La germination et la croissance hétérotrophe sont des phases clés de l'établissement des plantes. Ils sont sous contrôle génétique et affectés par la température. L'objectif de cette thèse est d'analyser la variabilité inter et intra-spécifique de cinq espèces prairiales dans leurs réponses à la température pendant la germination et la croissance hétérotrophe. Trente-deux populations de Lolium perenne, Festuca arundinacea, Dactylis glomerata, Medicago sativa, et Onobrychis viciifolia ont été évalués sous huit températures constantes entre 5 et 40°C.La nouveauté de ce travail vient de la large gamme de températures et le nombre de populations évaluées. Il a été observé que, au sein des espèces, la réaction des populations à la température indique une forte variabilité et des différences significatives. La germination n'a été pas observée à 40°C pour l'une des 23 graminées, l'O. viciifolia germé peu tandis que les variétés de M. sativa ont été peu affectées. La croissance hétérotrophe des 32 populations a été affectée par la température. La croissance des axes fortement fiable ou nulle à 40°C. Les courbes de réponse du taux de croissance maximale de l'axe sont asymétriques en forme de cloche.Des interactions significatives entre la température et la population ont été détectées pour la germination et la croissance hétérotrophe. La germination des populations des sites froids est renforcée par des températures plus chaudes et limité par les plus froids et vice-versa pour les populations chaudes adaptées. / Germination and heterotrophic growth are key phases for plant establishment. They are under genetic control and affected by temperature. The objective of this thesis was to analyse the inter- and intra-specific variability of five pasture species in their responses to temperature during germination and heterotrophic growth.Thirty two populations of Lolium perenne, Festuca arundinacea, Dactylis glomerata, Medicago sativa, and Onobrychis viciifolia were evaluated under eight constant temperatures between 5 and 40°C.The novelty of this work comes from the wide range of temperatures and the number of populations evaluated. It was observed that, within species, the response of populations to temperature shows high variability and significant differences. No germination was observed at 40°C for any of the 23 grasses, O. viciifolia germinated poorly while M. sativa varieties were little affected. Heterotrophic growth of the 32 populations was affected by temperature. The growths of the axes were negligible or lethal at 40°C. Response curves of maximum growth rate of the axis were asymmetric bell-shaped.Significant interactions between temperature and population were detected for germination and heterotrophic growth. Germination of populations from cold sites is enhanced by warmer temperatures and limited by colder ones and vice versa for warm-adapted populations. This study demonstrates that genetic variability does exist within the five studied species. This variability could be exploited to breed new varieties adapted to the future climate.

In the future, the cultivation of algae for food may become increasingly important in Sweden. But this area is still new in Europe and most of the harvest today comes from wild stocks. In Sweden, cultivation is only available on the west coast, but research is underway to see if it is possible to start cultivating macroalgae in the Baltic Sea as well. The Baltic Sea has completely different biological conditions than the west coast, and one of the challenges is the low salinity, which limits the species that can live in the Baltic Sea. This is something that the Marine Center in Simrishamn is also researching in the project Tångkusten, of which this study is a part of. The purpose of this study is to use a literature study to compile available knowledge about which algae that has the potential to be cultivated in the future and what the life cycles of these algae look like. An inventory of the macroalgae found locally in Hanöbukten was also carried out. Based on this information, possible cultivation methods and the advantages of each species are discussed, but also the challenges that may arise.  The results showed that the most abundant species were filamentous brown algae, bladder wrack and saw wrack . The species deemed most cultivable are gut weed and sea lettuce. Clawed fork weed, bladder wrack and saw wrack are also considered to have some cultivation potential. Among the biggest challenges are the growth of epiphytic algae and finding a suitable site for cultivation. / Projektet Tångkusten på Marint centrum i Simrishamn

