Whole plant acclimation responses by finger millet to low nitrogen stress

Abstract

The small grain cereal, finger millet (FM, Eleusine coracana L. Gaertn), is valued by subsistence farmers in India and East Africa as a low-input crop. It is reported by farmers to require no added nitrogen (N), or only residual N, to produce grain. Exact mechanisms underlying the acclimation responses of FM to low N are largely unknown, both above and below ground. In particular, the responses of FM roots and root hairs to N or any other nutrient have not previously been reported. Given its low N requirement, FM also provides a rare opportunity to study long-term responses to N starvation in a cereal species. The objective of this study was to survey the shoot and root morphometric responses of FM, including root hairs, to low N stress. Plants were grown in pails in a semi-hydroponic system on clay containing extremely low background N, supplemented with N or no N. To our surprise, plants grown without deliberately added N grew to maturity, looked relatively normal and produced healthy seed heads. Plants responded to the low N treatment by decreasing shoot, root, and seed head biomass. These declines under low N were associated with decreased shoot tiller number, crown root number, total crown root length and total lateral root length, but with no consistent changes in root hair traits. Changes in tiller and crown root number appeared to coordinate the above and below ground acclimation responses to N. We discuss the remarkable ability of FM to grow to maturity without deliberately added N. The results suggest that FM should be further explored to understand this trait. Our observations are consistent with indigenous knowledge from subsistence farmers in Africa and Asia, where it is reported that this crop can survive extreme environments.

Evaluating pearl millet and mungbean intercropping in the semi‐arid regions of Senegal

“…Yield differences across sites in the present study are likely a result of more rainfall at Nioro 2018 As demonstrated by several authors, rainfall plays a critical role in crop growth and yields under rainfed agriculture (Biazin, Sterk, Temesgen, Abdulkedir, & Stroosnijder, 2012;Rockström, Barron, & Fox, 2003). Although grain yield has been reported to be positively correlated with biomass production in millet (Goron, Bhosekar, Shearer, Watts, & Raizada, 2015;Muchow, 1989), we observed the opposite in the present study. Millet produced higher grain yield and lower dry biomass at Nioro 2018, while millet plants yielded less grain but had higher stem, leaf, panicle, and dry biomass at Bambey 2017.…”

Leaf and Root Growth, Carbon and Nitrogen Contents, and Gene Expression of Perennial Ryegrass to Different Nitrogen Supplies

“…1). It could be more related to lowering shoot density in grass plants under low N (Goron et al, 2015). Across 10 cool-season grass species in a controlled environment, plants responded to low N by decreasing shoot and root growth, but to a greater extent in shoots, resulting in an increase in root:shoot ratio (Skinner and Comas, 2010).…”

“…For warm-season grasses, st. augustinegrass (Stenotaphrum secundatum) had greater N partitioning to roots than bermudagrass (Cynodon dactylon), bahiagrass (Paspalum notatum), and zoysiagrass (Zoysia japonica) based on root length, root:shoot ratio, and N content in roots, suggesting that st. augustinegrass has a potential for improved N retention in roots (Poudel et al, 2013). In finger millet (Eleusine coracana), declines in shoot and root growth under low N were associated with decreased shoot tiller number, crown root number, total crown root length, and total lateral root length, but with no consistent changes in root hair traits (Goron et al, 2015). The results demonstrate that lower reductions in root growth and related morphological changes are important traits for adaptation of plants to a low-N environment.…”

Mid-Season Leaf Glutamine Predicts End-Season Maize Grain Yield and Nitrogen Content in Response to Nitrogen Fertilization under Field Conditions

“…), a crop important in agroecosystems of the semi-arid tropics [61][62][63]. GlnLux glutamine content in finger millet leaves sampled 39 days after germination displayed tight correlation with grain yield across a range of N application rates (Supplementary Materials Figure S3C-E), conducted as part of a larger study in which N limitation effects on plant morphology were examined [64].…”