Study the effect of irrigation termination at different growth stages of corn on content and amount of grain’s elements

The shortage of water during the growth period of the maize plant causes damage to the growth stage that depends on type of hybrid, the geographical location, the weather conditions and the soil. Because at different growth stages, maize is in different condition in terms of development and root growth, electrical conductivity, drought tolerance and shoot growth. Therefore, water shortages at each stage of growth may lead to changes in the absorption of mineral elements, the production of materials or transfer to a reservoir, which ultimately affects the quality of the grain.

In order to evaluate the effect not irrigation at different times of growth on the amount of elements in the grain 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 not irrigation (NI) for two weeks (from 7, 21, 35, 49, 63, 77 and 91 days after planting) and not 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. Sowing date was 27 June, 2015. Soil text was clay-loam. Each plot including 5 rows × 6 meter length. Plant density was 85000 plants ha-1. In this experiment, the traits of concentration and yield of the elements in the grain were measured including iron, zinc, copper, nitrogen, potassium, phosphorus and sodium. Finally, data analyzed by SAS software and means compared with LSD test.

The results of analysis of variance showed that not irrigation had a significant effect on grain yield, concentration and yield of studied elements in grain. The highest grain yield (13600 kg ha-1) was obtained in control treatment. In two weeks not irrigation treatment after 49, 63 and 77 days after sowing was decreased by 74.2%, 57.3% and 52.2% to control, respectively. In the three week treatment not irrigation was reduced by 97.4% and 95.2% after 49 and 70 days after sowing. The concentration of the elements in the two and three weeks no irrigation was increased compared to the control. The lowest concentration was observed in the control treatment and the highest in two weeks of irrigation treatment at 77 days after planting (grain filling period) and three weeks no irrigation in 49 days after planting (inflorescence emergence). In not-irrigation treatment for two weeks after 77 days after planting, the concentrations of iron, zinc, copper, nitrogen, potassium, phosphorus and sodium were increased to control 15.5, 11.5, 45.2, 18.8, 12.0 , 38.2 and 33.8% respectively. In the 3-week no irrigation treatment, on 49 days after planting was increased the concentration of these elements to control 10.9, 20.7, 46.1, 25.1, 26.8, 48.2 and 58.3%, respectively. However, the yield elements in the control treatment was the highest and in the two and three weeks irrigation treatment was less than the control, and in the treatment 49 days after planting was the lowest, which was affected by the severe decrease in grain yield at this stage of growth.

In general, the results showed that in each stage of growth and development of maize that faced with drought stress, although the concentration of the elements studied in the grain increased from 10 to 58 percent compared to the control treatment, but due to a significant decrease in grain yield, yield elements were reduced to 96% to control treatments. The most sensitive stage of plant growth to drought stress in this experiment was 49 days after planting or inflorescence emergence stage.