Straight and Blended Applications of Iaa (Indole Acetic Acid) and Boron (B) for the Improvement of Crop Productivity in Maize (Zea Mays L.)

Indole Acetic Acid (IAA), a plant growth regulator, is well-known for enhancing crop growth and yield. Similarly, micronutrients like Boron (B) play a crucial role in the healthy development of crops. While the individual (straight) applications of IAA and B have been extensively studied in maize, their combined (blended) application has not been reported for this crop, revealing a significant research gap. To address this, a series of experiments were conducted at the University of Gujrat, Pakistan, using two maize varieties: Pak-Afgoi and Golden. Six different levels of IAA and B were applied as foliar sprays (straight and blended), 21 days after germination. The results demonstrated that foliar applications of IAA and B significantly improved the growth and productivity of maize plants. The most pronounced improvements in morphological traits—such as plant height, shoot and root fresh and dry weights, number of leaves, leaf area, relative growth rate (RGR), and net assimilation rate (NAR) were observed at a concentration of 30 ppm IAA and Boron (blended). Furthermore, applications of IAA and B enhanced the physiological and biochemical parameters, including chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, antioxidant enzyme activities i.e. catalases (CAT) and peroxidases (POD), as well as carbohydrate and protein contents. Yield related traits, such as the number of cobs and seeds per plant and overall grain yield were also positively influenced by IAA and B. Among the two varieties, the Golden variety outperformed Pak-Afgoi in growth and yield. In conclusion, the foliar applications of IAA combination with Boron (blended) proved to be more effective than their individual applications (straight), suggesting that their synergistic effect can be utilized to enhance the morphological, physiological, and yield attributes of maize.