Background:Perennial ryegrass(Lolium perenne)in New Zealand pastures is typically infected with the mutualist Epichloëfungal endophyte.This endophyte assists the plant in resisting biotic and abiotic stresses,but...Background:Perennial ryegrass(Lolium perenne)in New Zealand pastures is typically infected with the mutualist Epichloëfungal endophyte.This endophyte assists the plant in resisting biotic and abiotic stresses,but the standard strain of endophyte is toxic to livestock.Elite ryegrasses with selected endophytes have been developed to provide protective properties to the grass plant and lessen or eliminate the negative impacts on livestock.Methods:Using immunology and molecular techniques,the presence of endophyte infection and endophyte strain in ryegrass tillers was determined for 24 dairy pastures sampled for up to 7 years in regions of the North and South Islands.Results:In general,infection levels were high and showed small increases over time.Some pastures failed to reach 70%infection.The sown,selected endophytes were the dominant endophyte strains present and these were stable over time.Standard endophyte was the primary nonsown endophyte,and while generally low and so of little importance,it increased over time and for some pastures,this would have been detrimental to livestock.Pasture establishment technique influenced the level of contamination.Conclusions:Results reinforce the importance of following best practice procedures in the seed industry and on-farm.Researchers should monitor trials for contaminating nonsown standard endophyte.展开更多
Background:Grazing approaches are needed to increase the resilience of perennial ryegrass(Lolium perenne L.)-based pastures subject to increasing drought stress.One opportunity has focused on seedhead management in la...Background:Grazing approaches are needed to increase the resilience of perennial ryegrass(Lolium perenne L.)-based pastures subject to increasing drought stress.One opportunity has focused on seedhead management in late spring.Paddock-level studies demonstrated increased pasture resilience when ryegrass seedheads are allowed to mature,but knowledge is lacking on how defoliation management affects plant carbohydrate status and hence resilience in the sward.Methods:A glasshouse study was conducted from spring to autumn using 1 m deep root tubes.Plant growth and water-soluble carbohydrate(WSC)reserves were measured every 46 weeks.Defoliation treatments comprised"VEGETATIVE"regular defoliation based on leaf stage and trimmed to 4 cm;"FLOWERING"no defoliation spring to anthesis;and"SENESCENT"no defoliation spring to reproductive tiller senescence.Thereafter,regular defoliation was carried out for all treatments until the end of the study.From spring to the end of summer,plants were watered daily in WET(no drought,well watered)and on four occasions in DRY(drought)treatments,with daily watering thereafter.Results:Herbage mass,tillering,root depth,root mass,and WSC were generally higher in SENESCENT than VEGETATIVE with FLOWERING intermediate(p<0.05).Nutritive values were similar in VEGETATIVE and FLOWERING,but in SENESCENT,metabolizable energy and crude protein declined and neutral detergent fiber increased(p<0.05).Soil moisture effects were small,with the DRY treatment resulting in moderate suppression of herbage growth and a minor reduction in WSC reserves(p<0.05).Conclusions:Results were consistent with field studies and recommendations to allow perennial ryegrass tillers to set seed to improve pasture resilience.展开更多
基金DairyNZNew Zealand Ministry for Agriculture and Forestry(MAF),Grant/Award Number:“Sustainable Farming Fund project 08/019–Best-Practice Pasture Renewal for Forage Production and Sustainability”AgResearch,Grant/Award Number:Strategic Science Investment Fund。
文摘Background:Perennial ryegrass(Lolium perenne)in New Zealand pastures is typically infected with the mutualist Epichloëfungal endophyte.This endophyte assists the plant in resisting biotic and abiotic stresses,but the standard strain of endophyte is toxic to livestock.Elite ryegrasses with selected endophytes have been developed to provide protective properties to the grass plant and lessen or eliminate the negative impacts on livestock.Methods:Using immunology and molecular techniques,the presence of endophyte infection and endophyte strain in ryegrass tillers was determined for 24 dairy pastures sampled for up to 7 years in regions of the North and South Islands.Results:In general,infection levels were high and showed small increases over time.Some pastures failed to reach 70%infection.The sown,selected endophytes were the dominant endophyte strains present and these were stable over time.Standard endophyte was the primary nonsown endophyte,and while generally low and so of little importance,it increased over time and for some pastures,this would have been detrimental to livestock.Pasture establishment technique influenced the level of contamination.Conclusions:Results reinforce the importance of following best practice procedures in the seed industry and on-farm.Researchers should monitor trials for contaminating nonsown standard endophyte.
文摘Background:Grazing approaches are needed to increase the resilience of perennial ryegrass(Lolium perenne L.)-based pastures subject to increasing drought stress.One opportunity has focused on seedhead management in late spring.Paddock-level studies demonstrated increased pasture resilience when ryegrass seedheads are allowed to mature,but knowledge is lacking on how defoliation management affects plant carbohydrate status and hence resilience in the sward.Methods:A glasshouse study was conducted from spring to autumn using 1 m deep root tubes.Plant growth and water-soluble carbohydrate(WSC)reserves were measured every 46 weeks.Defoliation treatments comprised"VEGETATIVE"regular defoliation based on leaf stage and trimmed to 4 cm;"FLOWERING"no defoliation spring to anthesis;and"SENESCENT"no defoliation spring to reproductive tiller senescence.Thereafter,regular defoliation was carried out for all treatments until the end of the study.From spring to the end of summer,plants were watered daily in WET(no drought,well watered)and on four occasions in DRY(drought)treatments,with daily watering thereafter.Results:Herbage mass,tillering,root depth,root mass,and WSC were generally higher in SENESCENT than VEGETATIVE with FLOWERING intermediate(p<0.05).Nutritive values were similar in VEGETATIVE and FLOWERING,but in SENESCENT,metabolizable energy and crude protein declined and neutral detergent fiber increased(p<0.05).Soil moisture effects were small,with the DRY treatment resulting in moderate suppression of herbage growth and a minor reduction in WSC reserves(p<0.05).Conclusions:Results were consistent with field studies and recommendations to allow perennial ryegrass tillers to set seed to improve pasture resilience.
