• Dr. Md. Mamunur Rashid

Plant growth regulators (PGRs) are exogenously applied chemical compounds that regulate stem elongation through inhibiting biosynthesis of gibberellins or releasing ethylene. PGRs have been and are still mainly used in modern, high input cereal management to shorten straw and thereby increase lodging resistance. There are indications that PGRs have potential to modify cereal yield formation and plant stand structure additional to stem elongation. Often these changes occur through changes that mimic similar responses to those attributable to day length. The principal interest in this publication was to evaluate the possibilities of applying some commonly used PGRs to modify cereal growth and formation and realization of yield potential under Finnish, long day growing conditions. As PGR response may vary depending on plant height, the response of all crops was evaluated to understand better crop production. PGR effect on assimilate distribution within main shoots and tillers as well as to roots was monitored. Potential PGR induced stress-effect in treated plants was monitored by measuring post-treatment ethylene production rates from the roots and shoots and measuring carbon dioxide change rate (CER) of PGR treated and control plants. Application of PGRs at recommended times generally reduced stem elongation. When applied during early growth stages, PGRs failed to reduce canopy height measured at maturity. However, when shoot elongation was measured 14 days after early PGR application, main shoot elongation of all species and cultivars was reduced, indicating similar responsiveness to PGRs at early growth stages, independent of PGR or genotype. PGRs did not change markedly photo-assimilate distribution or translocation pattern in studied cultivars. Tillering was slightly increased by early PGR applications, but the effect was only temporary and at maturity no PGR effect on tiller number was recorded. Root growth, in terms of elongation or dry-weight accumulation, was not improved by PGRs. According to results of ethylene evolution and photosynthesis measurements, PGRs do not appear to induce marked stress in treated plants, or at least not a stress associated with elevated ethylene production or markedly reduced CER. Both yield increases and decreases followed PGR applications. Changes in grain yield were associated with changes in single grain weight or in grain number per head. Due to variable yield responses following PGR applications in the absence of lodging pressure, no general recommendations can be given and careful consideration is needed when selecting a PGR for a specific cultivar.

Plant growth regulators, Auxin, Gibberelin, Cytokinin, Crops, Development

"A Documentary Review on Plant Growth Regulators", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.9, Issue 2, page no.b492-b501, February-2022, Available :http://www.jetir.org/papers/JETIR2202157.pdf

"A Documentary Review on Plant Growth Regulators", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.9, Issue 2, page no. ppb492-b501, February-2022, Available at : http://www.jetir.org/papers/JETIR2202157.pdf