Yield and water use efficiency assessment of roselle (Hibiscus sabdariffa L.) as affected by nutritional different resources and regimes of irrigation water

Introduction Roselle is an annual plant, Short day, self-pollinated and in terms of weather conditions is sensitive to cold and frost stress (Duke, 2006). Evaluation of water use efficiency is a way to study the water management and its relative values it is appropriate to compare the different crops. Water use efficiency is the amount of dry material produced per unit of water and it is usually expressed in kilograms of dry material per cubic meter of water. Severe restriction of water and high costs for water supply and transfer causes that in some cases or regions from an economic perspective, the optimal level of irrigation is less than the required amount to produce maximum yield. The proper management of irrigation and planting for drought resistant plants (Ston and Nofziger, 1993). Due to the beneficial effects of organic and biological fertilizers in agricultural ecosystems, increased vegetative growth, yield components and sepal yield in Abelmoschus esculentus L. (Tiamiyu et al., 2012), Hibiscus cannabinus L. (Basri et al., 2013), Borago officinalis L. (Naghdi Badi et al., 2011; Ahmadabadi et al., 2011), Hibiscus sabdariffa L. (Gendy et al., 2012; Dahmardeh, 2012) have been reported. Nowadays, the cultivation of drought resistant plants has been proposed as a strategy against drought. Roselle is one of the low water requirement and drought resistant, in Southern Iran, which is facing a shortage of irrigation water can be used as a suitable plant in cropping pattern. This research was conducted in Jiroft with the aim of studying the effect of fertilizer resources and different levels of irrigation on yield and water use efficiency of Roselle medicinal plant. Material and methods A field experiment was conducted at the experiment station of Faculty of Agriculture, University of Jiroft (latitude: 28°40´ N; longitude: 57°44´ E; elevation: 650 m) during 2013 and 2014 growing season. Experimental site was located in southeast of Iran Kerman Province, Jiroft county. The climate of the area is arid and semiarid. A strip plot based on a randomized complete blocks design with three replications was used. Horizontal factor were irrigation regimes at threelevels of 100%, 80% and 60% ofcrop water requirement and fertilizer resourceswere fertilizer resourceswere mycorrhiza, vermicompost, cow manure, chemical fertilizer (NPK) and controlas vertical factor. Plant water requirement is calculated by AGWAT software (Alizadeh and Kamali, 2008). The evaluated traits included number of bolls per plant, sepal dry weight per plant, 100 seed weight, sepal yield, seed yield, biomass yield, sepal water use effeicency, seed water use effeicency and biomass water use effeicency. Harvesting the plant was done on December 1, 2013 in the first year and December 1, 2014 in the second year. Results The average number of bolls showed that the higher number of bolls and weight of dried sepal in irrigation levels of 100% and 80% of plant water requirement in terms of cow manure and vermicompost and the lowest of them in irrigation levels of 60% plant water requirement were belonged to control and mycorrhizal treatments, respectively. Sepal yield at all three levels of irrigation showed increase in the plants treated with manure, vermicompost and chemical compared with mycorrhizal and control treatment and sepal yield in the second year than the first year was higher. The highest seed yield and biomass yield was related to cow manure, vermicompost and chemical fertilizers that was observed in irrigation level of 100% and then 80% water requirement and the lowest of it was belonged to control and mycorrhizal treatment and irrigation level of 60%, respectively. During the two years study, sepal water use efficiency in the second year with the amount of 116.90 g.m-2 of water was significantly higher than the first year with the amount of 102.99 g.m-³. The average comparison in result of applying different levels of irrigation showed that the highest and lowest levels of seed water use efficiency was observed in 60% irrigation treatment and irrigation level of 100%. Rezapour et al (2011), by investigating the effect of drought stress and different amounts of sulfur fertilizer on Nigella sativa L. Similar results observedin Roselle (Hibiscus sabdariffa L.) (Gendy et al., 2012; Dahmardeh, 2012), and Okra (Abelmoschus esculentus L.) (Tiamiyu et al., 2012). Conclusion Based on two years data combined analysis, the results indicated that fertilizer resources and irrigation regimes had significant effect on the most morphological and agricultural traits. The interaction effect of fertilizer resources and irrigation regimes had a significant effect on calyx yield, 100 seed weight and sepal water use efficiency . The highest calyx yield (1248 kg.ha-1) was obtained at 100% crop water requirement cow manure treatment and the lowest calyx yield (510 kg.ha-1) was obtained at 60% crop water requirement control treatments. According to the results, it can be concluded that 80% crop water requirement treatment with the use of cow manure, vermicompost and chemical fertilizer are desirable treatments in roselle production.