Since northern European agricultural practices are likely to go toward systems with lower inputs of N fertilizers, it is desirable to develop cultivars with increased yield potential associated with higher nitrogen use efficiency (NUE). This study determined the extent of variation in NUE‐related parameters, specifying the primary traits contributing to the difference in nitrogen remobilization efficiency (NRE) on four spring cereal crops, two‐ and six‐row barley (Hordeum vulgare L.), oat (Avena sativa L.), and wheat (Triticum aestivum L.). Field experiments were conducted in Finland during 2001, 2002, and 2003 under two N regimes (0 and 90 kg N ha−1). Wheat had relatively high N content at maturity even though NUE was low, whereas oat and barley had higher NUE. A comparison of nitrogen harvest index (NHI) and NRE revealed that both were low for wheat, linking this with high N uptake after anthesis, suggesting that in wheat the proportion of the assimilated N used immediately in the developing grain is greater than in barley and oat. There was no strong N translocation from vegetative parts of the main shoots in wheat, which exhibited higher competition for N between vegetative and reproductive organs. Plant breeders could use these findings to their advantage in breeding spring cereal crops that not only produce high yield but also efficiently use available N in northern growing conditions.

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During 1996-2006 the Ministry of Agriculture and Forestry in Finland, MTT Agrifood Research Finland and the Finnish Geodetic Institute carried out a joint remote sensing satellite research project. It evaluated the applicability of composite multispectral SAR and optical satellite data for cereal yield estimations in the annual crop inventory program. Three Vegetation Indices models (VGI, Infrared polynomial, NDVI and Composite multispectral SAR and NDVI) were validated to estimate cereal yield levels using solely optical and SAR satellite data (Composite Minimum Dataset). The average R 2 for cereal yield (y b ) was 0.627. The averaged composite SAR modeled grain yield level was 3,750 kg/ha (RMSE = 10.3%, 387 kg/ha) for high latitude spring cereals (4,018 kg/ha for spring wheat, 4,037 kg/ha for barley and 3,151 kg/ha for oats).

Cassava (Manihot esculenta Crantz) experiences intermittent water deficit and suffers from potassium (K) deficiency that seriously constrains its yield in the tropics. Currently, the interaction effect between deficit irrigation and K fertigation on growth and yield of cassava is unknown, especially during the early growth phase. Therefore, pot experiments were conducted under controlled greenhouse conditions using cassava cuttings. Treatments initiated at 30 days after planting included three irrigation doses (30%, 60%, 100% pot capacity) and five K (0.01, 1, 4, 16, and 32 mM) concentrations. The plants were harvested 90 days after planting. Decreasing irrigation dose to 30% together with 16 mM K lowered the leaf water potential by 69%, leaf osmotic potential by 41%, photosynthesis by 35%, stomatal conductance by 41%, water usage by 50%, leaf area by 17%, and whole-plant dry mass by 41%, compared with full-irrigated plants. Lowering the K concentration below 16 mM reduced the values further. Notably, growth and yield were decreased the least compared with optimal, when irrigation dose was decreased to 60% together with 16 mM K. The results demonstrate that deficit irrigation strategies could be utilized to develop management practices to improve cassava productivity by means of K fertigation under low moisture conditions.

SUMMARYCultivation of winter turnip rape (Brassica rapa L. ssp. oleifera (DC.) Metzg.) in Finland has been limited because of its reputation as an unreliable crop and its mid-season sowing time of July, when fields are already sown to other crops. An alternative management practice for winter turnip rape is proposed whereby it would be sown as a mixed crop simultaneously with spring cereals. The growth and yield formation of winter turnip rape grown in mixed stands with four different spring cereals was studied in two field experiments conducted in 2009–11. Pure and mixed stands of winter turnip rape and spring cereals were established in May at two different cereal and winter turnip rape stand densities. Subsequent to cereal harvest, one-third of each winter turnip rape plot was harvested for biomass in autumn, before cessation of growth. Three plant stand types, May- and July-sown monocrops and a mixed crop with oat (Avena sativa L.) were sampled for forage analysis. Plant stand densities were monitored from establishment until maturity. Winter turnip rape yield and its quality, including oil content, protein content and thousand seed weight, were determined. Following favourable overwintering conditions, winter turnip rape established with cereals yielded comparably to that of pure stands in terms of both quantity and quality. However, a pure stand of winter turnip rape out-yielded mixed crop stands after unfavourable overwintering conditions. Leaf removal decreased plant survival and seed yield. Establishing winter turnip rape with a cereal in May is an alternative to sowing it as a monocrop in July. A higher seeding rate is needed for under-sown winter turnip rape. Furthermore, autumn-harvested winter turnip rape monocrop forage potentially represents a high-protein supplement for ruminants.