Abstract Amelioration of iron toxicity (i.e. Bronzing) by pulsed [Ca2+] through root dip treatment (RDT) of transplanted Bahadur (iron susceptible) and Mahsuri (iron resistant) rice varieties were studied in field condition (initial soil pH 4.68, mean [Fe2+] =954.98.ppm). An increase in [Ca2+] in leaf was detected commensuration with [CaCl2] » 100-1000ppm in RDT for 24h, which was higher in Bahadur > Mahsuri. A decline in soil pH (increased acidity) was observed along with the days after transplanting. So, available [Fe2+] in soil decreased from 67% to 80% at 30-90 DAT. The [Fe2+] in soil caused reduction in chlorophyll (»54%). Increase in [CaCl2] >100ppm in RDT lessened chlorophyll (»21.77%) and leaf area (»18.11%) at 90DAT of the crop. Over all, Bahadur was superior than Mahsuri in most of the physiological parameters viz., panicle no.m-2 (by 28.20%), no. of spikelet per panicle (by 23.76%), 1000 grain weight (by 24.78%), sink capacity (by 59.77%) and economic yield (by 43.09%). 100ppm CaCl2 RDT brought positive relationship between yield and its attributes viz., spikelet, r =0.264, 0.657, test weight, r=0.315, 0.402, sink capacity, r=0.196, 0.491) in Bahadur and Mahsuri respectively at 30 days after transplanting under higher iron condition in field.
The paradigm of Bronzing in rice caused by higher [Fe2+] in leaf derived from acid soil, and prophylactic role of Ca2+ ameliorating the disorder in field condition is discussed in this paper.
Keywords : Acid Soil; Bronzing; Calcium; Chlorophyll; Correlation Coefficient (R); Iron; Leaf Area; Root-Dip; Sink Capacity; Test Weight.