Plant growth regulators affecting maize leaf senescence and area index impact yield under drought

Abstract

Increasing leaf area duration (LAD, delaying leaf senescence) may be a suitable method to enhance maize (Zea mays L.) growth in drought stress conditions. Accordingly, it was hypothesized it is possible to enhance maize tolerance to drought stress conditions using plant growth regulators (PGR), which may increase leaf area index and delay leaf senescence. The experiments, conducted in two different sites in the province of Fars, Iran in 2018, were split plot on the basis of a complete randomized block design with four replications. Water stress (main factor) including control (S1) mild (S2), and sever stresses corresponding to irrigation after 80, 100- and 120-mm evaporation, respectively, and PGR (sub factor) including water spray (control), benzyl-adenine (45 mgL−1), proline (45% concentration), salicylic acid (45 mgL−1) superoxide dismutase (2.5 mgL−1), and their combination were tested. Drought stress significantly affected the measured parameters including leaf area index and durability, SPAD index, plant height, total dry weight, grain filling rate, peduncle length, number of grains per cob, biological and grain yields, and harvest index. However, the tested PGR, especially the combined one, were able to alleviate the stress by enhancing leaf indexes, and maize grain yield and its components in stress conditions. The tested PGR numerically increased LAD (delayed senescence) at S3 compared with S2. It is possible to alleviate the unfavorable effects of drought stress on maize growth and yield production, using the tested PGR, which may enhance leaf related parameters including LAI and LAD (delaying leaf senescence).