effect of super-absorbent, manure and irrigation frequency on growth and some physiological and biochemical characteristics of rose geranium

this research was carried out to evaluate the effect of super-absorbent and manure on growth, yield, physiological and biochemical characteristics of geranium under deficit irrigation at research greenhouse of faculty of agriculture, lorestan university, iran, in 2014. the experiment was arranged factorially based on a completely randomized design with six replications. factor a was substrate consisted of control, 1 and 2 percent super-absorbent, or 25 percent manure and factor b was irrigation with 3, 5 or 7 d interval. the results showed that as irrigation frequency decreased, plant growth and oil yield decreased and oil content, malondialdehyde, proline, peroxidase and ascorbate peroxidase increased. both manure and super-absorbent improved plant growth, physiological and biochemical characteristics under deficit irrigation. however, the effects of manure were more pronounced, so that the values for most characteristics, like, leaf area, plant fresh and dry weight and oil content of plants grown in substrate including manure irrigated with 7d interval were the same as those of control plants irrigated with 3d interval. the highest water use efficiency for oil production was found in plants grown in substrate including manure in all irrigation frequencies as well as plants grown in substrate including two percent super-absorbent irrigated with 7d interval.  according to these results and due to abundance, cheapness and environmental sustainability, using 25 percent in volume manure in substrate could be recommended to increase water use efficiency.