Abstract
The present study analyses growth and chlorophyll biosynthesis in young maize seedlings in response to Zn supply over a wide range of concentrations. Supply of 0 - 5 mM ZnCl2 to 3 days old light grown maize seedlings led to gradually increased accumulation of Zn in the shoot tissue, while in the root tissue substantial increase was observed at/and above 0.1 mM ZnCl2. Zn supply significantly reduced the overall growth of maize seedlings mostly at 1 - 5 mM ZnCl2 exerting strong correlation and the observed effect was more substantial for root tissue. Amongst the biochemical parameters, increase in protein and proline content was more prominent in root tissue than the shoot, while RNA content was reduced in shoot tissue. Zn treatment to light grown seedlings significantly increased the chlorophyll, carotenoid content, while in dark grown seedlings it had marginal/no effect. Delta amino levulinic acid (ALA) content in both the regimes was increased at higher Zn concentrations. Also ALA synthesis was increased in both the regimes, but non significantly. Zn enhanced ALA dehydratase (ALAD) activity of light as well as dark grown seedlings being significant in former. The results demonstrate that the Zn accumulation and growth effect at higher Zn concentrations in maize depend upon the tissue with root as the target site and shoot growth are mainly influenced by ALA and subsequently ALAD in maize seedlings.
Highlights
IntroductionIts deficiency as well as toxic symptoms has been found in different plants
Zn supply significantly reduced the overall growth of maize seedlings mostly at 1 - 5 mM ZnCl2 exerting strong correlation and the observed effect was more substantial for root tissue
The results demonstrate that the Zn accumulation and growth effect at higher Zn concentrations in maize depend upon the tissue with root as the target site and shoot growth are mainly influenced by amino levulinic acid (ALA) and subsequently ALA dehydratase (ALAD) in maize seedlings
Summary
Its deficiency as well as toxic symptoms has been found in different plants. Zn deficiency reduces various physiological processes, such as, net photosynthesis [1], tissue water content and P and Mg concentrations [2] in plants. Toxic effects of Zn in plants influencing different functions have been reported, such as, high concentrations of Zn decrease net photosynthesis and respiration rate in Beta vulgaris [3], generate reactive oxygen species, and decrease the chlorophyll content and shoot yield [4]. Zn effects on plant growth varies in different species, decrease has been observed in ryegrass [5], clusterbean [6], in sugarbeet [7], and in Sorghum [8] while in Eruca sativa seedlings increase is reported [9]
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