Effect of different levels of potassium fertilizer and irrigation water on physiological characteristics and yield plant of roselle

Today, changing the pattern of planting towards water deficit resistant plants is proposed as a solution to drought. One of the plants resistant to drought is roselle. In this study, the effect of different levels of irrigation water and potassium fertilizer on roselle was investigated. Experiment with split plot design with four levels of irrigation water (I1, I2, I3 and I4 equivalent to 40, 60, 80 and 100% water requirement) three levels of potassium (K1, K2 and K3 equivalent 50, 75 and 100% potassium requirement) as sub-plot. At the end of experiment, parameters of dry yield and irrigation water productivity and Qualitative parameters of anthocyanins, proline, carotenoids, chlorophyll a, chlorophyll b and carbohydrates were measured. The results showed that the simple effects of irrigation water and potassium fertilizer were significant (P <0.01) on all measured parameters. The highest yield was obtained from 100% potassium fertilizer treatments and 80% water requirement. The highest irrigation water productivity was obtained in 60% water requirement and 100% potassium fertilizer application but no significant difference was found between 60 and 80% water requirement. In terms of quality, the amount of anthocyanins, carbohydrates and proline increased with decreasing the depth of irrigation water to 60% of the plant's water requirement and reducing the consumption of potassium fertilizer, and the amounts of chlorophyll a and b and carotenoids decreased. However, there was no significant difference between 50 and 75% K fertilizer application. Therefore, due to the water status of the region and the reduction of water resources, 80% water requirement reduces water consumption and 75% potassium fertilizer increases quality and mitigates drought stress in roselle. Also, due to the dry climatic conditions of Sistan region, the use of potassium fertilizer can reduce the damage caused by drought stress in roselle.