Abstract
BACKGROUND: Due to the increasing human population and the decreasing availability of cultivated land, it has become a challenge to fulfill the demand of food. This challenge can only be obtained by achieving higher yield from limited cultivated land. To accomplish this, farmers are adopting various strategies such as the use of fertilizers, plant growth regulators, nutrient foliar sprays and higher yielding cultivars. Among these approaches, plant growth regulators and micronutrients are equally important for enhancing crop productivity as they are cost- effective, readily available and required in only low concentrations. Indole Acetic Acid (IAA) is a plant growth regulator that is widely used for enhancing crop growth and yield in various crops, whereas Boron (B) plays a crucial role for healthy development of crops. In previous studies,, individual (straight) applications of IAA and B have been extensively studied for various crops including maize but its combined (blended) application has not been reported that is revealing an important research gap. METHODS: To address this gap and the research question about the efficacy of blended IAA + B applications in maize, pot experiments were conducted at the University of Gujrat, Pakistan using two maize varieties i.e. Pak-Afgoi and Golden. There were six treatments of IAA and B (straight and blended) that were applied as foliar sprays after 21 days germination. RESULTS: Foliar applications of IAA and B have shown a significant improved in the growth and productivity of maize plants for straight and blended applications. The most pronounced improvements in morphological traits such as shoot length (65.66 cm), shoot and root fresh and dry weights, number of leaves, leaf area (629.66 cm(2)), relative growth rate (1.8 g/g/day) and net assimilation rate (0.335 g/cm(2)/day) were observed at the concentrations of 20 and 30 ppm IAA and Boron (blended application). Similarly, straight and blended applications of IAA and B had significant effects on physiological and biochemical parameters including chl-a, chl-b, total chl, carotenoids, antioxidant enzyme activities of catalases (CAT) and peroxidases (POD), as well as carbohydrate and protein contents. Highest total carbohydrates (1.326 µg/g), number of seeds (534 seeds per cob) and total grain yield per plant (182.66 g) was calculated at T5 (30ppm IAA + B). From all the treatments, blended applications of 20 and 30 ppm of IAA + B had shown better results for morphological, physiology and yield attributes as compared to straight treatments. Among the two varieties, the Golden variety outperformed Pak-Afgoi in growth and yield under IAA and B treatments. CONCLUSION: In conclusion, the foliar applications of IAA combined with Boron (20 and 30 ppm) proved to be more effective than their individual applications (straight), suggesting that their synergistic effects can be utilized to enhance the morphological, physiological, enzyme activities contributing the productivity of maize.