Nitrogen Fertilization Increases Root Growth and Coordinates the Root–Shoot Relationship in Cotton

Abstract

The root system plays an important role in the growth and development of cotton, and root growth is closely related to shoot growth, both of which are affected by N availability in the soil. However, it is unknown how N affects root growth and the rootshoot relationship under various N rates in the Yellow River Basin, China. Thus, the aim of this study was to assess the impacts of the application rate of N on root growth and the root-shoot relationship, to provide insight into the N regulation of root and shoot growth and N efficiency from the perspective of the root system. A field experiment conducted in 2014 and 2015 was used to determine the effects of N rates (0, 120, 240, and 480 kg ha −1) on root morphology, root distribution, the root-shoot relationship, and cotton yield. A moderate N fertilization rate (240 kg ha −1) increased root length, root surface area, and root biomass in most soil layers and significantly increased total root growth and total root biomass by more than 36.06% compared to the 0 kg ha −1 treatment. In addition, roots in the surface soil layers were more strongly affected by N fertilization than roots distributed in the deeper soil layers. Total root length, total root surface area, and root biomass in the 0-15 cm layer were significantly correlated with shoot biomass and boll biomass. In the 60-75 cm layer, total root length, total root surface area, and root length were significantly positively correlated with seed cotton yield. The application of a moderate level of N markedly increased total shoot biomass, boll biomass, and seed cotton yield. Our results show that increased shoot and boll biomasses were correlated with a significant increase in the root system especially the shallow roots in the moderate N treatment (240 kg ha −1), leading to an increase in cotton seed yield.

The Application of Z-Ion Substrate to Support Energy Crop Growth (<i>Dactylis Glomerata</i> L.) on Degraded Soil

“…This phenomenon is consistent with the regularity described in the literature, according to which, as the doses of some nutrients, e.g. nitrogen (present as NH 4 + in the Z-ion substrate) are increased, the above-ground biomass of plants increases as well, while the root mass may not, and sometimes it even decreases [Chen et al 2017, Chen et al 2020].…”

Root Biomass Distribution of Populus sibirica and Ulmus pumila Afforestation Stands Is Affected by Watering Regimes and Fertilization in the Mongolian Semi-arid Steppe

“…Similarly, the reduction of root growth measured in plants grown with NPK addition might be related to the high application rate, which led to a large quantity of urea-based fertilizer considered phytotoxic (Chen et al, 2020). Also, high N fertilizer application rates to such an early growth stage of seedlings, may induce a growth priority to the aboveground structure, thereby repressing root growth without affecting shoot biomass (Dong et al, 2008;Rogato et al, 2010;Zhang et al, 2017).…”

Ramularia leaf spot and Boll rot are affected differently by organic and inorganic nitrogen fertilization in cotton plants

“…However, the same authors mention that this effect was generated only by some nitrogenous sources, such as potassium nitrate (KNO 3 ), which negatively affects the diameter of lesions but not the severity. Also, applications of different forms of N, such as ammonia (NO 3 ) and ammonium (NH 4 ), can act biochemically, physiologically, and molecularly in a different way in plants against pathogens (Sun et al, 2020). In this way, it can be inferred that both some external factor and an effect at the cellular level of each fertilizer in cotton plants may have in uenced the behavior observed in our work.…”

“…However, the r for RLS incidence was only lower in plants fertilized with urea, compared to the rest of the nitrogen sources. Although the increase or reduction of disease due to nitrogen fertilization (NH 4 , NO 3, or another source), forms of N can act biochemically, physiologically, and molecularly in a differentiated way in plants (Sun et al 2020). However, this may vary in other species.…”