Impact of foliar application of humic acid and the measure time on growth and production of roselle Hibiscus sabdariffa L.

Abstract

The present study was accomplished to achieve the effect of Humic Acid (HA) spraying on the vegetative and calyxes yield characteristics of Hibiscus sabdariffa L. plants, during May ,22th to December, 31st, 2017, at (Girdarasha) open field, Department of Horticulture, Agricultural Engineering Science College, Salahaddin University. Four levels of HA were sprayed (0, 1, 2, 3 g.l-1) at three frequencies (60, 75 and 90 days after sowing). The data were collected after (4, 8 and 12 weeks of last spraying) for vegetative and reproductive parameters: plant height (cm), number of branches, stem diameter (mm), days to 50% of plants flowering, flower diameter (mm), node sequence of 1st flower, number of fruits. plant-1 , fruit length (mm), fruit diameter (mm), fresh and dry weight of fruits. plant-1 (g) and fresh weight of calyxes. plant-1 (g). The obtained results revealed that all treatments of HA increased significantly both vegetative and reproductive parameters and shortened the number of days to flowering as compared with the control. The application of 2g.l-1 produced the tallest plants. Maximum numbers of branches were obtained from the treatment 3g.l-1 HA. The 2g.l-1 and 3g.l-1 treatments formed the thickest stems. Regarding the reproductive parameters; the highest values of fruit diameter, fruit length, fresh and dry weights of fruits. plant-1, fresh and dry weights of calyxes.plant-1 were recorded with the treatment 3g.l-1 after 8 weeks of the last treatment.