Plant Growth Regulator-Brassinolide for Mitigating Field Waterlogging Stress on Maize

Abstract

Aim: To assess the pleiotropic role of a plant growth regulator, commercially identified as brassinolide (BR) in mitigating waterlogging stress imposed on maize.
 Study Design: A factorial combination of two maize varieties [Ikom White (IKW) and Oba-98], two BR levels (0 and 250 ml) and two waterlogging stages of maize growth [control (WL0) and seedling stage (WL1)], arranged as a split-split plot in a randomized complete block design with three replications was used.
 Place and Duration of Study: Akpabuyo Local Government Area, Cross River State-Nigeria. A two-year field experiment was conducted during the dry seasons of December 2016 and December 2017.
 Methodology: Waterlogging test was conducted on plots by demarcating them with 3.6 by 1.7 m metal sheets buried to a depth of 60 cm to prevent lateral soil-water movement. Two maize seeds were sown at 25 cm within and 75 cm between rows. The BR (250 ml) was sprayed foliar at 21 DAS. The non-waterlogging plots served as control. Observations were made on growth and yield variables as well as the plant's physiological traits.
 Results: Waterlogging significantly reduced the growth attributes of maize and increased (p≤0.05) the leaf moisture content. The photosynthetically active radiation on maize plants was substantially reduced (p≤0.05) by the waterlogging stress. Dry matter yield (DMY) and nutrient uptake in the leaves, stems and grains were reduced (p≤0.05) at both silking and at harvest. The effect of the BR was greater in Oba-98 with higher nutrient contents, radiation absorption, dry matter and grain yields than IKW.
 Conclusion: Treatment of maize plants with BR could induce some tolerance of field waterlogging. Thus, for optimum efficiency in maize production under stressed soil condition of waterlogging, it is recommended that the foliar spray of BR at the 250 ml per plant rate be considered.