The effects of nitrate supply on the composition (cell numbers, protein and chlorophyll contents) of flag leaves of winter wheat grown with two amounts of N fertilizer and of spring wheat grown in the glasshouse under controlled nitrate supply are described and related to photosynthesis. Nitrogen deficiency decreased the size of leaves, mainly by reducing cell number and, to a smaller extent, by decreasing cell volume. Protein content per unit leaf area, per cell and per unit cell volume was larger with abundant N. Total soluble protein, ribulose tophosphate carboxylase-oxygenase (RuBPc-o) protein and chlorophyll changed in proportion irrespective of nitrogen supply and leaf age. Photosynthesis per unit area of flag leaf and carboxylation efficiency in both winter and spring wheat were proportional to the amount of total soluble protein up to 7-0 g m~2 and to the amount of RuBPc-o protein up to 40 g m~2. However, photosynthesis did not increase in proportion to the amount of total soluble or RuBPc-o protein above these amounts. In young leaves with a high protein content the measured rates of photosynthesis were lower than expected from the amount and activity of RuBPc-o. Carboxylation per unit of RuBPc-o protein, measured in vitro, was slightly greater in N-deficient leaves of winter wheat but not of spring wheat. RuBPc-o activity per unit of RuBPc-o protein was similar in winter and spring wheat leaves and remained approximately constant with age, but increased in leaves showing advanced senescence. RuBPc-o protein from N-deficient leaves migrated faster on polyacrylamide gels than protein from leaves with high N content. Regulation of the rate of photosynthesis in leaves and chloroplasts with a high protein content is discussed. The conductance of the cell to the flux of CO 2 from intercellular spaces to RuBPc-o active sites is calculated, from cell surface areas and CO 2 fluxes, to decrease the CO 2 partial pressure at the active site by less than 0-8 Pa at an internal CO 2 partial pressure of 34 Pa. Thus the decrease in partial pressure of CO 2 is insufficient to account for the inefficiency of RuBPc-o in vivo at high protein contents. Other limitations to the rate of photosynthesis are considered.

Legumes are important in world agriculture, providing biologically fixed nitrogen, breaking cereal disease cycles and contributing locally grown food and feed, including forage. Pea and faba bean were grown by early farmers in Finland, with remains dated to 500 BC. Landraces of pea and faba bean were gradually replaced by better adapted, higher quality materials for food use. While grain legumes have been restricted by their long growing seasons to the south of the country, red, white and alsike clovers are native throughout and have long been used in leys for grazing, hay and silage. Breeding programmes released many cultivars of these crops during the 1900s, particularly pea and red clover. A.I. Virtanen earned the 1945 Nobel Prize in Chemistry for his work on both nitrogen fixation and silage preservation. Use of crop mixtures may appear modern, but farmers used them already in the early 1800s, when oat was used to support pea, and much effort has been devoted to improving the system and establishing its other benefits. Although international cultivars have been easily accessible since Finland's 1995 entry into the European Union, the combination of feed quality and appropriate earliness is still needed, as < 1% of arable land is sown to grain legumes and an increase to 9-10% would allow replacement of imported protein feeds. Climate change will alter the stresses on legume crops, and investment in agronomy, physiology and breeding is needed so that farmers can gain from the many advantages of a legume-supported rotation.

The effect of foliar application of glycinebetaine (50 and 100 mM) on photosynthesis, stomatal conductance, photorespiration and transpiration in tomato cv. Bos 3155 (Lycopersicon esculentum Mill.) and summer turnip rape cv. Kulta (Brassica rapa L. ssp. oleifera) plants subjected to drought and salinity are reported. Glycinebetaine application increased net photosynthesis of stressed plants. This was mostly due to increased stomatal conductance following glycinebetaine application as there were no marked changes in light and CO2 saturated rates of O2 evolution. Moreover, glycinebetaine application resulted in a significant decrease of photorespiration both in drought‐ and salt‐stressed plants.

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High hull content of oat (Avena sativa L.) limits its use as on-farm feed. Dehulling, used in the oat processing industry, can be performed on-farm, to increase nutritive value and energy content. A laboratory model of an impact oat dehuller, similar to a commercial device, was used to study the effects of rotation speed, grain characteristics and moisture content on hullability and groat energy content. Grain of oat cultivar Salo [from official variety trials, MTT Agrifood Research Finland, Jokioinen (60˚49'N), 1996-2000 was assessed for quality prior to dehulling. Impact dehulling rotation speed ranged from 200 to 500 r min -1 at 50 r min -1 intervals, with moisture content of grains ranging from 10% up to 18%. Dehulling improved oat energy content markedly. Hullability was better at higher rotation speeds. 350 r min -1 was determined to be adequate to result in improved quality as no marked additional improvements were demonstrated by increasing rotation speed further. As the proportion of hulless groats increased with higher rotation speeds, nutritional and energy content of groat yield improved consistently. The higher the grain moisture, the higher the proportion of grains retaining hulls. Impact dehulling proved to be a potentially useful method to increase energy content of oat grains on-farm.