Policy makers and farmers in north-west Europe are expressing a growing interest in soybean production. However, cool and wet climatic conditions in this region pose challenges for this crop in terms of reaching maturity and producing sufficient yield and create additional disease pressure from the fungal pathogens Sclerotinia sclerotiorum and Rhizoctonia solani. To increase the chance for successful introduction of this new crop in Belgium and to determine the main issues for local soybean breeding programmes, 14 early maturing varieties were screened over a 2-year-period for their agronomic performance. Based on novel bioassays, susceptibility to S. sclerotiorum and R. solani anastomosis group (AG) 2-2IIIB was evaluated. The varieties tested were able to reach sufficient maturity (average seed moisture content of 19.0%) by the beginning of October. Significant differences were observed in most agronomic characteristics, with seed yield and protein content ranging from 2002 to 2916 kg dry matter/ha and 35.5–43.3%, respectively. Taller varieties ripened later but reached higher protein levels compared with shorter varieties. Tolerance to lodging was correlated with seed and protein yield but was not correlated with plant height. Large seeds corresponded with a high protein content. Susceptibility to S. sclerotiorum reflected significant differences between varieties. In contrast, levels of susceptibility to R. solani AG 2-2IIIB were similar between most varieties, with only the variety Primus showing significantly less disease. The results of the current study hold promise for a successful introduction of soybean cultivation in north-west Europe and areas for further crop improvement have been identified.

The effect of a short cold stress in combination with photoinhibition stress, similar to a low temperature and a high irradiance situation during early morning in the spring time, was examined on four maize cultivars common for Belgium, that differ in early vigour. After 1 h of 2 °C and 500 µmol(photon) m -2 s -1 , quantum efficiency and maximum photosynthesis rate at saturating irradiance decreased on average by 11 and 8 %, respectively. For one cultivar, Magister, the decrease was the largest: by 23 and 10 %, respectively. For this cultivar it was combined with a decrease of the water vapour conductance after the stress. The decrease of F v /F 0 due to the cold/light stress was dependent on the cold tolerance (early vigour) of the cultivars. F v /F 0 changed with -45.5 and -40.2 % for the cultivars Ardiles and Banguy, respectively (cultivars with a less good early vigour) in comparison to -36.3 and -35.9 % for Fjord and Magister, which have a good early vigour. Also the ratio of total chlorophylls/total carotenoids changed in dependence on cold tolerance of the cultivars. For more cold tolerant cultivars, the relative amount of total carotenoids (x+c) was higher, indicating a higher protective state. Both the parameter F v /F 0 and the ratio of total chlorophylls to total carotenoids can be used to differentiate the cold tolerant cultivars from the cold non-tolerant ones. F v /F 0 has the advantage because its resolving power is larger and the measurement is less expensive than determination of the pigment ratio.

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Industrial chicory, Cichorium intybus L., is cultivated for the production of inulin. Most varieties of industrial chicory exhibit rather poor early growth, which limits further yield improvements in their European cultivation area. The poor early growth could be due to suboptimum adaptation of the gene pool to growth at low temperatures, sometimes in combination with high light intensities, which is typical of early-spring mornings. We have used chlorophyll (Chl) a fluorescence to evaluate the response of young plants of the cultivar 'Hera' to low temperatures and high light intensities. Plants were grown at three temperatures: 16°C (reference), 8°C (intermediate), and 4°C (cold stress). Lightresponse measurements were carried out at different light intensities in combination with different measurement temperatures. Parameters that quantify the photosystem II (PSII) operating efficiency (including PSII maximum efficiency and PSII efficiency factor) and nonphotochemical quenching (NPQ) are important to evaluate the stress in terms of severity, the photosynthetics processes affected, and acclimation to lower growth temperatures. The results clearly demonstrate that in young industrial chicory plants the photosynthetic system adapts to lower growth temperatures. However, to fully understand the plant response to the stresses studied and to evaluate the long-term effect of the stress applied on the growth dynamics, the subsequent dark relaxation dynamics should also be investigated.

Bacterial inoculation of soybean seeds to improve biological nitrogen fixation is a well-known practice to achieve higher seed and protein yield with reduced fertilization. The optimal inoculation strategy in temperate regions is unknown because soybeans are rarely cultivated under colder growing conditions. The aim of the present work was to determine the most suitable inoculation strategy for soybean cultivation in Belgium. Field trials were set up with four Bradyrhizobium inoculants (HiStick, Force 48, Biodoz and Optimize) at two locations over 2 years (2014–2015) and compared with a non-inoculated control treatment. In addition, HiStick was tested at three doses and Optimize at two time periods prior to sowing. Under Belgian conditions, all inoculants were effective in establishing rhizobial symbiosis, resulting in increased yield, protein content, protein yield and thousand-grain weight compared with the non-inoculated control. A single dose of HiStick was sufficient to establish symbiosis. Pre-inoculation with Optimize 2 weeks before sowing gave an intermediate performance for most parameters between the non-inoculated control treatment and inoculation with Optimize 24 h prior to sowing. Among the four products tested, Biodoz seemed the best product for inoculation under cool growing conditions. Based on the atpD gene, the bacterial strain of Biodoz showed complete similarity with Bradyrhizobium diazoefficiens, while strains of other products were identified as Bradyrhizobium japonicum. In vitro growing capacity of the Biodoz strain at 8 °C was higher compared with the other strains. Better cold adaptation of the Biodoz strain might be a possible explanation for the better performance of Biodoz in Belgium.