This research examined the mechanisms by which temperature, water availability and nitrogen (N) affect the dry matter (DM) yield potential of cocksfoot (Dactylis glomerata L.) dominant pastures. The experiment was a split plot design with main plots of fully irrigated (I) or dryland (D), sub-plots of N fertiliser at 800 kg N/ha in 2003/04; and 1600 kg N/ha in 2004/05 (+N) or 0 kg N/ha (-N). The potential environmental yield of an established 8 year old cocksfoot dominant pasture was 21.9 t DM/ha/y from I+N pastures compared with 9.8 t DM/ha by I-N pastures and 15.1 t DM/ha/y by D+N pastures. The lowest yields were from dryland pastures with no N which produced 7.5 t DM/ha/y in 2003/03 and 5.0 t DM/ha/y in 2004/05. The effect of seasonal temperatures on the DM production, when periods of water stress were excluded, was quantified using thermal time accumulated above a base temperature of 3°C as 7.0 kg DM/°Cd/ha for N fertilised pastures and 3.3 kg DM/°Cd/ha for pastures with no N. The 2.5 t DM/ha difference in yields of D-N pastures in 2003/04 and 2004/05 was the result of the duration, extent and timing of the water stress period. In both years the critical limiting deficit (DL) was calculated as 78 mm from the soil moisture deficit in the 0-0.8 m soil layers. Beyond DL yield decreased at a rate of 1.45%/mm in +N and –N pastures, relative to fully irrigated control pastures. Yields of D+N and D-N pastures were similar during periods of water stress with 0.4±0.1 t/DM/ha produced during the rotation ending 30/12/2003. This was less than from either the I-N (1.2 t DM/ha) or I+N (3.5 t DM/ha) pastures due to the reduction in the amount of photosynthetically active radiation intercepted by the canopies of the dryland pastures. However, in the rotation ending 2/5/2004, after autumn rain alleviated drought conditions, yield of the D+N pasture was 2.1 t DM/ha compared with 1.7 t DM/ha by I+N pastures. The effect of N on yield was described using a nutrition index which showed that as DM yield increased N% in the herbage declined. This is a function of the ratio between metabolic and structural N requirements rather than caused by ontogeny alone. Specific leaf N was determined at two harvests and appeared constant at a given point in time (1.0-1.6 g N/m² leaf). In contrast, specific pseudostem N increased from 0.8-1.0 g N/m² pseudostem at an NNI of 0.4 in –N pastures to 2.6-3.0 g N/m² pseudostem at an NNI of 1.2 in the +N pastures. Differences between the yields of +N and –N pastures were caused by differences in radiation use efficiency (RUE) as determined by the linear relationship (R²=0.76) between RUE and the nitrogen nutrition index (NNI). In this thesis, empirical relationships for the effects of temperature, water availability and N were derived and the physiological mechanisms which underlie these descriptions were identified. These relationships provide clear and simple explanations of the effects of environmental variables on the productivity of cocksfoot based pastures which will enhance understanding of the benefits and limitations of cocksfoot, particularly in dryland farming systems.

The vegetative and reproductive development of balansa clover (Trifolium michelianum Savi.) were quantified in relation to the environmental drivers of each phenophase in field and controlled environments. In a grazed experiment over 6 years, balansa clover sown with cocksfoot (Dactylis glomerata) contributed 1.6 t DM/ha/year, or ~20% of the total DM production. However, grazing management for increased seed production during flowering in the establishment year strongly influenced balansa clover regeneration. The earliest closed plot (September) averaged between 2.2 and 4.3 t DM/ha/year of balansa clover across all six years. In an incubator, balansa clover required 29°Cd for germination with an optimum temperature of 14°C and a maximum of 40°C. The base temperature for germination was 0°C. A field experiment determined that 38°Cd were required for emergence with an optimum soil temperature (Topt) of 8.5°C. The time from emergence until the first leaf appeared, the phyllochron and timing of axillary leaf appearance were compared with perennial ryegrass (Lolium perenne) and white clover (Trifolium repens L.). The rate of each was found to increase linearly with temperature. The balansa clover cultivar ‘Frontier’ required 97°Cd from sowing for the first leaf to appear, had a phyllochron of 47°Cd and secondary leaves appeared after 490°Cd. For each vegetative stage, the base temperature was 2.5°C. The timing of flower appearance depended on the quantity and direction of change of the photoperiod at emergence. A balansa clover plant, cv. ‘Bolta’, which emerged on 1 December into an increasing photoperiod of 15.6 hours flowered after 574°Cd (Tbase = 2.5°Cd) or 58 days after emergence. In contrast, if the plant emerged on 16 January into a similar but decreasing photoperiod it took 1503°Cd or 227 days to flower. This length of time became progressively shorter until remaining constant after the shortest day. In contrast, ‘Frontier’ took a constant 390 and 690 °Cd in increasing and decreasing photoperiods, respectively. The time which an individual inflorescence took from pollination until seeds were physiologically mature was 250 °Cd for both ‘Bolta’ and ‘Frontier’. The re-establishment of balansa clover each year relied on a large seed set (>1000 kg/ha) in the establishment year. The continued survival of balansa clover would then depend on a similar seeding event within a 4-5 year period to maintain the seed bank. Management considerations for balansa clover persistence and survival are discussed.

