Optimization of timing of next-generation emergence inAmaranthus hybridusis determined via modulation of seed dormancy by the maternal environment

Abstract

Emergence timing of weed species has critical ecological and agronomical implications. In several species, emergence patterns largely depend on the seedbank dormancy level, which is modulated by specific environmental factors. In addition, environmental conditions during seed maturation on the mother plant have shown marked effects on dormancy level at seed dispersal time. Thus, maternal environment has been suggested to affect seedbank dormancy dynamics and subsequent emergence. However, this modulation has been barely analyzed under field conditions, and the mechanisms involved are only partly understood. Combining lab and field assays with population-based models, we investigated how dormancy level and emergence in the field are affected by mother plant sowing date and photoperiod extent in Amaranthus hybridus, a troublesome worldwide weed. Results showed that an earlier sowing date and a longer photoperiod enhanced dormancy level by increasing embryo- and seed-coat imposed dormancy. However, these variations in dormancy level did not affect the timing and extent of emergence in the field; on the contrary, they contributed to synchronize next generation emergence with the time period which maximizes population fitness. These results largely coincide with effects observed in other species such as Polygonum aviculare and Arabidopsis thaliana, suggesting a common effect on different species.

Thermal regulation of dormancy in Echinochloa crus‐galli (L.) P. Beauv. seeds: Development of a model to predict the temporal ‘window’ of emergence in the field

“…Our results showed that for this species the changes in the range of temperatures permissive for seed germination were mainly explained by changes in T l(50) , and that the rate at which T l(50) decreased, depended on the stratification temperature. Similar response patterns were found for the spring-summer annuals Polygonum aviculare (Batlla & Benech-Arnold, 2003;Malavert et al, 2017) and Amaranthus hybridus (Fernández Farnocchia et al, 2021). Changes in T l(50) were used to establish a functional relationship between the temperature experienced by the seeds during burial in the soil and the rate of dormancy alleviation to predict the emergence in the field (Figure 5).…”

Distinct hormonal and morphological control of dormancy and germination in Chenopodium album dimorphic seeds

“…40 µm was observed for the ND brown #1 seeds. In addition to day length also temperature during mother plant reproduction is known to affect coat-imposed dormancy for example of Amaranthus hybridus ( Figure 8D and Fernández Farnocchia et al., 2021 ) and of A. thaliana ( MacGregor et al., 2015 ).…”

“…The life-history strategy of weeds seems to be a blend of phenotypic plasticity and local adaptation for which within-species and within-seedlot variation in seed dormancy depth, as well as variation in dormancy release requirements are key to weed emergence timing ( Baskin and Baskin, 2006 ; Walck et al., 2011 ; Batlla et al., 2020 ). The primary dormancy of freshly harvested mature seeds is established during seed maturation and its depth depends on the environmental conditions during the mother plant’s reproductive growth ( Karssen, 1970 ; Penfield and MacGregor, 2017 ; Fernández Farnocchia et al., 2021 ). The control of germination by dormancy can be considered as block(s) to the completion of germination of an intact viable seed under otherwise favorable conditions, namely when the seed becomes non-dormant ( Finch-Savage and Leubner-Metzger, 2006 ).…”

“…In general, the brown seeds were found to be non-dormant and more salt-tolerant compared to the dormant black seeds which form a persistent soil seed bank. Amaranthaceae seed internal structure is characterized by a peripheral embryo and by variation of seed coat thickness which determines the coat-imposed physiological dormancy ( Karssen, 1970 ; Baskin and Baskin, 2019 ; Fernández Farnocchia et al., 2021 ; Nakabayashi and Leubner-Metzger, 2021 ).…”

Xyloglucan remodelling enzymes and the mechanics of plant seed and fruit biology

“…arabicum fruit and seed morphs ( Lenser et al ., 2016 ). Temperature and photoperiod contribute to population fitness by affecting seed coat cell wall properties (thickness, proanthocyanidin content) and thereby dormancy in other species ( Finch-Savage et al , 2006 ; Mizzotti et al , 2014 ; MacGregor et al , 2015 ; Fernández Farnocchia et al , 2021 ). The cell wall is a highly dynamic and adjustable structure, and its biomechanical properties are determined by specific cell wall compositions for which new modelling approaches are being pursued (B.…”