What are the PGR for root system?
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Answer:
Phytohormones or plant growth regulators play a significant role in the growth, development, and distribution of essential nutrients in plant systems, but the fluctuating environmental conditions force the employment of several hormonal modifications in plants to adapt to the changing environment. The presence of several nanomaterials like CNTs in soil stimulates and enhances the endogenous levels of phytohormones in plants (Rui et al., 2016). Several prominent phytohormones present in plants like indole-3-acetic acid (which is mainly responsible for various physiological processes such as cell elongation and division, and a defense mechanism by the expression of several genes under biotic and abiotic stress) (Song et al., 2014), and steroidal hormones such as brassinolide (which regulates growth and developmental processes and provides resistance against biotic and abiotic stresses such as cold stress and pathogen infection) (Haubrick et al., 2006; Vriet et al., 2013), gibberellins (which regulate growth and influence various developmental processes, including stem elongation, seed germination and dormancy, flowering, leaf expansion, sex expression, enzyme induction, and leaf and fruit senescence) (Rodrigues et al., 2012; Muhammad and Muhammad, 2013), and cytokinins (isopentenyladenine, which regulates several important metabolic reactions in plants) (Ma, 2008) in the presence of several types of CNTs in a soil environment upsurge the endogenous concentration of phytohormones (Mastronardi et al., 2015). Several studies have been conducted that display similar results and show that exposure of CNTs at higher expanse amplified the phytohormones level in rice shoots and exerted several positive effects like elongation of root and shoot length; similar reports for several plants like S. lycopersicum, Triticum aestivum, Glycine max, Z. mays, Brassica juncea, and Phaseolus mungo (Khodakovskaya et al., 2009; Ghodake et al., 2010) have been suggested. Several studies testified that CNTs at lesser doses stimulate the growth pattern in plants, whereas they inhibit growth and cause toxicity in plants at higher amounts by induction of the formation of reactive oxygen species, which generate oxidative stress, in turn damaging the membrane because a resultant electrolyte leakage takes place and these reactive oxygen species lead to DNA aberration as well as cell death. Apart from enhancing plant growth, the effects of CNTs have also been explored at the reproductive stages of plant development.
A study has been reported by Khodakovskaya et al. (2011) that shows the doubling of flower setting and yield in tomato (S. lycopersicum), grown along with CNTs, which was not visualized in control plants. CNTs also bring modification in morphological traits in plants and these changes are often concomitant with changes in gene expression and DNA damage, including alteration in chromatin structures. They also act as stress factors with the ability to initiate plant defense responses and trigger overexpression of certain stress-related genes, such as subtilisin-like endoprotease, meloidogyne-induced giant cell protein, and threonine deaminase. Similarly, Villagarcia et al. (2012) reported increased expression of aquaporin (water channel protein) seedlings of S. lycopersicum. Please mark the answer as the branliest
Answer:
crops tested included: Hemerocallis ‘Pink Song’, Penstemon digitalis ‘Husker Red’, Phlox paniculata ‘David’, and Lobelia cardinalis.
Concise applications included: liner soaks (2 min) the before potting; foliar sprays at label recommended volume of 1 gallon per 200 square feet; or substrate drench applied at 2 fluid ounces per quart plastic pot. Sprays and drenches were applied about 2 weeks after potting.
Plants were harvested weekly for shoot and root dry weights and the root to shoot dry weight ratio was calculated. Higher root:shoot ratios have been correlated with faster plant establishment in the field.