Despite the importance of a high white clover (Trifolium repens) content in temperate pastoral systems in terms of livestock performance and nitrogen fixation, the proportion of white clover in grass-clover pastures is often low (<20%). This thesis examined in two experiments whether the white clover content of pastures could be improved by sowing white clover with alternative grass species to diploid perennial ryegrass (Lolium perenne L.). In a pasture experiment, DM production, pasture composition and morphology of grass-clover mixtures was measured over the establishment year (January 2007 to January 2008) where white clover was sown in fine mixtures with diploid perennial ryegrass, tetraploid perennial ryegrass, timothy (Phleum pratense L.) and cocksfoot (Dactylis glomerata L.). Pastures were irrigated and rotationally grazed with on-off grazing with Coopworth ewe hoggets. Total annual DM production of pasture was more than 20% higher in tetraploid (12521 kg DM ha⁻¹) and diploid (11733 kg DM ha⁻¹) perennial ryegrass than timothy (9751 kg DM ha⁻¹) and cocksfoot (9654 kg DM ha⁻¹). However, timothy (5936 kg DM ha⁻¹) and cocksfoot (5311 kg DM ha⁻¹) had more than four times higher white clover annual DM production than tetraploid (1310 kg DM ha⁻¹) and diploid (818 kg DM ha⁻¹) ryegrass. Pasture growth rate at the first three harvests in autumn was significantly greater in tetraploid and diploid ryegrass than timothy and cocksfoot. Timothy and cocksfoot had a higher proportion of white clover than tetraploid and diploid perennial ryegrass throughout the entire year. This was due to more and larger white clover plants in timothy and cocksfoot plots. In a grazing preference experiment, the partial preference of sheep for white clover offered in combination with the same grass species as in the pasture experiment was measured in five grazing tests in May, September, October, November and December 2007. Pastures were sown in January 2007. Paired plots (grass and clover both 4.2 m x 10 m) were grazed by three Coopworth ewe hoggets between 9am and 5pm, and preference was recorded by decline in pasture mass and visual scan sampling for grazing time. Grazing preference for clover was generally low throughout these tests (e.g. average apparent DM intake from clover = 47%; average grazing time from clover = 44%). Several explanations are proposed for this low preference including a high N content and intake rate of the grass relative to the clover. No significant differences were found among the grass treatments in total grass grazing time, total clover grazing time, ruminating time, the proportion of grazing time on clover, selective coefficient for clover and DM intake percentage from clover at any date. There was no significant change in overall sward surface height (SSH) decline among grass treatments throughout all the tests except December 2007 when the overall SSH decline for cocksfoot was significantly lower than the other species. The study indicated that the rapid growth rate of perennial ryegrass in the early phase of pasture establishment, rather than differences in partial preference, was the key factor limiting white clover content in the mixed swards relative to cocksfoot and timothy pastures. It is concluded that high clover-containing pastures capable of delivering high per head performance can be established through the use of slow establishing pasture species such as timothy and cocksfoot.

This study consisted of two sheep grazed dryland pasture experiments. Experiment l compared sheep production from 3-year-old cocksfoot based pastures grown in combination with white, Caucasian, subterranean or balansa clover with a ryegrass-white clover pasture and a pure lucerne forage. Sheep liveweight gain per head from each pasture treatment and the pure lucerne stand was recorded in the 2006/07 and 2007/08 seasons. The cocksfoot-subterranean clover pasture provided equal (381 kg LW/ha in 2006) or higher (476 kg LW/ha in 2007) animal production in spring and gave the highest total animal production (646 kg LW/ha) averaged across years of the five grass based pastures. However, total annual liveweight production from lucerne was higher than any grass based pasture mainly due to superior animal production during summer when lucerne provided 42-85% higher animal production than any of the grass based pastures. In Experiment 2, the effect of stocking rate (8.3 (low) and 13.9 (high) ewes + twin lambs/ha) and time of closing in spring on lamb liveweight gain, pasture production and subterranean clover seedling populations was monitored over 2 years for a dryland cocksfoot-subterranean clover and ryegrass-subterranean clover pasture in Canterbury. In both years, twin lambs grew faster (g/head/d) in spring at low (327; 385) than high (253; 285) stocking rate but total liveweight gain/ha (kg/ha/d) was greater at high (7.26; 7.91) than low (5.43; 6.38) stocking rate. Ewes also gained 0.5 and 1.5 kg/head at the low stocking rate in 2006 and 2007 respectively but lost 0.2 kg/head in 2006 and gained 0.3 kg/head at high stocking rate in 2007. Mean subterranean clover seedling populations (per m²) measured in autumn after grazing treatments in the first spring were similar at both low (2850) and high (2500) stocking rate but declined with later closing dates in spring (3850, 2950, 2100 and 1700 at 2, 4, 6, 8 weeks after first visible flower). Seedling populations measured in autumn after grazing treatments in the second spring were also unaffected by stocking rate (low 1290, high 1190) but declined with later closing dates in spring (1470, 1320 and 940 at 3, 5 and 8 weeks after first flowering, respectively). The effect of stocking rate and closing dates in spring on pasture and clover production in the following autumn was similar to the effects on seedling numbers in both years. However, clover production in the following spring was unaffected by stocking rate or closing date in the previous year at the relatively high seedling populations generated by the treatments. This was presumably due to runner growth compensating for lower plant populations in pastures that were closed later in spring. Subterranean clover runner growth in spring may not compensate in a similar manner if seedling numbers in autumn fall below 500/m². Mean annual dry matter production from cocksfoot and ryegrass pastures grown with and without annual clovers pasture production ranged from 6.4 to 12.4 t DM/ha/y but stocking rate (8.3 vs. 13.9 ewes/ha) during spring did not affect annual pasture production. Pastures overdrilled with annual clovers yielded 23-45% more dry matter production than pastures grown without annual clovers. The study confirms the important role of subterranean clover in improving pasture production and liveweight gains of sheep in dryland cocksfoot and ryegrass pastures. Lowering stocking rate from 13.9 to 8.3 ewes/ha was a less effective method of increasing seed production of subterranean clover in dryland pastures although it did lead to increased liveweight gain per head.

