Harnessing the Potential of Wheat-Pea Species Mixtures: Evaluation of Multifunctional Performance and Wheat Diversity

Abstract

Species mixtures and heterogeneous crop populations are two promising approaches for diversified ecological cropping systems with increased resilience and reduced dependency on external inputs. Inter- and intraspecific diversity were evaluated in combination using 15 wheat (Triticum aestivum) entries, including line cultivars and heterogeneous populations (HPs), from central Europe and Hungary and one winter pea cultivar under organic conditions. Monocultures and wheat mixtures were evaluated multi-functionally for yield, quality, land use efficiency, crop protection, and wheat entry traits. Mixtures increased cereal grain quality, weed suppression, resource use efficiency, yield gain, and reduced lodging. Effects were stronger in 2018/19, which were characterized by dry and nutrient-poor conditions than in 2019/20 when nutrient levels were higher. Wheat entries varied considerably in protein content and yield in both mixtures and monocultures. Under higher nutrient availability, entry-based variation was reduced in both systems, and peas were suppressed. Because of low disease pressure, the wheat entries varied little in terms of disease protection services, and mixture effects on the disease were low. The multi-criteria framework identified stability of yield, yield gains, and quality under high environmental variability of mixtures as clear agronomic advantages with HPs being considerably more stable than line cultivars. Some line cultivars outperformed the HPs in either protein content or yield across environments but not both simultaneously. Trait analysis revealed a possible link between harvest index and reduced competition in mixtures, which can increase yield performance in specific line cultivars. System cultivar interactions were generally very low and highly dependent on environmental conditions. We conclude that while cultivar breeding for mixtures can be successful in monocultures, high environmental variation highlights the necessity of evaluating cultivars in mixtures. In addition, use of intraspecific diversity within interspecific mixed cropping systems can be a valuable addition to further improve mixture performance and its stability under increasing environmental stresses due to climate change.

Mixture × Genotype Effects in Cereal/Legume Intercropping

“…Furthermore, the ANOVA across cereal species and design indicated that different species have different land-use efficiency in the different design types with finger millet having higher land-use efficiency than other crops in additive designs, whereas no difference was observed between the species in replacement designs. The number of studies, which report LER from different wheat genotypes, was very limited [but see Timaeus et al (2022)]; because of the high importance of wheat for global food security, we suggest that more research is needed to investigate the performance of different wheat genotypes in intercropping. Conversely, the effect of design on land use efficiency in legumes is not significant, whereas species effect is significant.…”

“…In an additive design, the planting density of both species in the mixture may be equivalent or somewhat reduced compared to their sole stand resulting in planting densities leading to density equivalent ratios > 1 and up to 2. For example, pea-oat mixtures may be composed of 100% peas and 20% oats compared to the pure stand densities (Gronle et al, 2015) or wheat-winter pea mixtures of 70% wheat with 50% pea (Timaeus et al, 2022). In replacement designs, the density of one sole crop species is proportionally (based on sole crop densities) replaced by the other species resulting in a density equivalent ratio of 1.…”

Adoption of Food Species Mixtures from Farmers’ Perspectives in Germany: Managing Complexity and Harnessing Advantages

“…The broad range of aspects of PRP of mixtures indicates that SM performance was perceived multifunctionally. This is supported by empirical multifunctional SM evaluation [6]. Farmers that work under nutrient-limited conditions, especially in organic farming, focus on nutrient cycling and enhancing biological nitrogen fixation.…”

“…A prime example are wheat pea mixtures that are rarely used in practice [9] despite their manifold advantages, such as increased protein content in wheat and an additional yield of peas [6]. The usually discussed conundrum is the separation of baking wheat from mixtures.…”

“…Yields of legumecereal SMs can be more stable than yields of the respective sole crops [4] and considerable yield gains of mixtures were found in low and high-input farming systems [5]. In a recent experimental study, wheat-pea mixtures outperformed the respective sole crops within a multifunctional evaluation framework, including yields, resource efficiency, crop quality and crop protection, especially under challenging environmental conditions [6]. Despite this potential, in industrialized agriculture, SM are mostly confined to the niches of grassland and cover crop mixtures [7].…”