Interactions Between Environment and Genetic Diversity in Perennial Grass Phenology: A Review of Processes at Plant Scale and Modeling

Abstract

In perennial grasses, the reproductive development consists of major phenological stages which highly determine the seasonal variations of grassland biomass production in terms of quantity and quality. The reproductive development is regulated by climatic conditions through complex interactions subjected to high genetic diversity. Understanding these interactions and their impact on plant development and growth is essential to optimize grassland management and identify the potential consequences of climate change. Here, we review the main stages of reproductive development, from floral induction to heading, i.e., spike emergence, considering the effect of the environmental conditions and the genetic diversity observed in perennial grasses. We first describe the determinants and consequences of reproductive development at individual tiller scale before examining the interactions between plant tillers and their impact on grassland perenniality. Then, we review the available grassland models through their ability to account for the complexity of reproductive development and genetic × environmental interactions. This review shows that (1) The reproductive development of perennial grasses is characterized by a large intraspecific diversity which has the same order of magnitude as the diversity observed between species or environmental conditions. (2) The reproductive development is determined by complex interactions between the processes of floral induction and morphogenesis of the tiller. (3) The perenniality of a plant is dependent on the reproductive behavior of each tiller. (4) Published models only partly explain the complex interactions between morphogenesis and climate on reproductive development. (5) Introducing more explicitly the underlying processes involved in reproductive development in models would improve our ability to anticipate grassland behavior in future growth conditions.

Maintaining grain yield of Th. intermedium across stand age through constant spike fertility and spike density: Understanding its response to various agronomic managements

“…Indeed, previous studies have highlighted a decline in yield with stand age, combined with a decrease in spike density (Jungers et al, 2017;Law et al, 2020). Authors hypothesized that changes in light quality perceived by the axillary buds located at the bases of the plant, which could reduce reproductive tiller initiation or trigger light avoidance syndrome, might be the cause (Jungers et al, 2017;Pinto et al, 2021;Rouet et al, 2021). Different management practices to increase light penetration to the canopy have previously been tested to maintain Th.…”

“…Although the developmental pattern and the regulation of tiller emergence have been investigated (Assuero & Tognetti, 2010), the way genetic and environmental factors interact to determine tiller fate and fertility is still largely unclear. In swards, among the important peculiarities of perennial grasses compared to annual cereals, we can identify i) a highly variable and often low proportion of fertile tillers with aging plants, resulting in grain yield decrease over years (Fulkerson, 1980;Jungers et al, 2017), ii) the marked influence of the period of appearance of tiller cohorts and the order of emergence of the tillers on their reproductive potential (Rouet et al, 2021), iii) an increased variability in floret site utilization (Elgersma, 1985;Altendorf et al, 2021) and iv) the potential competition between several sink organs at the end of the growing season (i.e., grains, rhizomes, bulbs, stolons or dormant buds) (Hay & Porter, 2006;Durand & Lafarge, 2011). These characteristics have fueled intense theoretical discussion as to whether physiological trade-offs between plant longevity and seed production can effectively be overcome through new agroecosystem design and modern breeding techniques (see for example DeHaan et al (2023)).…”

“…Defoliation performed above the apex height is known to preserve the tiller reproductive potential. Meanwhile, defoliation may generate new vegetative tillers and could eventually delay stem elongation or reduce tiller height (Mansat & Pfitzenmeyer, 1966;Gillet, 1973;Rouet et al, 2021). With respect to Th.…”

Weed community shifts during the aging of perennial intermediate wheatgrass crops harvested for grain in arable fields

“…Tillering is a complex process in grasses, as it is under multifactorial control (e.g., light quality, nutrient and water availability, defoliation regime, temperature; Assuero and Tognetti, 2010). This process is especially complex in perennial species, like IWG, for which the regulation of tiller emergence and differentiation in relation to environmental cues remain poorly understood (Lafarge and Durand, 2011;Rouet et al, 2021). Thus, more research is required to clarify tillering dynamics, which would allow appropriate management practices to be designed (e.g., planting design, mowing, grazing, fertilization, residue management) that maintain the production of fertile tillers over multiple growing seasons.…”