Abstract Wheat cultivar mixtures have a well-explored potential for improving crop diversity, yield stability, and agronomic features. However, it is unclear whether heterogeneity of phenological traits in such mixtures may help to cope with increasing environmental stresses and uncertainties. To investigate the option of using wheat cultivar mixtures with different ripening patterns for mitigating the adverse effects of post-anthesis water stress, a two-year field experiment was conducted during 2014−15 and 2015−16 growing seasons at the research field of School of Agriculture, Shiraz University, Iran. The factorial experiment was a Randomized Complete Block Design with 3 replicates, in which 15 mixture treatments including monocultures and every 11 possible mixtures of four early- to middle-ripening wheat cultivars were grown under two normal and post-anthesis deficit-irrigation conditions. The results indicated that under the stressful conditions, heterogeneity in the ripening pattern of mixtures was diminished. Consequently, dissimilarities in grain yields as well as various agronomic characteristics of mixture treatments were also lessened. Although cultivar mixtures showed some casual beneficial effects, such advantages were not consistent across all conditions. Besides, cultivar mixtures could not mitigate the post-anthesis water stress significantly. However, only when the total averaged values of Susceptibility Index across the two seasons were assessed, a tendency for decreasing SI (up to 5.9 %) was observed in response to the extended phenology, which may suggest further studies for investigating the cultivar mixtures in long-term cropping systems. Despite the general expectation for beneficial ecological services from cultivar mixtures, in many cases there were disadvantageous blends, which led to a considerable reduction in grain yield and water productivity in single growing seasons. Therefore, it is suggested that unless the performance, and preferably the involved mechanisms of cultivar mixtures are fully understood, use of blends as an alternative for conventional high-input wheat cropping systems may lead to adverse results.

中文翻译：

---

小麦品种混合物中的扩展物候可以减轻花后水分胁迫吗？

摘要 小麦品种混合物在改善作物多样性、产量稳定性和农艺性状方面具有充分探索的潜力。然而，尚不清楚此类混合物中物候性状的异质性是否有助于应对日益增加的环境压力和不确定性。为了研究使用具有不同成熟模式的小麦品种混合物来减轻花后水分胁迫的不利影响的选择，在 2014-15 和 2015-16 生长季节期间在该学院的研究领域进行了为期两年的田间试验。农业，设拉子大学，伊朗。析因实验是随机完整区组设计，有 3 个重复，其中 15 种混合处理，包括单一栽培和每 11 种可能的 4 种早熟至中熟小麦品种的混合处理，在两种正常和开花后亏缺灌溉条件下种植。结果表明，在压力条件下，混合物成熟模式的异质性减少。因此，谷物产量的差异以及混合物处理的各种农艺特征也减少了。尽管品种混合物显示出一些偶然的有益效果，但这些优势在所有条件下并不一致。此外，栽培品种混合物不能显着减轻花后水分胁迫。然而，仅当评估两个季节的易感性指数的总平均值时，SI 呈下降趋势（高达 5. 9 %) 观察到对扩展物候的响应，这可能表明需要进一步研究以研究长期种植系统中的栽培品种混合物。尽管人们普遍期望从品种混合物中获得有益的生态服务，但在许多情况下存在不利的混合物，这导致单个生长季节的谷物产量和水分生产力显着降低。因此，建议除非充分了解品种混合物的性能，最好是所涉及的机制，否则使用混合物作为传统高投入小麦种植系统的替代品可能会导致不利结果。尽管人们普遍期望从品种混合物中获得有益的生态服务，但在许多情况下存在不利的混合物，这导致单个生长季节的谷物产量和水分生产力显着降低。因此，建议除非充分了解品种混合物的性能，最好是所涉及的机制，否则使用混合物作为传统高投入小麦种植系统的替代品可能会导致不利结果。尽管人们普遍期望从品种混合物中获得有益的生态服务，但在许多情况下存在不利的混合物，这导致单个生长季节的谷物产量和水分生产力显着降低。因此，建议除非充分了解品种混合物的性能，最好是所涉及的机制，否则使用混合物作为传统高投入小麦种植系统的替代品可能会导致不利结果。