The potential to adapt to climate change varies depending on the crop and is considered low especially for barley (Hordeum vulgare L.) in Europe. Barley is the most widely cultivated crop in Finland, grown in a wide range of climatic and edaphic conditions. Access to a large and diverse assortment of locally well adapted, climate-resilient barley cultivars is the premise for successful cultivation. Barley has plenty of cultivar choices in Finland. However, cultivar switch is "a hidden process," and in this study, we therefore aimed: 1) to increase understanding of farmers' cultivar renewal process; 2) to study how yield and growing time of new cultivars have changed when farmers switched cultivars; and 3) to describe how farms with willingness to change cultivars differ from those reluctant to make a change. The renewal interval of barley cultivars is long: The cultivars grown in 2018 were usually introduced to the Official Variety Trials as early as 2008–2012. The median age difference between replaced and new cultivars was seven years. The probability of switching cultivars was systematically higher on larger farms and farms with a large cereal area. New cultivars were allocated primarily to high-yielding field parcels owned by a farmer. Farmers aspired for an increased yield potential, but this did not necessarily entail a shift to later maturity. We found strong spatial dependency in cultivar renewal if the distance between the neighboring farms was < 5 km. The direction of the change was not only toward new breeds as long as the cultivar was high yielding. When returning to an older cultivar, it was likely that the new breed did not meet the farmer's expectations, or that the growing season was exceptionally challenging.
Naked oat grain, which is free from lemma and palea, has high nutritional quality, but the unprotected grain is prone to mechanical damages caused by combine harvesting. Naked oats were grown for 3 years in southern Finland, at Viikki Experimental Farm, University of Helsinki (60° 13′N) to produce seed material for laboratory tests that evaluated: (1) genotypic differences of naked oat in sensitivity to damage during harvesting at grain moisture varying from c . 10% up to 50%, (2) the effect of mechanical damage on germination and grain vigour, and (3) grain characteristics contributing to susceptibility to reduced grain viability. In 1997, one naked (Rhiannon) and husked oat cultivar (Salo) were harvested, and in 1998–1999 additional four naked cultivars (Bullion, Lisbeth, Neon, SW 95926) were included. One large plot (14 m×10 m) was sown per cultivar. Two sowing times were used. Fully ripened grains were combine harvested on several occasions for each plot to obtain differences in grain moisture at harvest. Simultaneously, panicle samples were collected, dried and threshed by hand (controls). Grain moisture at each sampling and harvesting was monitored. About 3 months after harvesting, germination tests on blotting paper were carried out. Proportions of normally developed seedlings, seedlings lacking either radicle or hypocotyl, damaged coleoptiles, dead grains and lethally fungus-infected grains were recorded from combine harvested and hand threshed samples on different cultivars and harvest moistures. Tests on seedling elongation, seedling emergence through sand (2 cm and 5 cm depth), and ion leakage were applied to evaluate grain vigour. Groat weight, diameter, length, roundness, hardness and protrusion of embryo were determined. Our results indicated that naked cultivars were far more prone to mechanical damages than husked Salo, but differences among naked cultivars in susceptibility occurred. When targeting germination of [ges ] 75%, grain moisture at harvest should not exceed 19–26% depending on cultivar. Abnormal seedlings appeared irrespective of grain moisture at harvest, but the higher the grain moisture, more dead grains were found in harvested grains after storage. Seed vigour did not alter parallel to germination ability. High proportion of small grains in harvested yield and softer groats contributed to decreased sensitivity to mechanical damages.
Plant growth regulators (PGRs) alter tiller growth in cereals. This response may be dependent on daylength (DL). Standard height (HE) and dwarf oat cultivars were grown at 14‐ and 18‐h DLs. Foliage was sprayed with chlormequat chloride (CCC) and ethephon at early growth stages to evaluate PGR effects on the growth of the main shoot and tillers. Two successive experiments with 10 replicates were arranged in two growth chambers (14‐h and 18‐h DL) at the University of Minnesota. Preanthesis main shoot and tiller HEs and dry weights (DWs) were measured. In Exp. 1, the numbers of leaves and green leaves were counted. Relative growth rate (RGR), relative elongation rate (RER), and shoot DW:HE ratio were measured. Plant growth regulators retarded growth of the main shoot in conventional oat cultivars without stimulating growth of T1 and T2 tillers. Response of the dwarf cultivar to PGRs was modest. Only ethephon enhanced T1 tiller growth at 18‐h DL. However, PGR‐treated plants had up to five more green leaves per plant at preanthesis due to stimulated leaf emergence on T3 and T4 tillers especially at the 18‐h DL. In Exp. 1, PGR treatments reduced the DW to HE ratio, that is, shortened rather than strengthened the stem. In Exp. 2, measurements were made more frequently and ethephon first increased this ratio followed by a decrease. Thus, even though long‐day conditions somewhat enhanced DW accumulation and stem elongation, few marked differences in oat response to PGR treatments were noted when comparing short‐ and long‐day conditions.
