A Study On The Rhizosphere Effect Of Wheat In Manganese Deficiency

In this thesis, sensitive and insensitive wheat genotypes to manganese deficiency were selected by solution culture experiment. The organic acids in their root exudates in manganese deficiency were analysed dynamically by high performance liquid chromatography. The acidification and deoxidation ability of these organic acids were compared.At first, the tolerance to Mn deficiency of the 14 wheat genotype were compared by solution culture experiment. The results showed that among different wheat cultivars, their tolerance to Mn deficiency were different. Most of them were sensitive to Mn deficiency, but a few cultivars were insensitive to Mn deficiency. To all of these wheat cultivars, the shoot relative dry weight, the root relative dry weight and the root-shoot ratio were decreased more or less in Mn deficiency, but these items of the cultivars which have high tolerance to Mn deficiency decreased less than that of the cultivars which have low tolerance to Mn deficiency. The tolerance to Mn deficiency of the 14 wheat cultivars were devided into different standing by these items and the phenomera of these wheat cultivars expressed in the field.Second, the methods for separation and determination of nine low-molecular-weight organic acids(oxalic acid, tartaric acid, malic acid, lactic acid, acetic acid, maleic acid, citric acid, fumaric acid and succinic acid) were established by high performance liquid chromatography with ODS2-C18 analysis column, 0.018mol/L KH2PO4 mobile phase adjusted to pH 2.2, flow rate at 0.3-0.4 ml/min, UV detection at 214nm, sample volumn at 20uL.The solution of the organic acids was condensed in 55 C.Third, in Mn deficiency condition, the organic acids in the root exudates of the wheat which had different tolerance to Mn deficiency was researched dynamically by solution culture experiment and high performance liquid chromatography. The results showed that the wheat root can secrete more tartaric acid, malic acid and acetic acid in Mn deficient condition and low Mn condition in a period than in normal Mn condition,but the difference of the organic acids in root exudates between Mn deficient treatment and low Mn treatment was not evident mostly. In Mn deficient treatment and low Mn treatment, the cultivar which has high tolerance to Mn deficiency secreted more tartaric acid and malic acid in a longer time than that of the cultivar which has low tolerance to Mn deficiency and the former could still secrete acetic acid in a relative high level after the maximum exudation, but this ability of the latter was very low. The total quantity of the organic acids in the root exudates of the cultivar that has high tolerance to Mn deficiency increased more than that of the cultivar that has low tolerance to Mn deficiency in no Mn and low Mn treatment. The content of maleic acid and fumaric acid in the root exudates were very low, and Mn deficiency treatment and low Mn treatment didn't increase the content of these two organic acids in the wheat root exudates.At last, the acidification and deoxidation ability of these organic acids were compared. The results showed that the acidification ability were different among different organic acids and they had different ability to deoxidize KMnO4. The acidification ability and the ability to deoxidize KMnO4 were increased with the concentration of the organic acids.