Effect of Prolonged Drought on Chlorophyll Fluorescence, Yield and Water Use Efficiency of Summer Maize

Abstract

【Objective】 Drought is a common stress faced by crops during their growth. Its impact on crop growth and ultimate yield depends on when droughts occur as well as their duration and severity. This paper is to investigate the impact of prolonged droughts on chlorophyll fluorescence, yield and water use efficiency (WUE) of summer maize, and provide a guidance for enhancing drought resistance and ensuring stable yield of summer maize. 【Method】 Pot experiment was conducted at a site with mobile rain shed covering. Maize variety DHA757 was used as the model plant; the drought was artificially imposed at jointing-stage (B), tasseling stage (C), and filling stage (G), respectively, at normal (CK), light (1), medium (2), or heavy (3) level. There were nine treatments: two drought treatments with different severity occurring only at jointing-stage, three consecutive droughts occurring continuously across jointing and tasseling stages, three consecutive droughts occurring continuously across jointing, tasseling and filling stage, and one control (without drought). In each treatment, we measured water consumption, Fv/Fm, Fv/Fo, yield, and water use efficiency (WUE) of the crop. 【Result】 Continuous drought significantly reduced water consumption, SPAD, Fv/Fm, and Fv/Fo of the maize, compared to the control. The decrease in these parameters increased with drought severity. All drought treatments reduced the crop yield. For the single drought treatment at the jointing-stage, the yield reduction of B3 was most significant, followed by B2. For droughts lasting two stages and three stages, light droughts did not result in a significant reduction in yield, but other droughts reduced the yield significantly. Compared to CK, B2, B1+C1 and B2+C2 increased WUE by 5.1%, 2.8% and 6.3%, respectively, indicating that a light drought was beneficial to improving WUE. 【Conclusion】 Considering both yield and WUE, a medium drought at the jointing stage (with soil water content dropping to 50%~60% of the field capacity), and a prolonged drought lasting two stages with the soil water content in the range of 60%~70% of the field capacity are suitable for reducing water evaporation without considerably compromising the yield. Our results provide guidance to help sustain summer maize production in regions susceptible to drought.

Keywords

• continuous drought
• summer maize
• chlorophyll fluorescence characteristics
• yield
• water use efficiency