Progênies de algodoeiro tolerantes ao estresse hídrico

Abstract

Due to the low rainfall and prolonged periods of drought in the semi-arid regions of Brazil, cotton production is compromised, especially when cultivated under rainfed regimes. In this sense, the present work aims to evaluate the performance of 20 cotton hybrids cultivated under water deficit. Nine cotton cultivars were used to obtain the following hybrid combinations: FMT 705 x CNPA ITA 90; FMT 705 x CNPA 5M; FMT 705 x CNPA 7MH; FMT 705 x BRS Seridó; FM 966 x CNPA ITA 90; FM 966 x CNPA 5M; FM 966 x CNPA 7MH; FM 966 x BRS Seridó; BRS RUBI x CNPA ITA 90; BRS RUBI x CNPA 5M; BRS RUBI x CNPA 7MH; BRS RUBI x BRS Seridó; BRS 286 x CNPA ITA 90; BRS 286 x CNPA 5M; BRS 286 x CNPA 7MH; BRS 286 x BRS Seridó; BRS 701 x CNPA ITA 90; BRS 701 x CNPA 5M; BRS 701 x CNPA 7MH; BRS 701 x BRS Seridó. The experiment was carried out in the experimental field of Embrapa Algodão in Barbalha, CE. The experimental unit consisted of 2 rows of 5m in length, with a spacing of 0.90m x 0.20m, with a population density of 70 plants per plot and experimental design in randomized blocks. The variables analyzed were: plant height, seed cotton yield, fiber percentage, boll weight, fiber length, fiber uniformity, short fiber index, strength, elongation at break, micronaire index and reliability index. Statistical analyzes were performed using the GENES program, version 1990.2017.46 (Cruz, 2013). The analysis of variance was carried out using the F test to verify the variability between the materials and the Scott and Knott test was applied for the grouping analysis of means. For the correlation analysis, the Pearson correlation test was applied and the Mulamba and Mock (1978) index was used to classify the materials that obtained the best performances and to estimate the genetic gain. The evaluated characters have a high coefficient of genetic determination for all characters. The variables %FIB, length, reliability index and uniformity obtained the best averages for all hybrids under stress condition. The greatest selection gains were observed for the variables: weight of a boll (10.12%) and productivity (8.11%). According to Mulamba and Mock (1978)’index, the selected progenies were: BRS 286 x BRS Seridó; FMT 705 x CNPA 7MH; FM 966 x BRS Seridó and FMT 705 x BRS Seridó. Such combinations presented positive and promising perspectives in the scope of cotton genetic improvement for the semiarid region and for the development of new lines/cultivars.