The annual and seasonal water use efficiency of six pasture combinations were calculated from the ‘MaxClover’ Grazing Experiment at Lincoln University. Pastures have been established for six years and are grazed by best management practices for each combination. Measurements for this study are from individual plots of four replicates of ryegrass (RG)/white clover (Wc), cocksfoot (CF)/Wc; CF/balansa (Bal) clover; CF/Caucasian (Cc) clover; CF/subterranean (Sub) clover or lucerne. Water extraction measurements showed soils for all dryland pastures had a similar plant available water content of 280±19.8 mm. Dry matter measurements of yield, botanical composition and herbage quality were assessed from 1 July 2008 until 30 June 2009. Lucerne had the highest annual yield of 14260 kg DM/ha/y followed by the CF/Sub at 9390 kg DM/ha/y and the other grass based pastures at ≤ 6900 kg DM/ha/y. All pastures used about 670±24.4 mm/y of water for growth. Lucerne had the highest annual water use efficiency (WUE) of 21 kg DM/ha/mm/y of water used (total yield/total WU). The WUE of CF/Sub was the second highest at 15 kg DM/ha/mm/y, and the lowest was CF/Wc at 9 kg DM/ha/mm/y. The CF/Sub pastures had the highest total legume content of all grass based pastures at 21% and as a consequence had the highest annual nitrogen yield of 190 kg N/ha. This was lower than the monoculture of lucerne (470 kg N/ha). Ryegrass/white clover had the highest total weed component in all pastures of 61%. For dryland farmers spring is vital for animal production when soil temperatures are rising and moisture levels are high. The water use efficiency at this time is important to maximize pasture production. In spring lucerne produced 8730 kg DM/ha, which was the highest dry matter yield of all pastures. The CF/Sub produced the second highest yield of 6100 kg/DM/ha. When calculated against thermal time, CF/Sub grew 5.9 kg DM/ºCd compared with lucerne at 4.9 kg DM/ºCd. The higher DM yield from lucerne was from an extra 400 ºCd of growth. The highest seasonal WUE of all pastures occurred in the spring growing period. Linear regressions forced through the origin, showed lucerne (1/7/08-4/12/08) had a WUE of 30 kg DM/ha/mm (R2=0.98). Of the grass based pastures, CF/Sub produced 18 kg DM/ha/mm (R2=0.98) from 1/7 to 10/11/08 from 270 mm of water used. The lowest spring WUE was 13.5 kg DM/ha/mm by CF/Bal pastures which was comparable to the 14.3±1.42 kg DM/ha/mm WUE of CF/Wc, CF/Cc and RG/Wc pastures. During the spring, CF/Sub clover had the highest spring legume component of the grass based pastures at 42% and produced 120 kg N/ha. This was lower than the 288 kg N/ha from the monoculture of lucerne. Sub clover was the most successful clover which persisted with the cocksfoot. Based on the results from this study dryland farmers should be encouraged to maximize the potential of lucerne on farm, use cocksfoot as the main grass species for persistence, rather than perennial ryegrass, and use subterranean clover as the main legume species in cocksfoot based pastures. By increasing the proportion of legume grown the water use efficiency of a pasture can be improved. When pastures are nitrogen deficient the use of inorganic nitrogen may also improve pasture yields particularly in spring.