Abstract
Water is a limited resource and is likely to become even more restricted with climate change. The aim of this study was to evaluate the effect of humic acid (HA) applications on photosynthesis efficiency of rapeseed plants under different watering conditions. Water stress strongly increased electron transport flux, probability that trapped excitation can move an electron into the electron transport chain beyond QA, and quantum yield of reduction of end electron acceptors at the PSI acceptor side. Application of HA decreased the values of these parameters to be similar to those of non-stress conditions. We found that, the application of HA improved plants net photosynthesis under water stress via increasing the rate of gas exchange and electron transport flux in plants.
Highlights
Productivity of plants depends on environmental conditions
There is no detailed study on the effect of humic acid on the photosynthetic activity of plants under water stress, our research aimed to investigate this by the JIP-test in rapeseed
chlorophyll fluorescence (ChlF) transients of dark-adapted rapeseed leaves were plotted on a logarithmic time scale from 0.01 up to 1,000 ms (Fig. 1)
Summary
Productivity of plants depends on environmental conditions. Water stress is considered one of the most important environmental stresses limiting plant growth and crop productivity. Plants develop various strategies to eliminate the negative impacts of drought (Allakhverdiev and Murata 2004, Jithesh et al 2006, Kalaji and Łoboda 2009), such as escape, dehydration avoidance, and development of physiological tolerance to drought (Berger et al 2010). Water removal induces cell shrinkage, increasing the cytoplasm viscosity and cell wall folding, which results in membrane destruction and protein denaturation (Flexas et al 2000). Drought resistance is typically based on an increased activity of antioxidant enzymes (Lu et al 2007) and changes in plant morphology, anatomy, physiology, and biophysics (Jajoo and Kawamori 2006, Kreslavski et al 2009).
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