Abstract
Two maize inbred lines, the foundation genotype Y478 and its derived line Z58, are widely used to breed novel maize cultivars in China, but little is known about which traits confer Z58 with superior drought tolerance and yield. In the present study, responses in growth traits, photosynthetic parameters, chlorophyll fluorescence and leaf micromorphological characteristics were evaluated in Y478 and Z58 subjected to water-deficit stress induced by PEG 6000. The derived line Z58 showed greater drought tolerance than Y478, which was associated with higher leaf relative water content (RWC), root efficiency, and strong growth recovery. Z58 showed a higher stomatal density and stomatal area under the non-stressed condition; in these traits, both genotypes showed a similar decreasing trend with increased severity of water-deficit stress. In addition, the stomatal size of Y478 declined significantly. These micromorphological differences between the two lines were consistent with changes in physiological parameters, which may contribute to the enhanced capability for growth recovery in Z58. A non-linear response of Fv/Fm to leaf RWC was observed, and Fv/Fm decreased rapidly with a further gradual decline of leaf RWC. The relationship between other chlorophyll fluorescence parameters (photochemical quenching and electron transport rate) and RWC is also discussed.
Highlights
Plants usually experience fluctuating water supply during their life cycle because of variation in rainfall
Leaf Relative Water Content Under well-watered conditions, the leaf relative water content (RWC) showed no significant difference between the two maize genotypes (Figure 1(a))
Under progressive water-deficit stress conditions, the leaf RWC was significantly higher in the derived line Z58 than in the foundation genotype Y478
Summary
Plants usually experience fluctuating water supply during their life cycle because of variation in rainfall. Plant responses to water-deficit stress [1,2] and growth recovery [3,4] are complex and differ with intensity of water shortage and crop genotype. It is essential to understand the physiological and/or morphological processes that occur in the guard cells during progressive water-deficit stress and stress recovery [3]. Plant responses to water-deficit stress have been studied extensively, including biochemical and physiological processes as well as some molecular events [4,5,6]. Many researchers reported that an increase in stomatal density and a decrease in stomatal length may enhance the adaptability of a plant to drought [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