Abstract Drought occurring at critical growth and developmental stages in cereals affects productivity by reducing biomass accumulation, grain set, and grain yield and quality. Maize (cv. SR‐73), sorghum (cv. Trump), and wheat (cv. Spear) were established in drought‐prone field conditions in Perth, Western Australia, in l994. The plants were then subjected to optimal and suboptimal supplementary watering regimes at growth stages that were sensitive to water availability. Glycinebetaine in aqueous solution was applied to leaves at three rates (2, 4 and 6 kg ha −1 and a control) to establish whether its application could ameliorate the effects of drought on the yield of the crops. Above‐ground biomass production was measured at the beginning and at termination of the watering regimes. Leaf tissue glycinebetaine concentrations were determined 1 and 3 weeks after application. At physiological maturity, grains from the crops were harvested and grain yield, number of grains m −2 and single grain weight were recorded. Drought significantly reduced above‐ground biomass production in maize (P = 0.047), but not in sorghum and wheat. Grain yield of maize, number of grains m −2 of maize and sorghum, and single grain weight of sorghum were significantly depressed by drought. Foliar application of aqueous glycinebetaine marginally enhanced biomass production in the three crops and significantly increased grain yield of maize (P = 0.001) and sorghum (P = 0.003). It also resulted in more grains m −2 of maize, sorghum and wheat (P = 0.001, 0.001 and 0.003, respectively), with interactions between water and glycinebetaine treatments for sorghum and wheat (P = 0.001 and 0.001. respectively). Residual tissue glycinebetaine levels remained high 3 weeks after application to the crops. The positive effects of glycinebetaine treatment appear to be linked to its physiological role as a plant osmoticum that improves drought tolerance. The results of these studies suggest that foliar application of glycinebetaine may be used to improve drought tolerance and economic yield of maize and sorghum, but not of wheat. Increased grain yield was associated with more grains m −2 rather than greater single grain weight.
Abstract Increases in atmospheric carbon dioxide (CO 2 ) concentration have stimulated interest in the response of agricultural crops to elevated levels of CO 2 . Several studies have addressed the response of C 3 cereals to CO 2 , but the interactive effect of nutrient supply and CO 2 on apical development and spikelet set and survival has not been investigated thoroughly. Hence, an experiment was conducted in the greenhouse to evaluate the effect of high (700 μmol CO 2 mol −1 air) and low (400 μmol mol −1 ) levels of atmospheric CO 2 on apical development, spikelet set and abortion, and pre‐ and post‐anthesis growth in spring barley (Hordeum vulgare L.) grown under high N (0.3 g N pot −1 before sowing −1–0.11 g N pot −1 week −1 ) and low N (0.3 g N pot −1 ) regimes. The plants were grown in 5 L pots. Development of spike was hastened due to CO 2 enrichment, and the C+ plants pollinated few days earlier than the C— plants. Carbon dioxide enrichment had no effect on date of ripening. Development of spike slowed following application of extra N, and plants pollinated 10 days later and matured 2 weeks later when compared with plants under low N. Carbon dioxide enrichment did not affect the number of spikelets at anthesis. Excess N decreased spikelet abortion and the increased maximum number of spikelets under both [CO 2 ]. Barley plants did not tiller when grown in low [CO 2 ] and low N. Increased endogenous IAA concentration in those plants, recorded three days before tillers appeared in other treatments, may have contributed to this. Carbon dioxide enrichment increased the C concentration of plants, but decreased the N concentration under high N regime. Both the C and N concentration of plants were increased under high N regime. Carbon dioxide enrichment increased the total dry matter of mature plants by 9 % under high N regime and by 21 % under low N regime. Under high [CO 2 ] increased kernel number on tiller spikes, and increased kernel weight both on main stem and on tiller spikes resulted in a 23 % increase in kernel yield under low N regime and 76 % increase in kernel yield under high N regime. The rate of N application influenced growth and yield components to a greater extent than CO 2 enrichment. At maturity, plant dry matter, kernel weight, the number of kernels per spike, and the number of spikes per plant were higher under high N regime than under low N regime. Long days (16 h), low light intensity (280 μmol m −2 s −1 ), and at constant temperature of 20 °C high [CO 2 ] increased kernel weight and the number of kernels on tiller spikes under high and low N application rate, but did not increase the number of kernels on main stem spike, or the number of tillers or tiller spikes per plant.
