Amelioration in Growth and Physiological Efficiency of Sunflower (Helianthus annuus L.) under Drought by Potassium Application

ABSTRACT

The present study investigated the induced drought tolerance in sunflower through foliar application of potassium (K) at critical growth stages (head formation or achene filling). Five genotypes of sunflower (G-101, SF-187, Hysun-33, Hysun-38, and 64-A-93) were tested for drought tolerance at −0.55, −1.36, and −1.60 MPa osmotic potential using polyethylene glycol 6000. Hysun-33 showed the highest stress tolerance index as calculated from germination percentage, seedling height, root length, and dry matter. This genotype was further evaluated in the field under drought at head formation or achene filling stages, with or without 1% K foliar application. Treatments were arranged in a randomized complete block design with three replicates. Drought at head formation or achene filling stage significantly decreased biological yield, head diameter, plant height, 1000 achene weight, and achene yield as compared to unstressed control. Potassium application significantly improved all the aforementioned parameters and therefore could be a better strategy for ameliorating drought stress in sunflower.

KEYWORDS:

• Drought tolerance
• foliar application
• potassium
• sunflower genotypes

Acknowledgments

We are equally indebted to the Islamia University of Bahawalpur, Pakistan, for providing experimental and technical support for the study. Special thanks are due to Prof. (Rtd) Dr. Muhammad Aslam for English proofreading of the manuscript.

Additional information

Funding

The financial support for this study provided by the Higher Education Commission of Pakistan to the first author (PM-IPFP/HRD/HEC/2012/2776) is gratefully acknowledged.