Introduction: Corn (Zea mays L.) is one of the oldest agricultural plants, which has a special place among agricultural products due to its favorable characteristics, such as high adaptation to climatic conditions, high production of dry matter, and high-water use efficiency. The high production potential of corn and its importance in feeding livestock and poultry, as well as the variety of products obtained from corn, have caused this plant to attract the attention of many countries in the world. Management practices can affect the growth and yield of maize. One practice used to increase yield has been to adjust the proper planting orientation and spacing between maize rows. Increasing the productivity per unit area through crop management is one of the most important factors affecting yield optimization. Basically, corn breeders are interested in obtaining genotypes that are desirable in terms of functional traits and other agricultural traits. Optimal leaf removal and appropriate row spacing through improving light distribution and photosynthetic capacity are associated with increases in grain yield. The amount of corn yield per hectare varies in different areas and depends on the environmental conditions, crop variety, the amount of fertilizer consumption, irrigation, and the fight against pests and diseases, and many other conditions. According to the climatic conditions of each region and the characteristics of cultivars, one of the important factors for more production per unit area is choosing the appropriate density.
Materials and Methods: In this study, field experiments based on split-split plot arrangement based on a complete randomized block were conducted to analyze the effects of leaf removal (control, no leaves removed; 100% leaves in 7-leaf stage; 50% leaves in 14-leaf stage; 100% leaves in 14-leaf stage; 50% leaves in blister stage; and 100% leaves in blister stage) and different row spacing (40 and 70 cm) on morphological traits of two maize cultivars (KSC 701 and KSC 201) in Bam city (Kerman, Iran).
Results & Discussion: Increasing the productivity per unit area through agricultural management is one of the most important factors affecting yield optimization. Defoliation and appropriate planting row spacing are associated with increased grain yield through improved light distribution and photosynthetic capacity. Plant height, stem diameter, plant dry weight, and leaf dry weight decreased with increasing levels of defoliation and planting row spacing during reproductive stages. The traits related to corn seed yield were significantly influenced by the spacing of planting rows and defoliation levels and their interaction. The highest seed yield was obtained in the first and second years, 13505.51 and 17952.60 kg per hectare, respectively, in the treatment of removing 50% of leaves at the blister stage. Removal of 50% of leaves at the blister stage and 70 cm planting row spacing are recommended as suitable treatments for cultivation in the region.
The results of two consecutive years showed that the effect of planting pattern was significant on corn grain yield at the 5% statistical level, and the effect of cultivar was significant on corn grain yield at the 1% statistical level.
Maize is one of the main crops in the southern region of Iran. Reasonable plant-row spacing, leaf removal, and planting patterns are the key factors for high-yield and efficient crop cultivation. Our results indicated that different cultivars had different responses to plant density by adjusting yield components. Leaf removal can increase both total dry-matter accumulation and thus also grain yield. The mentioned results in agreement with previous international research. Also, optimal leaf removal and row spacing improved light distribution, increased photosynthetic capacity, and thus the grain yield.
Conclusion: Overall, the 50% leaf removal in the blister stage, 70 cm row spacing, and Karun and Koosha variety are recommended as the suitable treatment and variety for cultivation in the area.