本文以内蒙古锡林浩特市毛登牧场人工草地试验小区为试验点，选择豆科牧草紫花苜蓿（Medicago sativa）、禾本科牧草无芒雀麦（Bromus inermis）和垂穗披碱草（Elymus nutans）三种牧草，采用单播和混播两种不同的播种方式，根据牧草的不同生育期，设置四个不同的灌溉水分处理梯度，通过测定牧草生产力、竞争能力、光合特性、荧光特性、光能利用、水分利用以及牧草营养品质等特性，分析不同牧草对不同处理的反应机理以及播种方式和灌溉对牧草生产力和草质的影响，初步探讨适合三种优良牧草生长特点的灌溉制度和播种方式，为人工草地建植初步确定一个合适的建植方案，结果表明：播种方式的不同对牧草的生产力以及牧草品质有极为重要的影响。豆禾混播的比例适宜适宜，品种选择恰当，有利于提高禾本科的生产力和草质。无芒雀麦和垂穗披碱草与紫花苜蓿以2:1的混播模式下，提高了牧草生产力，在一定程度上避免了种间竞争，两种混播模式草地整体呈现出协调生长关系。在光合能量分配方面，无论是单播还是混播，紫花苜蓿的光合速率较高，将天然色素吸收的能量更多的用于光化学反应进行光合作用。两种禾本科牧草，在混播模式下，通过改变对其能量分配调整，把更多的能量用于P，提高光合效率，减少了过剩光能对牧草光合机构的损害，从而提高了光合能力。相较禾本科牧草，豆禾混播整体提高了牧草的粗蛋白含量，降低了纤维素含量，有利于牧草营养价值的提高。因此，不同播种方式改变了牧草的生长特性，豆禾混播在一定程度上提高了草地的生产力和品质。 不同水分处理下，牧草生物量差异较大。紫花苜蓿对水分反映较为敏感，6月底至7月初属于紫花苜蓿的关键需水期，此时灌溉效果最好，总灌溉量在66.65mm左右，既节约水分又提高了牧草生物量，灌溉之后7、8月份紫花苜蓿生物量较高，适合刈割。无芒雀麦在7月底8月初的拔节期灌溉增产效益高，总灌溉量为99.02mm。灌溉之后8月份进行刈割产量最高。紫花苜蓿和无芒雀麦混播，拔节期灌溉之后进行刈割较为合适，总灌溉量为44.49mm。垂穗披碱草8月份灌溉有助于生物量提高。而紫花苜蓿和垂穗披碱草混播时，拔节期灌水之后再刈割较为合适。总灌溉量均为99.02mm。通过对水分和生物量模拟，随着补水量的增加，牧草的地上生物量随着上升。当统一灌溉时，灌溉水量在160-180mm范围，牧草整体生物量较高。灌水对牧草品质影响不完全相同，灌水在一定程度上提高了粗蛋白含量。紫花苜蓿对水分反应较敏感。经过灌溉补水后紫花苜蓿将更多的能量用于光合作用，光饱和点和表观量子效率提高，光补偿点和暗呼吸速率降低，呼吸消耗降低，有利于同化物累积，从而提高生产力。单播无芒雀麦对水分的反应也较敏感，将更多的能量用于光合反应中心，提高光饱和点，降低暗呼吸，从而提高光合能力。混播无茫雀麦对灌溉不敏感，但与单播相比，混播后光饱和点增高，补偿点降低，暗呼吸降低，提高了其耐阴性，因此无茫雀麦适合混播。垂穗披碱草混播后光合能力提高，高光合、低消耗，有利于牧草生长和生物量的有效累积。补水灌溉在一定程度上提高了牧草的光合能力，三种牧草在补水之后净光合速率都有所提高，而补水较多的牧草荧光能量更多用于光合反应中心提高牧草的光合能力和用来进行天然色素热耗散避免对叶片光合机构的损害。尤其是雨养条件下，三种牧草都是通过降低蒸腾、增加牧草根冠比来降低水分散失、提高水分利用能力，极力吸收土壤深层水分，这是植物抗干旱胁迫的响应机制。不同水分处理对叶片营养元素影响不大，豆科牧草和豆禾混播下N含量较高，C含量较低，有利于光合作用和生物量累积。禾本科牧草单播N含量较低，C含量较高，N吸收受到一定限制，生长速率较慢，是植物抵抗环境胁迫的响应机制。

The sown grassland of the Maodeng Pasture served as the experimental area in this research, and the forage species included a legume, Medicago sativa, and two grasses, Bromus inermis and Elymus nutans. In the present study, we created monocultures of each species, a mixture of Medicago sativa and Bromus inermis, and a mixture of Medicago sativa and Elymus nutans. According to the different growth period of the forage, we set four different water treatments. This paper has compared the impact of different sowing methods and water treatments on the forage growth by determining and analyzing the yield, photosynthetic characteristics, fluorescence energy distribution and nutritive value of the forage. It aims to determine the corresponding adaptation mechanism of the forage and provide a scientific basis for species selection, irrigation system and the establishment of high-yield sown grasslands with high nutritive quality. Some main conclusions are obtained as follows:The different sowing methods significantly affected both forage production and the forage quality. An appropriate grass-legume mixture and an appropriate selection of plant species can therefore improve grass production and quality. The mixture of Bromus inermis and Elymus nutans with Medicago sativa in a proportion of 2:1 improved the forage productivity and decreased interspecies competition to some extent. The species therefore appear to have adapted to each other by exploiting somewhat