effect of deficit irrigation treatments on morphological traits and growth indices of corn forage in the rasht climate

in order to study of effects of deficit irrigation on morphological traits and growth indices variation of corn forage (sc. 704) in rasht region, an experiment based on randomized complete design with four treatments and three replication was conducted in 2007 growing season, at research farm of faculty of agriculture, university of guilan. experimental treatments consisted of: no-irrigation, 100%, 75% and 50% (full irrigation) available water depletion from soil. results showed that irrigation based on 75% available water depletion from soil caused significant reduction in leaf dry matter, crop growth rate and leaf area index. in comparison with full irrigation and 75% available water depletion from soil, 100% available water depletion from soil caused significant reduction in total dry matter, ear, stem and leaf dry weight, leaf area index, crop growth rate, leaf number and plant height. in the non-irrigation and 100% available water depletion treatments the total dry matter, stem dry weight, ear dry weight, leaf number, flowering duration and plant height significant difference not seen. with reduction in irrigation water, silking and ear formation delayed and stem diameter increased. deficit irrigation increased water productivity and 75% available water treatment was showed a better performance (6.07 kg.m-3). forage dry matter in 50%, 75% and 100% available water depletion and non-irrigation was 16191.25, 14563.56, 11479.51 and 10879.83 kg.ha-1, respectively. according to the results, in rasht region climate, after 75% available water depletion from soil, growth indices significantly varied. thus, in this region, irrigation based on 75% available water depletion from soil may cause improvement in corn forage.