Lolium perenne L. (Lp) is the main pasture species in New Zealand, but climate change increases the likelihood of drought during summer and consequently lowers its growth rates. Bromus valdivianus Phil. (Bv) tolerates better the summer soil water restriction, but its competitiveness in a diverse pasture relates to the defoliation management and soil moisture levels. The performance of both species in terms of production, persistence and feed quality across seasons under different defoliation regimens was evaluated when the species were mixed and in monoculture. The treatments were applied in a randomised complete block design with three blocks. Bromus valdivianus and Lp monocultures and the 50/50 mixture (Mx) were grazed at low and high defoliation frequencies (i.e. based on Bv and Lp optimal leaf regrowth stage [LS], respectively). Herbage mass production was 15% higher in the Mx, mainly due to an increase in production in spring and summer. In spring, there was complementarity growth between the species, while during summer/early autumn, the Mx production relayed in the higher participation of Bv. Root biomass at depth (31–70 cm) was 38% greater for Bv monoculture and the Mx compared with Lp monoculture, which demonstrated the contribution of Bv to a better production of the mixture during and following the dry periods. In addition, the maintenance of the Bv tiller population and the higher growth rate during dry periods demonstrated its better fitness to low soil water availabilities than Lp. Although herbage mass was not modified by the defoliation frequency, forage quality of Bv showed values at low defoliation frequency that could compromise animal production during spring. However, there was an increase in root biomass under low defoliation frequencies, which suggested that a flexible grazing management across seasons would increase the niche utilisation between species in the mixture. The defoliation frequency of the mixture could be based on Lp LS during spring and winter, and slowed down, following Bv criteria, during summer and autumn.

中文翻译：

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两种多年生禾本科植物在叶片再生阶段落叶标准下提高牧草产量和抗旱性的功能贡献

多年生黑麦草(Lp) 是新西兰的主要牧草物种，但气候变化增加了夏季干旱的可能性，从而降低了其生长速度。Bromus valdivianus菲尔。(Bv) 对夏季土壤水分限制的耐受性更好，但其在多样化牧场中的竞争力与落叶管理和土壤水分水平有关。当物种混合和单一栽培时，在不同脱叶方案下评估两个物种在不同季节的生产、持久性和饲料质量方面的表现。治疗应用于具有三个区组​​的随机完整区组设计。野雀麦和 Lp 单一栽培和 50/50 混合物 (Mx) 在低和高落叶频率下放牧（即分别基于 Bv 和 Lp 最佳叶片再生阶段 [LS]）。Mx 的牧草产量增加了 15%，这主要是由于春季和夏季的产量增加。在春季，物种之间存在互补性增长，而在夏季/初秋，Mx 的生产依赖于 Bv 的更高参与度。与 Lp 单一栽培相比，Bv 单一栽培和 Mx 深度（31-70 厘米）的根生物量高 38%，这表明 Bv 对在干旱期间和之后更好地生产混合物的贡献。此外，Bv 分蘖种群的维持和干旱时期较高的生长率表明它比 Lp 更适合低土壤水分有效性。尽管牧草质量未因落叶频率而改变，但 Bv 的牧草质量在低落叶频率下表现出值，这可能会影响春季的动物生产。然而，在低落叶频率下根系生物量增加，这表明跨季节灵活的放牧管理将增加混合物中物种之间的生态位利用。混合物的落叶频率在春季和冬季可基于 Lp LS，并在夏季和秋季根据 Bv 标准减慢。这表明跨季节的灵活放牧管理将增加混合物中物种之间的生态位利用。混合物的落叶频率在春季和冬季可基于 Lp LS，并在夏季和秋季根据 Bv 标准减慢。这表明跨季节的灵活放牧管理将增加混合物中物种之间的生态位利用。混合物的落叶频率在春季和冬季可基于 Lp LS，并在夏季和秋季根据 Bv 标准减慢。