Abstract
Aluminum (Al) is the third most abundant metal in earth crust, whose chemical form is mainly dependent on soil pH. The most toxic form of Al with respect to plants is Al3+, which exists in soil pH <5. Acidic soil significantly limits crop production mainly due to Al3+ toxicity worldwide, impacting approximately 50% of the world’s arable land (in North-Eastern India 80% soil are acidic). Al3+ toxicity in plants ensues root growth inhibition leading to less nutrient and water uptake impacting crop productivity as a whole. Rice is one of the chief grains which constitutes the staple food of two-third of the world population including India and is not untouched by Al3+ toxicity. Al contamination is a critical constraint to plant production in agricultural soils of North East India. 24 indigenous Indica rice varieties (including Badshahbhog as tolerant check and Mashuri as sensitive check) were screened for Al stress tolerance in hydroponic plant growth system. Results show marked difference in growth parameters (relative growth rate, Root tolerance index, fresh and dry weight of root) of rice seedlings due to Al (100 μM) toxicity. Al3+ uptake and lipid peroxidation level also increased concomitantly under Al treatment. Histochemical assay were also performed to elucidate uptake of aluminum, loss of membrane integrity and lipid peroxidation, which were found to be more in sensitive genotypes at higher Al concentration. This study revealed that aluminum toxicity is a serious harmful problem for rice crop productivity in acid soil. Based on various parameters studied it’s concluded that Disang is a comparatively tolerant variety whereas Joymati a sensitive variety. Western blot hybridization further strengthened the claim, as it demonstrated more accumulation of Glutathione reductase (GR) protein in Disang rice variety than Joymati under stressed condition. This study also observed that the emergence of lethal toxic symptoms occurs only after 48h irrespective of the dose used in the study.
Highlights
Aluminum (Al), the third most abundant mineral in earth crust, solubilizes into its most phytotoxic species Al3+ in acidic soil from non-toxic Al silicates and oxides [1]
Al, especially in case of rice when the field is flooded due to acidic soil Fe2+ increases in the water leading to iron toxicity [2]). 40–50% of the world’s arable soils is acidic which when summed with abundance of Al present in the earth crust leads to Al3+ phytotoxicity [3, 4]
The root length was less reduced in Disang, Swarna sub 1 C, Naveen, Lachit, while reduction was more profound in Joymati, Tulsi Joha, CR Dhan 601, and KMJ-10-1-4 respectively, due to Al treatment for 48h and 100 μM Al concentration compared to other genotypes (Table 1)
Summary
Aluminum (Al), the third most abundant mineral in earth crust, solubilizes into its most phytotoxic species Al3+ in acidic soil from non-toxic Al silicates and oxides [1]. Initial and most dramatic symptom of Al toxicity is rapid inhibition of root elongation, and root relative elongation rate has served as a typical marker for level of Al toxicity and tolerance capacity in plants [7]. This effect is caused due to damage in the cells at the root apex which in turn leads to a reduced and stunted root system subsequently impacting the grain quality and plant yield [8, 9]. The symptoms in the roots system like, inhibition of root growth, reduced water and mineral uptake caused by Al3+ phytotoxicity starts to appear within minutes after exposure [10]
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