different niches, thereby benefiting both the legume and the grasses. The distribution of captured light energy supported a higher photosynthetic rate for Medicago sativa, with more of the absorbed energy used to support photosynthesis. In the mixed sowing, both species distributed more energy to P, thereby increasing the photosynthetic efficiency and decreasing the damage caused by excessive light energy. The grass-legume mixture generally increased the crude protein content of the forage and decreased or did not affect its cellulose and lignin contents, resulting in an overall improvement of the nutritive value of the forage compared with the corresponding monoculture. Thus, the grass-legume mixtures improved both the productivity and nutritive quality of the grassland. Under different water treatments, the forage biomass is different. Medicago sativa is sensitive to water. From the end of June to early July, Medicago sativa need enough water and it is good time to irrigate. After irrigating, it is good to cut. The total irrigation is 66.65mm. For Bromus inermis, it is good to irrigate form the end of July to early August. After irrigating, the forage need to be cut. The total irrigation is 99.02mm. So is Elymus nutans. For Medicago sativa and Bromus inermis, the total irrigation is 44.49mm. Overall, the aboveground biomass of the forage increases with the water increases. When the water is 160-180mm, all the forage biomass are high. Irrigation affects the forage quality by increasing the crude protein content. Medicago sativa is sensitive to water. After irrigation, it put the more energy on the photochemical reactions to promote the LSP and AQY and decrease the LCP and Rd. It is good to accumulation assimilation and improve productivity. So is Bromus inermis. After mixing, Bromus inermis is not sensitive to water and it has higher LSP, lower LCP and Rd. It has good shade tolerance and is good to mix with Medicago sativa. In some content, irrigation improves the photosynthesis of the forage. After mixing, Elymus nutans has high photosynthesis and low consume to improve biomass accumulation and growth. When irrigate more water, the more energy absorbed by the natural pigments are used for the photochemical reactions to promote the photosynthesis and reducing the damage of excessive light energy on the photosynthetic apparatus of the forage. When irrigating, the photosynthesis of the forage increases showing that irrigation promotes the growth. Irrigation affects the root growth and the root-shoot ratio becomes bigger without irrigation to absorb more water and adjust the lack of water. Under different water treatments, the leaf nutrients did not change significantly. The LTN of legume and legume-grass mixture is high and the LTC is low which is conductive to photosynthesis and biomass accumulation. The LTN of grass is low and the LTC is high, which means the growth rate is slower and the N absorption is restrictive which is a mechanism to environmental stress.