Management of cutting height and nitrogen fertilizer rates on grain yield and several attributes of ratoon rice (Oryza sativa L.) in Iran.

In order to study effects of cutting height and nitrogen fertilizer rates on yield and several attributes of ratoon rice an experiment in factorial format based on randomized complete block design with three replications in Rasht township (north of Iran) during 2009 farming year was conducted. Factors of experiment were included three levels of cutting height (H :10 cm, H :25 cm and H :30 cm cutting height) and four levels 12 3 of nitrogen fertilizer rates (N : control (without nitrogen fertilizer application), N : 30 kg/ha, N : 60 kg/ha and 1 23 N : 90 kg/ha nitrogen fertilizer). Studied traits were grain yield, number of tillers per plant, number of grains per 4 panicle, plant height and 1000 grains weight. Results of experiment showed that, the effect of cutting height on grain yield in 1% and on number of tillers per plant in 5% probability level was significant and on other traits was non significant. Effect of nitrogen fertilizer on grain yield and number of tillers per plant in 1% and on plant height in 5% was significant. But on number of grains per panicle and 1000 grains weight doesn't showed significant differences. Interaction effects between cutting height and nitrogen rates on grain yield showed significant differences in 1% probability level and on other traits was non significant. Eventually, the highest grain yield with 1952 kg/ha was recorded from 30 cm cutting height along with 60 kg/ha nitrogen fertilizer application (H N treatment). 33