Effect of irrigation disruption and biological nitrogen on growth and flower yield in Calendula officinalis L.
To evaluate the effect of irrigation disruption and biological nitrogen on growth and yield of in Calendula officinalis L., an experiment was conducted as split plot at the research farm of Faculty of Agriculture of Urmia University (latitude 37.53°N, 45.08°E, and 1320 m above sea level), Urmia-Iran in 2010. Treatments including irrigation (irrigation disruption at first, second, third harvest and without disruption as control) as main plot and amount of biological nitrogen (0, 3, 6 and 9 L/ha of nitroxin) as sub plots were arranged in randomized complete block design, with three replications. Results show the significant effect of irrigation disruption on the stem weight and of biological nitrogen on the stem weight and capitulate diameter. Interaction effect between irrigation and biological nitrogen was significant on the leaf weight, stem length, the number of sub stem, biomass, and seed yield, and harvest index of seed. The highest biomass (1298.5 g/m2) and seed yield (68.83 g/m2) were obtained
from irrigation disruption at second and third harvest with 6 and 9 L/ha of nitroxin application, respectively. In addition, the maximum (4.29 %) harvest index was obtained from irrigation disruption at third and second harvest with 9 L/ha of nitroxin application. In conclusion, lower amounts of nitrogen was needed to produced the optimal yield of seed in water deficit situation compared with non stress condition, while the nitrogen needed to produce the biomass was in higher amounts.
Key words: Calendula officinalis, capitulate, nitroxin, water stress, yield.