Effect of organic and inorganic fertilization with spraying of fulvic acid on nutrients uptake, quality and yield of roselle (Hibiscus sabdariffa L.)‎ plant grown in sandy soil at Siwa Oasis, Egypt

Abstract EN

During two successive seasons (2016 and 2017) at Khimisah experimental farm which is located at the latitude of 29°12' 34.5 N'', and the longitude of 25° 24' 2.56'' E., Siwa Research Station, (Matrouh Governorate), Desert Research Center, Egypt, a field experiment was executed under irrigation with saline water (4.2dSm-1) to investigate the effect of five fertilizer combinations (FC) of both organic and inorganic fertilization as follows; 100 %NPK recommended dose i.e.

180kgN, 31kgP and 100kgK ha-1 (FC1), 50%NPK+6MT compost ha-1 (FC2), 75 %NPK+ 6MTha-1 compost (FC3), 50 %NPK + 12MTcompost ha-1 (FC4) and 75%NPK + 12 MTcompost ha-1 (FC5) and foliar application of fulvic acid at four levels i.e.

0.0, 250, 500 and 750mgL-1 on the vegetative growth parameters, leaf nutrient uptake, yield and quality of roselle (Hibiscus sabdariffa L.) plants in arandomized complete block design with split plot technique in three replications where the main factor was five fertilizer combinations (FC) while the sub main factor was the foliar application of fulvic acid treatments (FA).

Results indicated that the single application of FC5 or FA (at 750mgL-1) showed the highest significant values for plant height (cm), leaves number/plant, leaves dry weight g/plant, branches number/plant, branches fresh weight g/plant and branches dry weight /plant, leaf N, P, K, Fe, Zn and Mn uptake, sepals yield MTha-1, seed yield MTha-1, seed fixed oil yield Lha-1, sepals anthocyanin, vitamin C and acidity in both study seasons.

The dual application of FC5 with FA at 750mgL-1 resulted in increasing in all studied parameters except sepals acidity which are reduced in both study seasons.

It can be concluded that the dual application of FC5 with FA at 750mgL-1 is considered as a recommended treatment in the cultivation of roselle plants at Siwa Oasis due to it resulted in high yield and quality and the highest net profit (40.450×103ha-1 ) and the highest net return (29.336×103ha-1) and reducing theenvironmental pollution because of it had partial replacement of mineral fertilizer with organic one (compost and fulvic), especially under the conditions of Siwa Oasis as a natural reserve.