Early-Season Mapping of Winter Crops Using Sentinel-2 Optical Imagery

Sentinel-2 imagery is an unprecedented data source with high spatial, spectral and temporal resolution in addition to free access. The objective of this paper was to evaluate the potential of using Sentinel-2 data to map winter crops in the early growth stage. Analysis of three winter crop types—winter garlic, winter canola and winter wheat—was carried out in two agricultural regions of China. We analysed the spectral characteristics and vegetation index profiles of these crops in the early growth stage and other land cover types based on Sentinel-2 images. A decision tree classification model was built to distinguish the crops based on these data. The results demonstrate that winter garlic and winter wheat can be distinguished four months before harvest, while winter canola can be distinguished two months before harvest. The overall classification accuracy was 96.62% with a kappa coefficient of 0.95. Therefore, Sentinel-2 images can be used to accurately identify these winter crops in the early growth stage, making them an important data source in the field of agricultural remote sensing.

Forage Yield and Quality of Winter Canola–Pea Mixed Cropping System

Forage crop–dairy farming is an important agro-industry across the world. This system is intensive with high-input forage crops. In the United States (US) Southern Great Plains, the system is based primarily on high-input annual grass-type crops in monocropping approaches and requires diverse low-input broadleaf crops for strengthening its sustainability. Winter canola (Brassica napus L.) and pea (Pisum sativum L.) have the potential to provide forage crop diversity options with high forage yields of high quality. Winter canola and pea in mono- and mixed-cropping approaches at seeding ratios of canola/pea at 0:100, 25:75, 50:50, 75:25, and 100:0 were studied for yield and quality in 2015 and 2016 in Clovis, New Mexico (NM). Averaged over years, canola–pea at 75:25 and 50:50 seeding ratios produced similar biomass forage yield but higher than mono-pea by 43% and canola–pea at 25:75 and mono-canola cropping by 8%. The land equivalent ratio of all mixed-cropping treatments exceeded 1.0, with canola–pea at the 50:50 seeding ratio recording a land equivalent ratio of 1.15, indicating that mixed-cropping systems are better users of land resources. Total digestible nutrients and relative feed value were higher in canola–pea mixed cropping than in mono-canola and mono-pea cropping. Canola–pea mixed cropping achieved high yields (13.3 to 14.7 Mg·ha−1) with improved forage quality, as well as improved crop and land productivity, with the potential to improve mechanical harvestability of vining pea, and strengthen the diversity and sustainability of forage crop–dairy farming in the Southern Great Plains under limited irrigation input of ~300 mm.

Genome-Wide Association Mapping of Freezing Tolerance Loci in Canola (Brassica napus L.)

Winter canola generally produces greater yields than spring canola. However, its range is limited due to its inability to withstand the harsh winter conditions that occur in many northern regions of the U.S.A. To identify loci associated with freezing tolerance in canola, we conducted a genome-wide association study (GWAS) using a genotyped diversity panel containing 399 accessions consisting primarily of winter canola. One-month-old greenhouse grown plants were subsequently cold-acclimated for two months in an environmental growth chamber prior to phenotyping for freezing survival using a visual damage scale and chlorophyll fluorescence (Fv/Fo). There was reasonable correlation observed between visual damage and chlorophyll fluorescence ratings among the top associated loci; the results indicated that some loci contributed to both freezing damage/tolerance and photosynthetic efficiency. The resulting numerical values for phenotypes were used for association analyses with the identified SNPs. Thirteen significant markers were identified on nine chromosomes for the phenotypes scored, with several showing significance for multiple phenotypes. Twenty-five candidate genes were identified as previously associated with freezing tolerance, photosynthesis, or cold-responsive in canola or Arabidopsis.

Effect of seeding date on winter canola (Bassica napus L.) yield and oil quality in southern Ontario

Winter canola or winter oilseed rape (Brassica napus L.) is not commonly grown in Canada. While winter oilseed rape is the dominant growth form in Europe, Canadian canola production is dominated by spring types in western Canada. Research conducted in the 1980s indicated that the environmental conditions in southern Ontario are well suited to the production of winter canola. Since then, however, interest in the crop has ebbed and little to no research has been conducted on the agronomic issues that potentially limit its adoption in the province. The objective of this research was to identify an optimal seeding date for winter canola in southern Ontario. Three winter canola hybrids were evaluated across five seeding dates ranging from early September to late October. Results established the first two weeks of September as the optimal seeding period for winter canola in southern Ontario. Seeding winter canola during this period, such that greater than 600 GDD could be accumulated before the first fall frost, not only reduced winterkill to approximately 20% but also maximized yield potential and ensured optimal oil quality. Winter canola showed great potential for production in southern Ontario and its addition to current crop rotations would diversify and enhance crop production practices in this portion of the province.