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The Grasslands II perennial ryegrass (Lolium perenne L.) mapping population comprising F1 progeny with the two parents (one plant each from the cultivars Samson and Impact) (Crush et al., 2007) was used to detect putative quantitative trait loci (QTL) for leaf Rubisco turnover and herbage yield traits. Rubisco turnover was described by three mathematical parameters: d (maximum Rubisco content), g (time of d) and f (a measure of curve width). All three parameters exhibited continuous variation among the F1 progeny. Sixteen QTL were detected, seven for Rubisco turnover and nine for herbage yield traits. Support interval overlap on linkage group (LG) 1 and close location on LG2 for plant dry weight (DW) QTL in this study and in a previous analysis (Sartie, 2007) of the same mapping population suggests DW QTL stability across environments. Some QTL identified by Sartie (2007) were not re-confirmed in this study, but new QTL were identified. This suggests genotype x environment interaction generated by variable expression of genes in different environments. Clusters of QTL with overlapping support intervals were found on LG2 and LG5. The cluster on LG2 included QTL for herbage yield traits leaf lamina length (LL), tiller number (TN), productivity index (PI) and DW. The cluster on LG5 included QTL for DW, PI, TN, and d. These two regions offer potential for plant breeding applications. Apart from the QTL for d on LG5, there was no co-location of Rubisco turnover and herbage yield QTL. However, principal component analysis indicated plants with lower d tended to have higher DW; thus Rubisco turnover effects on plant productivity may relate to energy cost of Rubisco synthesis rather than photosynthetic capacity. DW was generally unrelated to f and g; therefore, hypothesised nitrogen use inefficiencies arising from premature Rubisco degradation, or retention of Rubisco at leaf senescence, were not confirmed. LG5 and LG7 on which QTL for d were located have conserved syntenic regions with rice chromosomes 8 and 9 where QTL for Rubisco content at different stages during heading were mapped by Ishimaru et al (2001a).

Les hydrocarbures aromatiques polycycliques (HAP) sont des polluants organiques persistants potentiellement mutagènes et cancérigènes. Leur transfert de l'atmosphère vers les écosystèmes, notamment vers les plantes, conditionne leur entrée dans les chaines alimentaires mais les modalités de ce transfert restent encore mal connues. L'objectif de ce travail était donc de caractériser le transfert et d'identifier les effets biologiques des HAP atmosphériques sur un système sol-plante-microorganismes symbiotiques.Un dispositif expérimental a été conçu afin de recréer en laboratoire une pollution atmosphérique par les HAP avec comme HAP modèle le phénanthrène (PHE). Le dispositif a fait l'objet d'une validation et d'une calibration élaborée de manière originale par une double approche mêlant l'expérimental à la simulation mathématique. Les niveaux d'exposition en polluant (150 µg m-3), contrôlés par des échantillonneurs passifs, se sont avérés pertinents par rapport aux conditions in situ. Ce dispositif a donc été utilisé pour exposer durant un mois des microsystèmes sol-plante-microorganismes au PHE par voie atmosphérique.Les différentes études ont mis en évidence un transfert du PHE depuis l'atmosphère vers tous les compartiments du microsystème, avec une accumulation majeure vers les feuilles de trèfle ou de ray-grass (respectivement 170 et 70 µg g־ ¹MS) et un transfert phloémien vers les racines est suggéré. Chez le trèfle, la mycorhization n'a pas été affectée, tandis que le nombre de nodules actifs a diminué de manière significative. Contrairement aux racines, la biomasse aérienne du trèfle a été significativement affectée (environ - 25%) par l'exposition au PHE atmosphérique, suggérant un impact sur le métabolisme carboné de la plante. Une expérience de marquage des trèfles au ¹³C-CO2 a effectivement montré un impact négatif du PHE atmosphérique sur la croissance, l'allocation de biomasse et l'allocation carbonée. Pour conclure, ces études ont permis non seulement de caractériser les effets biologiques et physiologiques des HAP atmosphériques sur les végétaux mais également de proposer l'utilisation du potentiel mycorhizien comme indicateur de pollution atmosphérique par les HAP.

