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Enhancing Uptake and Translocation of Systemic Active Ingredients
Published in Chester L. Foy, David W. Pritchard, and Adjuvant Technology, 2018
Roger J. Field, Farhad Dasigheib
Root uptake of pesticides is similar to ion and nutrient uptake and the concepts developed from studies of ion uptake are usually applied to all compounds. The large surface area of the roots and the ability of plants to produce new root hairs at rapid rates provides plants with an extremely efficient uptake system.91 Root hairs play the most important part in absorption of substances from the soil, although absorption by other regions of the root occurs. The external wall of the root hair, like the epidermis of the leaf, is covered with a layer of cuticle, although it is very thin.33,173 Solutes and water readily pass through this barrier by mass flow and/or diffusion and enter the cell wall where they will be available for transport in the apoplast. Active uptake of herbicides and their transfer through the symplast is known to occur and is an essential step in the mode of action of herbicides.55
Microbial Bioinoculants for Sustainable Agriculture
Published in Ram Chandra, R.C. Sobti, Microbes for Sustainable Development and Bioremediation, 2019
Azospirillum has been largely and extensively used for crop plants belonging to family Gramineae such as wheat, sorghum, pearlmillet, fingermillet, barley, and maize; however, its response has been found quite consistent in cropssuch as sorghum (Sorghum bicolor), pearlmillet (Pennisetum americanum) and fingermillet (Eleusine coracana). Azospirillum species inoculation can contribute 20–40 N/ha, resulting in an increase of crop yield by 10%–15%. The yield increase up to 11% in many crops has been reported (Wani, 1992). Despite their nitrogen-fixing capability, the increase in yield caused by Azospirillum inoculation is mainly attributed to an improvement in root development by the production of plant growth–promoting substances, such as auxins, cytokinins, and gibberellins. After inoculation onto plant roots, Azospirillum cells induce remarkable changes in the morphology and behavior of the entire root system. Hairs close to the root tip take on a more distinctive appearance, and the overall density and the length of the root system increase. Root hairs consist of expanded root epidermal cells, which play a role in water and nutrient exchanges and also help to anchor root to its surroundings. It also increases the diameter and length of both lateral and adventitious roots and thereby leads to additional branching of the lateral roots. These developments in the root system in turn increase absorptive area and volume of the soil substrate available to the plant, thereby resulting in increased uptake of soil nutrients. Like Azotobacter, it can also be used for treatment of seeds or seedlings. Another bacterium Herbaspirillum, which is taxonomically very closely related to Azospirillum, has also been found to be associated with grasses and contributes for nitrogen.
Plant Nutrition and Turf Fertilizers
Published in L.B. (Bert) McCarty, Golf Turf Management, 2018
Roots are the principal means by which nutrients and water enter plants. The root system is usually very large and extensive, allowing plants to make contact with a tremendous volume of soil. Root hairs greatly increase the surface area of roots and are the principal site of nutrient and water uptake.
Effects of arsenite on physiological, biochemical and grain yield attributes of quinoa (Chenopodium quinoa Willd.): implications for phytoremediation and health risk assessment
Published in International Journal of Phytoremediation, 2021
Arslan Shabbir, Ghulam Abbas, Saeed Ahmad Asad, Hina Razzaq, Muhammad Anwar-ul-Haq, Muhammad Amjad
Results from the current investigation revealed that As significantly influenced the growth and yield of quinoa plants. Experimental plants exposed to higher concentrations of As (30 and 40 mg As) could not survive until maturity, perhaps because of As induced phytotoxicity, and with the initiation of permanent wilting (6 weeks after germination). Toxic effects of As on plants are extensively reported (Tripathi et al. 2017; Alam et al. 2019; Parvez et al. 2020). In these studies, As rendered detrimental effects on the growth and yield of several food crops. Pronounced reductions in plant growth under As stress may be attributed to nutrient imbalance, impairment of root hair formation, alterations in enzymatic activity, and inhibition of chlorophyll biosynthesis resulting in reduced biomass accumulation, stunted growth and ultimately compromised crop yield (Sharma 2012).
Promises and potential of in situ nano-phytoremediation strategy to mycorrhizo-remediate heavy metal contaminated soils using non-food bioenergy crops (Vetiver zizinoides & Cannabis sativa)
Published in International Journal of Phytoremediation, 2020
Roots of most of the plants, including fruits trees, ornamentals, cereals, vegetables, forest trees and shrubs, etc., growing naturally in undisturbed soils around the world, often form symbiotic relationships with arbuscular mycorrhizal (AM) fungi. In the past, there has been considerable interest in the potential use of AM fungi in agricultural and forestry practices but neglect of their importance in disturbed and contaminated derelict lands (Hayes et al.2003; Khan 2007). Most of these plants have a strong dependency on these universal MF for optimal growth, even under stressed conditions. Symbiosis of the plant root system with these universal mycorrhizal fungi can provide additional stimulus by improving soil fertility (Pal and Pandey 2014), to meet the challenges of increasing plant productivity, stress tolerance, and health. To improve plant health and increase biomass for enhanced phytoremediation potential and efficiency of bioenergy fast growing plants, and to overcome several phytoremediation limitations, such as low biomass and low bioavailability of contaminants, we need to consider the potential of AMF and associated PGPR microbiota in our efforts to phytoremediate contaminated and derelict lands (Khan 2020). All ecosystems, including agricultural as well as contaminated degraded ones, have in situ soil microbial communities’ integral components of which are VA mycorrhizal fungi and their propagules, which regulate nutrient transfer between plants and their rhizospheres via external mycelial hyphae. The mycorrhizal symbiosis is a key stone to the productivity and diversity of natural plant ecosystems, as the extrametrical fungal hyphae of AMF produce glomalin-related, water soluble, and resistant to decay soils protein components, i.e., nano-molecules, in large amounts, which as a stable glue, binds to soil, producing aggregate structures composed of minerals, including HMs, and humus (Yadav 2014). Increased organic matter increases cation exchange capacity of soils (Andrade et al.1998; Wang et al.2017; Pare et al.2019). These aggregates permit the soil to retain water better and facilitate root penetration. Furthermore, these aggregates not only reduce soil erosion but also help root-hair adhesion, enhancing nutrient and water uptake. Multiple interactions and feed backs take place in the root rhizosphere between roots, soil fauna, and various inorganic binding agents, which influence aggregate formation and stabilization (Khan 2008; Pal and Panday 2014) (Figure 5).