Document Type : Original Article
Authors
1 PhD, Agronomy, Mailing Address: Department of Agronomy and Plant Breeding, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
2 Professor, Agronomy, Crop Physiology, Mailing Address: Department of Agronomy and Plant Breeding, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
3 Associate Professor, Agronomy, Crop Physiology, Mailing Address: Department of Agronomy and Plant Breeding, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
4 Professor, Agronomy, Crop Physiology, Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, USA
Abstract
Introduction
Drought is known as the most important factor limiting corn production in the world. Depending on the growth stage and severity of drought stress, it can decrease corn yield by 76%. In addition, the increase in drought stress can decrease the efficiency of elements such as nitrogen in this crop. Therefore, many ways have been studied to decrease the effects of drought stress on crops. The results show that the use of cover crops can be an important approach for agriculture to protect crops against climate changes. These crops improve crop yields and soil nutrients by reducing runoff and soil erosion. The use of legumes as cover crops can decrease the need for chemical nitrogen fertilizer by biological N fixation in these crops.
Materials and methods
In 2019, a pot experiment was conducted in the greenhouse of the Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran. The experimental treatments were faba bean cultivation (cultivated, non-cultivated), the different rates of nitrogen based on urea (0, 50, 100% of the recommended amount) and water deficit stress (40, 60, 80, 100% FC). In this experiment, 72 pots of 10 kg were used. First, the field capacity of the soil was determined, then the pots were filled with the air-dried soil. Ten grains of faba bean were planted in each pot, 5 of which were removed after germination. Shoots of faba bean were cut at the 50% flowering stage and mixed with the soil to the depth of 10 cm. Four corn grains were planted in each pot, two of which were removed after germination. In this experiment, the variety Shadan of faba bean and the corn hybrid 201 (single cross) were used. Different levels of nitrogen were applied at the V5 stage of corn, drought stress was applied ten days later and continued until the harvest stage of corn. Pots were weighed regularly for the application of drought stress. Corn was harvested at the pasty stage. Experimental characteristics included grain and shoot fresh and dry weights, grain and shoot protein content, nitrogen agronomic efficiency, nitrogen productivity, nitrogen recovery efficiency, and shoot and grain partial factor productivity. Statistical analysis of data was performed using SPSS software (version 26), and significant differences between treatment means were tested using Duncan's Multiple Range Test at P < 0.05.
Results and discussion
Our results showed that all traits were influenced by interactions between faba bean cultivation × N fertilizer × water deficit stress. The highest grain yield was obtained of treatment the faba bean cultivation+100% of the recommended nitrogen rate+no application of water deficit stress, while no grains were observed in the treatment of non-cultivation of faba bean+100% of the recommended rate of nitrogen+application of severe water deficit stress, non-cultivation of faba bean+no nitrogen application+application of moderate water deficit stress and non-cultivation of faba bean+no nitrogen application+application of severe water deficit stress. The higher rate of nitrogen in the soil under severe water deficit stress can be considered as the limiting factor for crop growth, and therefore we observed lower yields in these treatments. Addition, our results showed that faba bean cultivation as cover crop increased some traits such as fresh and dry weight of shoot, agronomic efficiency and nitrogen recovery of nitrogen compared to non-cultivation of faba bean. The highest fresh dry shoot weight was obtained from the treatments of faba bean cultivation+100% of the recommended nitrogen rate+no application of water deficit stress and non-cultivation of faba bean cultivation+100% of the recommended nitrogen rate+no application of water deficit stress. Also, the highest shoot and grain agronomic efficiency was observed from the faba bean cultivation+100% of the recommended nitrogen rate+ no nitrogen application+application of moderate water deficit stress.
Conclusion
Overall, our results showed that the use of faba bean as cover crop can decrease the effects of water deficit stress and improve the growth status of corn, although the increase at higher water deficit stress level is lower than the other levels. Based on the results, it can be concluded that the use of faba bean as cover crop and and 50% of the recommended rate of nitrogen can be recommended under the same conditions (under water deficit stress).
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