Response of Cotton Growth and Yield to Foliar Application With the Growth Regulators Indole Acetic Acid (Iaa) and Kinetin

Abstract

Two field experiments were carried out at Sids Agric. Res. Station, Beni-Suef Governorate, in 2007 and 2008 seasons, to study response of growth, fruiting and yield of the Egyptian cotton cultivar Giza 80 (G. barbadense L.) to foliar application with indole acetic acid (IAA) and Kinetin (a synthetic cytokinin). Besides the control treatment, two concentrations of each of IAA (25 and 50 ppm) and kinetin (10 and 20 ppm) and their combinations were application twice, at the start and peak of flowering stages. Results revealed that, cotton plants treated with various treatments of IAA and/or kinetin showed higher leaves content of chlorophyll a, b and total chlorophylls than those of untreated ones. However, only some treatments of IAA and/or kinetin significantly increased plant height, numbers of fruiting branches/plant and open bolls/plant in both seasons; number of main stem nodes and seed cotton yield/fad., in 2007 season only; and total fruiting sites/plant and seed index in 2008 season only, but they significantly decreased fruit shedding% and earliness% in 2007 season only. Application 50 ppm IAA alone significantly decreased earliness% in 2007 season, and either alone or with kinetin at both levels gave the highest values of plant growth parameters, but their effects on fruit shedding and yield did not reach the significant level. In general, the most consistently positive effects on plant fruiting and seed cotton yield were given by application 25 ppm IAA alone or 20 ppm kinetin alone or both.

Effect of Plant Distribution Patterns and Growth Regulators on Morphological, Yield and Technological Characters of Egyptian Cotton

“…In addition, MC is an anti-gibberellin that inhibits the production of gibberellins in the plants which normally would enlarge the plants cells by blocking the cyclization of geranylgeranyl pyrophosphate to capatyl pyrophosphate and also blocks further trans of capatyl pyrophosphate to ent-kaurene in the gibberellic acid biosynthesis pathway. Similar results were obtained by other investigators who found that foliar application of growth regulators such as kinetin at a rate of 20 ppm (Kassem et al, 2009), NAA at a rate of 30 ppm (Kataria andKhanpara, 2011 andSabale et al, 2017) significantly increased plant height compared to untreated plants. However, Priyanka and Dalvi (2019) reported that application of MC decreased plant height.…”

“…When stimulators growth regulators are applied to young fruits, there is a stimulation in growth and a retardation of abscission by delaying leaf senescence. In this regard, other researchers reported that number of squares/plant was increased by application of 1 ml MC/L (Abdel-Aal et al, 2011) and kinetin at 20 ppm (Kassem et al, 2009). Moreover, number of bolls/plant was increased by the application of NAA (Parveen et al, 2017) and MC (Priyanka andDalvi., 2019 andHussain et al, 2021).…”

“…The increase in earliness % obtained by NAA could be a resulted of its enhancing effect on translocation and utilization of photosynthetic metabolic product and consequently might stimulated physiological maturity. Foliar application of growth regulators such as NAA (Parveen et al, 2017), kinetin (Kassem et al, 2009) significantly enhanced earliness percentage of cotton compared to control.…”

“…In this respect, leaf area/plant was increased by the application of NAA at rate of 0.045g/100 L (Parveen et al, 2017). Chlorophyll content was significantly increased by foliar application of growth regulators such as NAA (Parveen et al, 2017), MC (Sabale et al 2017) and kinetin (Kassem et al, 2009) compared to untreated cotton plants. Moreover, Sarlach and Sharma (2012) stated that application of NAA at rate of 20 µg/ml increased stem, leaves and total dry weights/plant compared to untreated plants.…”

“…Most growth retardants act by inhibiting gibberellin (GA) biosynthesis. It is quite apparent that application of growth regulators could increase cotton productivity (Kassem et al, 2009, Abdel-Aal et al, 2011and Parveen et al, 2017 and improve fiber quality (Echer and Rosolem, 2017) as well as seed quality (Zohaib et al, 2018).…”