The Effects of Aluminum on Fiber and Protein Bound Condensed Tannin, Polyphenols and Some Growth Index in Two Sorghum Cultivars

摘要

The effect of Al on fiber and protein bound condensed tannin, polyphenols, tannin and some growth index in two cultivars of Sorgkum (cult 132 and 552) has been investigated. The medium culture was river sand and peat in 3:1 ratio, respectively. All pots received Hoagland's nutrient solution with and without A1C13. The first plant samples were obtained 30 day after sowing and the others were obtained each two weeks interval (days, 30, 44, 58, 72, 86, 90, 114 and 128) up to the end of plant's vegetative growth. Plant4ry weight, growth rate and leaf area were measured and then total tannin, fiber and protein bound condensed tannin, total polyphenols in eight successive harvests were compared. The results indicated that the mean growth rate for cultivars 132 and 552 in control plants were 255 and 196 mg/plant/day, respectively and when Al contributed in the growth medium, the mean growth rates were reduced to 224 and 170 mg/plant/day in cultivars 132 and 552, respectively (almost 36% reduction). In average, leaf expansions were 6.4 and 4.5 cm~2 day~(-1) in cultivar 132 and 552, respectively and Al significantly decreased (p<0.001) the leaf area by 11.3 and 7.1 % in cultivar 552 and 132, respectively (p<0.001). Al causes to increase the concentration of Protein Bound Condensed Tannin (PBCT) in leaves of two cultivars with different patterns. In cultivar 132, PBCT was accumulated almost in a rate of 0.075 mg g~(-1) DW day~(-1) in plant during growing season. In contrast, in cultivar 552 the amount of PBCT was the same at early stage of growth in plants treated with Al and then increased slightly afterward. Although the root's PBCT were lower in cultivar 552, their amounts were decreased up to the end of growing season. This behavior was completely different in cultivar 132. Adding Al into nutrient media would change the pattern of PBCT in root The amounts of PBCT in control plants were higher than fiber bound condensed tannin. However the trend was different in different cultivars respect to Al toxicity. Amount of total polyphenols in control plants were higher in cultivar 132 (90.9 mg g~(-1) DW) than cultivar 552 (52.6 mg g~(-1) DW) during growing season however Al has no significant effect on the amount of total polyphenols except at late stage ofgrowth in which Al increased total polyphenols in both cultivars. Total tannin in cultivar 132 was peaked at middle stage of growth and was lower at younger and elder leaves. Al causes to increase the total tannin at elder leaves.