Evaluation of seed yield and nitrogen accumulation in aerial organs in three corn (Zea mays L.) varieties as affected by different amounts of biological and chemical nitrogen fertilizers

Corn is a crop which grows in a wide range of temperatures and due to its diversity, adaptability and high nutritional value is one of the most important crops in the world. Among the required nutrients by crops, nitrogen is the most important nutrient element affecting the quantitative and qualitative yield of crops. Nowadays, the application of biological fertilizers such as vermicompost has been considered as a suitable alternative for chemical fertilizers. The use of vermicompost gives vitality to the soil due to the activity of microorganisms and it is considered a long-term investment and a permanent part of soil structure.

In order to evaluate the accumulation of nitrate in aerial organs and seed yield in corn as affected by the rate of biological and chemical nitrogen fertilizers, a field experiment was conducted in 2018 cropping season in Guilan Agricultural and Natural Resources Research Center, Iran, Rasht. This experiment was performed as a split plot based on randomized complete block design with three replications. Maize cultivars including 703, 704 and 705 (as main plot) and the rates of different nitrogen fertilizers such as N1 = no use of nitrogen fertilizer (control treatment), N2= 200, N3= 300 and N4= 400 kg nitrogen per hectare and N5= 8500, N6= 17000 and N7= 25500 kg vermicompost per hectare (as subplot) were comprised experimental treatments.

The results of this experiment showed that the highest corn seed yield and dry forage were obtained in 703 and 705 corn varieties as affected by 300 kg nitrogen per hectare, respectively. The greatest nitrogen accumulation was shown in stem of 705 corn variety. The interaction between 705 corn variety and the application of 300 kg nitrogen per hectare, produced the highest stem dry weight. The greatest weight of leaf dry was obtained in 704 crop variety as affected by 25500 kg vermicompost fertilizer per hectare that had no significant difference with the application of 300 kg nitrogen fertilizer per hectare. The application of vermicompost fertilizer increased the dry weight of photosynthetic area of plant (leaf) in 704 variety and decreased 1000-seed weight of corn. Hence, the seed yield of corn decreased in response to vermicompost fertilizer compared to nitrogen fertilizer.

Results showed that the highest rate of nitrogen was accumulated in stem of 705 variety of corn. Increment of the dry weight of leaves in 704 and 705 varieties of corn in response to 300 kg nitrogen per hectare and 25500 kg vermicompost per hectare had no significant difference. The application of vermicompost biological fertilizer in comparison to nitrogen chemical fertilizer could enhance the dry weight of photosynthetic area of plant (leaf) in 704 variety of corn. But, seed yield of corn decreased as affected by biological vermicompost fertilizer compared to chemical nitrogen fertilizer.