Studying the effect of no irrigation on grain yield and physiological characteristics of corn (Zea mays L., S.C.704) in summer planting

Introduction Drought is one of the most important risks to crop growth. Corn is plant with spring growth and its production in our country that summer rain is lacking, depends heavily on irrigation water. Any change in irrigation time in each period of growth causes problems on yield. Delay in irrigation that does not damage the performance depends on growth stage, stress duration, air temperature, soil texture and the type of hybrid. Accordingly, this experiment was conducted to investigate the possibility of removing some of the irrigation steps or reducing irrigation water levels at some stages of development, leading to the least yield loss. Materials and methods In order to evaluate the effect cutting of irrigation at different times of growth on yield and yield components and some physiological traits of corn (SC704) carried out a research in a randomized complete block design (RCBD) with three replications in the village of Ciahgol, Gilangharb (tropical region), Kermanshah, Iran, in summer 2015. Treatments including control (irrigation each week) and no irrigation (NI) for two weeks (from 7, 21, 35, 49, 63, 72 and 91 days after planting) and no irrigation (NI) for three weeks (from 7 , 28, 49, 70 and 91 days after planting). In all treatments was delayed only once irrigation for two or three weeks and before and after the no irrigation treatments was done each week. Soil text was clay-loam. Each plot including 5 rows × 6 meter length. Plant density was 85000 plants per hectare. In this experiment were measured economic yield, biological yield, water use efficiency, plant height, chlorophyll a, b and total, proline, kernels traits and ear. Finally, data analyzed by SAS software and means compared with LSD test. Results and discussion The results of analysis of variance showed that NI for 3 weeks cause decreased grain yield, 1000-kernel weight, plant height, water use efficiency of biological and economic, chlorophyll a, chlorophyll b and increased proline. Maximum of grain yield (13600 kg ha-1) and 1000-kernel weight (232 g) obtained at control treatment and at 3 weeks NI from 49 days after sowing (tassel emergence), were 0.0 and 0.0 kg ha-1, respectively. Grain yield reductions in most treatments were due to the decrease in the number of rows, number of kernels per row and 1000-seed weight. Biomass yield at this treatment of stress decreased about 66 percent compared to control. Thousand grain weights at control treatment and two weeks NI from 7 days after of sowing had the highest amount (232 g) and the lowest was at 3 weeks NI and 70 days after sowing (220 g). The highest and lowest number of kernels per row was in control (50) and three weeks in the treatment of NI from 49 days after sowing was zero. Treatment two weeks of stress from 7 days after sowing had the maximum number of rows per ear (14.9). The highest number of grains per ear was two weeks in the treatment of NI from 7 days after sowing (732.1) and the lowest total grains per ear in the treatment of 11 (zero). With increasing drought duration (two weeks to three weeks) at the beginning of the emergence of male inflorescence reduced number of seed per row, So that was two weeks in the treatment of NI from 49 days (15.1) and at 49 days of treatment three weeks of stress (zero). Control had the highest plant height (206 cm). The lowest of plant height was at three weeks of treatment 28 days after sowing (123 cm) that decline of about 40 percent Compared to control. Conclusions However, results showed that early and late stages of corn growth had the lowest susceptive and the most resistance were anthesis and grain filling period according as no irrigation for two weeks cause decreased significant in grain yield. Acknowledgements We thank all of friends that help us. This work was supported by the Razi University, Campus of Agriculture and Natural Resources.