] cultivar with yellow hilum and acceptable processing quality for foreign and domestic tofu, soymilk, and miso markets. AAC Big Ben was developed at the Agriculture and Agri-Food Canada (AAFC) Harrow Research and Development Centre (Harrow-RDC), Harrow, ON. AAC Big Ben is adapted to areas of southwestern Ontario with 3300 or more crop heat units and has a relative maturity group of 2.3 (MG 2.3).

AAC Wigle soybean

AAC Wigle is a high yielding, high-protein, large-seeded, soybean cyst nematode resistant food-grade soybean [Glycine max (L.) Merr.] cultivar with yellow hilum and acceptable processing quality for foreign and domestic tofu, soymilk, and miso markets. It was developed at the Agriculture and Agri-Food Canada (AAFC) Harrow Research and Development Centre (Harrow-RDC), Harrow, ON. AAC Wigle is adapted to areas of southwestern Ontario with 3200 or more crop heat units and has a relative maturity of 2.2 (MG 2.2) and protein content of 45.8%.

Registration of HS-182 and HS-183 food-grade soybean [Glycine max (L.) Merr.] germplasm

HS-182 and HS-183 are food-grade soybean lines [Glycine max (L.) Merr.] with distinct seed protein profiles and food processing quality. HS-182 is a 7S β-conglycinin α’ and 11S glycinin A4 null with a high protein concentration of 45.7% and good processing quality. HS-183 is a 7S β-conglycinin α’ and 11S glycinin null with a protein concentration of 42.7% and poor tofu processing quality. They are adapted to areas of southwestern Ontario with 3100 or more crop heat units and have relative maturity groups of 2.5 and 2.4, respectively.

Registration of 11S null food-grade soybean [Glycine max (L.) Merr.] germplasm HS-181

HS-181 is an 11S glycinin null food-grade soybean line [Glycine max (L.) Merr.] with yellow hilum. The absence of 11S subunits would result in a relatively higher concentration of 7S β-conglycinin in soy food. β-conglycinins suppress food intake, which can help to fight obesity. HS-181 is adapted to areas of southwest Ontario with 3100 or more crop heat units and has a relative maturity of 2.5 (MG 2.5).

OAC Bruton soybean

OAC Bruton is an indeterminate large-seeded food-grade soybean [Glycine max (L.) Merr.] cultivar with high yield potential, high seed protein concentration, and resistance to soybean cyst nematode (SCN). OAC Bruton is developed and recommended for soybean growing areas in southwestern Ontario with 2950 or greater crop heat units. OAC Bruton is classified as a maturity group 1 (MG1) cultivar with a relative maturity of 1.8.

OAC Ramsay soybean

OAC Ramsay is an indeterminate large-seeded food-grade soybean [Glycine max (L.) Merr.] cultivar with high yield potential, high seed protein and oil concentrations, and resistance to soybean cyst nematode. OAC Ramsay is developed and recommended for soybean growing areas in southwestern Ontario with 3050 or greater crop heat units and has a relative maturity of 2.2 (MG 2.2).

AAC Argosy navy dry bean

AAC Argosy is a high-yielding navy bean (Phaseolus vulgaris L.) cultivar with an upright, indeterminate bush growth habit, large seed size (23 g 100 seeds−1), and resistance to common bacterial blight and races 1 and 15 of bean common mosaic virus. AAC Argosy is recommended for dry bean growing areas with 2600 or more crop heat units in Ontario, Canada.

Registration of black-seeded douchi food grade soybean Germplasm, HS-172

HS-172 is a black-seeded food-grade soybean line [Glycine max (L.) Merr.] suitable for use to make douchi or fermented, salt-preserved black soybean. It is adapted to the areas of southwest Ontario with 3100 or more crop heat units and has a relative maturity rating of 2.5.

Registration of edamame food grade soybean Germplasm, HS-171

HS-171 is a large-seeded edamame food-grade soybean genotype [Glycine max. (L.) Merr.] with yellow hilum, low oil, and high protein and sucrose concentrations. It is adapted to the areas of southwest Ontario with 3100 or more crop heat units and has a relative maturity rating of 2.6.