Kumssa Diriba B, Lovatt J Alan, Graham Neil S, Palmer Sarah, Hayden Rory, Wilson Lolita, Young Scott D, Lark R Murray, Penrose Beth, Ander E Louise, Thompson Russell, Jiang Lin-Xi, Broadley Martin R
School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, UK.
Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, UK.
Plant Soil. 2020;457(1):25-41. doi: 10.1007/s11104-019-04337-x. Epub 2019 Dec 2.
Magnesium (Mg) deficiency (known as grass tetany) is a serious metabolic disorder that affects grazing ruminants. We tested whether Mg-fertiliser can increase Mg concentration of Italian ryegrasses ( L.) including a cultivar (cv. Bb2067; 'Magnet'), bred to accumulate larger concentrations of Mg.
Under controlled environment (CE) conditions, three cultivars (cv. Bb2067, cv. Bb2068, cv. RvP) were grown in low-nutrient compost at six fertiliser rates (0-1500 μM MgCl.6HO). Under field conditions, the three cultivars in the CE condition and cv. Alamo were grown at two sites, and four rates of MgSO fertiliser application rates (0-200 kg ha MgO). Multiple grass cuts were taken over two-years.
Grass Mg concentration increased with increasing Mg-fertiliser application rates in all cultivars and conditions. Under field conditions, cv. Bb2067 had 11-73% greater grass Mg concentration and smaller forage tetany index (FTI) than other cultivars across the Mg-fertiliser application rates, sites and cuts. Grass dry matter (DM) yield of cv. Bb2067 was significantly ( < 0.05) smaller than cv. Alamo. The effect of Mg-fertiliser rate on DM yield was not significant ( ≥ 0.05).
Biofortification of grass with Mg through breeding and agronomy can improve the forage Mg concentration for grazing ruminants, even in high-growth spring grass conditions when hypomagnesaemia is most prevalent. Response to agronomic biofortification varied with cultivar, Mg-fertiliser rate, site and weather. The cost:benefit of these approaches and farmer acceptability, and the impact on cattle and sheep grazing on grasses biofortified with Mg requires further investigation.
镁（Mg）缺乏症（称为草痉挛）是一种影响放牧反刍动物的严重代谢紊乱疾病。我们测试了镁肥是否能提高意大利黑麦草（Lolium multiflorum Lam.）的镁浓度，其中包括一个为积累更高浓度镁而培育的品种（品种Bb2067；“Magnet”）。
在可控环境（CE）条件下，三个品种（品种Bb2067、品种Bb2068、品种RvP）在低养分堆肥中以六种肥料施用量（0 - 1500 μM MgCl₂·6H₂O）种植。在田间条件下，CE条件下的三个品种和品种Alamo在两个地点种植，并设置了四种硫酸镁肥料施用量（0 - 200 kg ha⁻¹ MgO）。在两年内进行了多次刈割。
在所有品种和条件下，草中的镁浓度均随着镁肥施用量的增加而增加。在田间条件下，在镁肥施用量、地点和刈割次数范围内，品种Bb2067的草镁浓度比其他品种高11 - 73%，且牧草痉挛指数（FTI）更小。品种Bb2067的草干物质（DM）产量显著低于（P < 0.05）品种Alamo。镁肥施用量对DM产量的影响不显著（P ≥ 0.05）。
通过育种和农艺措施对草进行镁生物强化可以提高放牧反刍动物的牧草镁浓度，即使在低镁血症最普遍的高生长春季草条件下也是如此。对农艺生物强化的反应因品种、镁肥施用量、地点和天气而异。这些方法的成本效益、农民接受度以及对放牧镁生物强化草的牛羊的影响需要进一步研究。
