Response of different Bt cotton (Gossypium hirsutum L.) hybrids to canopy modification practices

Abstract

A field investigation was carried out to characterize the growth and development of Bt cotton hybrids by detopping and use of plant growth retardants during the rainy (kharif) season of 2011 and 2012. The experimental site had loamy sand soils with normal in reaction. The experiment (split plot) involved three Bt cotton hybrids (MRC 7017, MRC 7031 and RCH 314) in main plots and growth regulation treatments (Mepiquat chloride (MC) @ 300 ppm, 2, 3, 5-tri iodo benzoic acid (TIBA) @ 100 ppm and Maelic hydrazide (MH) @ 250 ppm) in sub plots with four replications. Hybrid MRC 7017 produced significantly higher (p<0.01) seed cotton yield which was attributed to the maximum number of sympodial branches plant-1, total number of flowers and picked bolls plant-1. Application of MC @ 300 ppm, TIBA @ 100 ppm and MH @ 250 ppm reduced plant height, leaf area index and total dry matter accu-mulation than control. Detopping treatment significantly (p<0.01) reduced plant height than control but attained more plant height than all the PGRs. MC @ 300 ppm, TIBA @ 100 ppm and MH @ 250 ppm at 80 days after sowing had beneficial effect on seed cotton yield. Detopping done at 80 days after sowing failed to influence the seed cotton yield dur-ing both the years. The results revealed that foliar application of MC @ 300 ppm yielded more seed cotton by improv-ing the setting percentage and therefore, increased number of picked (open) bolls plant-1 without exhibiting any ad-verse effect on quality traits.

Effect of Different Doses and Scheduling Time of Plant Growth Regulators and Defoliants on Growth and Yield of Cotton (Gossypium hirsutum L.) under High Density Planting System

“…At harvest control treatment was superior (5988 kg ha -1 ) out performed other treatments in drymatter accumulation and lowest figure was recorded with the application of M.C 20, 25, 30 g a.i ha -1 @ 40, 55 & 70 DAE respectively + Ethereal 2000 ppm @ 40% boll burst (T9) (4220 kg ha -1 ). Similar findings were noted by Priyanka et al [12], Kaul et al [20] and Paslawar et al [21]. The decrease in the accumulation of drymatter production could be because of both the observed decline in plant height and the disruption in the source sink relationship resulting from the application of Mepiquat chloride Priyanka et al [12].…”

Effect of Transplanting Cotton on Growth, Earliness, Productivity and Fiber Quality As Compared with Early and Late Direct Seeding Under Spraying with Pix تأثير شتل القطن على النمو والتبکير و الإنتاجية وجودة التيلة مقارنة بالزراعة المبکرة والمتأخرة بالبذرة تحت الرش الورقى بالبکس

“…IV. Altering dry matter distribution pattern and/or regulating the growth attributes in crop plants (Kaul et al, 2016;Yakubu et al, 2018 andEl-Shazly, 2020).…”