Soil contamination with heavy metals is a problem of worldwide concern that is still unsolved. The analysis of the current methods of soil cleaning from heavy metals leads to conclusions that phytoremediation, i.e. soil decontamination by using plants, is one of the best methods. Although this method has not received a wide application yet and possibilities of its application are still being analysed, it is one of the most prospective soil cleaning methods due to low cost and a rather efficient cleaning of the upper surface of soil. Three kinds of Poaceae f. Species – Lolium perenne L., Poa pratensis L. and Festuca pratensis Huds. – have been chosen in this work for decontaminating soil from heavy metals. These plants were grown under artificial laboratory conditions in soil which was once and periodically contaminated with heavy metals. It was established that it is the Lolium perenne L. that most efficiently removes heavy metals and cleans soil. The results of experiments show that the selected grassy plants (perennial ryegrass, meadow-grass and fescue-grass) efficiently clean soil from heavy metals (copper, lead, manganese, zinc, nickel and chromium) when soil contains both low (0.5–120 mg/kg) and high (up to 6,850 mg/kg) concentrations of these metals. Since the perennial ryegrass absorbs the highest amount of heavy metals, the highest efficiency of soil cleaning is achieved using this plant, therefore, 80 % of the mixture of grassy plants was formed of the perennial... [to full text] / Dirvožemio tarša sunkiaisiais metalais visame pasaulyje aktuali problema iki šiol neturinti universalaus sprendimo. Išanalizavus šiuo metu dirvožemio valymui nuo sunkiųjų metalų naudojamus metodus, galima daryti išvadą, kad vienas iš tinkamiausių metodų yra fitoremediacija, t. y. dirvožemio valymas nuo teršalų panaudojant augalus. Šis metodas dar nėra plačiai taikomas ir jo taikymo galimybės dar tik tiriamos tačiau, tai vienas iš perspektyviausių dirvožemio valymo metodų dėl sąlyginai mažos kainos ir pakankamai efektyvaus paviršinio dirvožemio sluoksnio išvalymo. Atliktų eksperimentinių tyrimų rezultatai parodė, kad pasirinkta žolinė augalija – daugiametė svidrė, pievinė miglė ir tikrasis eraičinas efektyviai valo dirvožemį nuo sunkiųjų metalų (vario, švino, mangano, cinko, nikelio, chromo) tiek esant mažoms (0,5–120 mg/kg), tiek didelėms (iki 6850 mg/kg) jų koncentracijoms dirvožemyje. Kadangi daugiausiai sunkiųjų metalų iš dirvožemio sorbuoja svidrė, tai dirvožemio valymo efektyvumas naudojant šią žolinės augalijos rūšį yra efektyviausias ir sudarant žolinės augalijos mišinį 80  sudarė svidrė ir po 10  eraičinas bei miglė. Eksperimentų metu tirta, kaip sunkiųjų metalų mišinio koncentracijos kenkia hidrobiontams ir nustatyta, kad didinat sunkiųjų metalų mišinio koncentracijas (iki 0,198–5,12 g/l) jos tampa letalinėmis vaivorykštiniam upėtakiui, tuo pačiu ir kitiems vandens gyvūnams.Pagal tyrimų su vaivorykštiniais upėtakiais rezultatus nustatyta, kad stebimų... [toliau žr. visą tekstą]

Dirvožemio tarša sunkiaisiais metalais visame pasaulyje aktuali problema iki šiol neturinti universalaus sprendimo. Fitoremediacija – naujai atsirandanti ir daug žadanti technologija nestipriai užterštiems dirvožemiams valyti naudojant augalus. Šiame darbe dirvožemio valymui nuo sunkiųjų metalų pasirinktos trys žolinės augalijos rūšys – svidrė, miglė ir eraičinas, augintos modelinėmis laboratorinėmis sąlygomis vieną kartą ir periodiškai sunkiaisiais metalais teršiamuose dirvožemiuose. Nustatyta, kad geriausiai sunkiuosius metalus iš dirvožemio sorbuoja ir didžiausias dirvožemio valymo efektyvumas pasiekiamas naudojant svidrę. Augalijai sorbuojant sunkiuosius metalus iš dirvožemio dalis šių metalų (Cu, Cr, Zn, Pb, Mn, Ni) koncentruojasi žolinės augalijos šaknyse, tačiau didžioji dalis ten susikaupiančių metalų (iki 90 proc.) pereina į antžeminę augalo dalį. Didžiausios sunkiųjų metalų koncentracijos augale (iki 60 proc. ir daugiau) ir atitinkamai efektyviausias dirvožemio valymas nustatytas svidrės atveju, todėl sudarant mišinį didžiąją dalį (80 proc.) jame sudaro svidrė. Sunkiųjų metalų mišinys daro neigiamą įtaką vaivorykštinio upėtakio jauniklių fiziologiniams ir morfologiniams rodikliams, todėl didinat sunkiųjų metalų mišinio koncentracijas (iki 0,198–5,12 g/l) jos tampa letalinėmis vaivorykštiniams upėtakiams, tuo pačiu ir kitiems vandens gyvūnams. Pagal tyrimų su vaivorykštiniais upėtakiais rezultatus nustatyta, kad stebimų upėtakių, gyvenusių akvariume, užterštame 5,7... [toliau žr. visą tekstą] / Soil contamination with heavy metals is a problem of worldwide concern that is still unsolved. The analysis of the current methods of soil cleaning from heavy metals leads to conclusions that phytoremediation, i.e. soil decontamination by using plants, is one of the best methods. Although this method has not received a wide application yet and possibilities of its application are still being analysed, it is one of the most prospective soil cleaning methods due to low cost and a rather efficient cleaning of the upper surface of soil. Three kinds of Poaceae f. Species – Lolium perenne L., Poa pratensis L. and Festuca pratensis Huds. – have been chosen in this work for decontaminating soil from heavy metals. These plants were grown under artificial laboratory conditions in soil which was once and periodically contaminated with heavy metals. It was established that it is the Lolium perenne L. that most efficiently removes heavy metals and cleans soil. The results of experiments show that the selected grassy plants (perennial ryegrass, meadow-grass and fescue-grass) efficiently clean soil from heavy metals (copper, lead, manganese, zinc, nickel and chromium) when soil contains both low (0.5–120 mg/kg) and high (up to 6,850 mg/kg) concentrations of these metals. Since the perennial ryegrass absorbs the highest amount of heavy metals, the highest efficiency of soil cleaning is achieved using this plant, therefore, 80 % of the mixture of grassy plants was formed of the perennial... [to full text]

Les hydrocarbures aromatiques polycycliques (HAP) sont des polluants organiques persistants potentiellement mutagènes et cancérigènes. Leur transfert de l’atmosphère vers les écosystèmes, notamment vers les plantes, conditionne leur entrée dans les chaines alimentaires mais les modalités de ce transfert restent encore mal connues. L’objectif de ce travail était donc de caractériser le transfert et d’identifier les effets biologiques des HAP atmosphériques sur un système sol-plante-microorganismes symbiotiques.Un dispositif expérimental a été conçu afin de recréer en laboratoire une pollution atmosphérique par les HAP avec comme HAP modèle le phénanthrène (PHE). Le dispositif a fait l’objet d’une validation et d’une calibration élaborée de manière originale par une double approche mêlant l’expérimental à la simulation mathématique. Les niveaux d’exposition en polluant (150 µg m-3), contrôlés par des échantillonneurs passifs, se sont avérés pertinents par rapport aux conditions in situ. Ce dispositif a donc été utilisé pour exposer durant un mois des microsystèmes sol-plante-microorganismes au PHE par voie atmosphérique.Les différentes études ont mis en évidence un transfert du PHE depuis l’atmosphère vers tous les compartiments du microsystème, avec une accumulation majeure vers les feuilles de trèfle ou de ray-grass (respectivement 170 et 70 µg g־ ¹MS) et un transfert phloémien vers les racines est suggéré. Chez le trèfle, la mycorhization n’a pas été affectée, tandis que le nombre de nodules actifs a diminué de manière significative. Contrairement aux racines, la biomasse aérienne du trèfle a été significativement affectée (environ – 25%) par l’exposition au PHE atmosphérique, suggérant un impact sur le métabolisme carboné de la plante. Une expérience de marquage des trèfles au ¹³C-CO2 a effectivement montré un impact négatif du PHE atmosphérique sur la croissance, l’allocation de biomasse et l’allocation carbonée. Pour conclure, ces études ont permis non seulement de caractériser les effets biologiques et physiologiques des HAP atmosphériques sur les végétaux mais également de proposer l’utilisation du potentiel mycorhizien comme indicateur de pollution atmosphérique par les HAP. / Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants potentially mutagenic and carcinogenic. Transfer from the atmosphere to ecosystems, especially to plants, conditioning their entry into food chains, but the terms of this transfer are still poorly understood. The aim of this study was to characterize the transfer and identify the biological effects of atmospheric PAHs on soil-plant-symbiotic microorganisms.An experimental device was designed to recreate in the laboratory air pollution with phenanthrene (PHE) as a model PAH. The device was been validated and a calibration developed in an original way by a dual approach combining the experimental mathematical simulation. The levels of exposure to pollutant (150 mg m־³), controlled by passive samplers, were relevant with field conditions. This device has been used to expose a month of the soil-plant micro-organisms in the PHE through the air.Various studies have demonstrated a transfer of PHE from the atmosphere to all compartments of the microsystem, with a major accumulation to leaves in clover or ryegrass (respectively 170 and 70 µg g ־¹ dry weight) and a phloemic transfer to the roots is suggested. In clover, mycorrhization was not affected, while the number of active nodules decreased significantly. Unlike roots, aboveground biomass of clover was significantly affected (approximately – 25%) by exposure to air PHE, suggesting an impact on the carbon metabolism of the plant. A labelling experiment with ¹³C- CO2 in clover has actually shown a negative impact of PHE air on growth, biomass and carbon allocation.In conclusion, these studies have not only characterized the biological and physiological effects of atmospheric PAHs on plants but also proposed the use of mycorrhizal potential as an indicator of air pollution by PAHs.

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.