The Nutrition Mechanism Of Grain Amaranth Enrichment In Potassium

1. The experiments of water culture and soil culture were conducted to screen the genotype ofgrain amaranth in Capability of enrichment in potassium, the content .uptake rate and uptake ratio of potassium in per-plant was used to the screening index of genotype of enrichment in potassium .The grain amaranths were cultured in low potassium solution about 30 days and in deficiency potassium soil about 60 days, the results showed that the species/cultivars of D8-1, R109x R104 and K12 had high capability of enrichment in potassium, the contents of potassium in plant were usually between 3% and 4%,the uptake rates of potassium in per plant were 50~75mg and 100~120mg , respectively ,the uptake ratios of potassium were over 1.70 umol·g-1 RFW · hr-1, the species/cultivars of D8-1, R109, R104 and K12 were called enrichment genotype. However, the species/cultivars of M9 and Cr047 had low capability of enrichment in potassium, the contents of potassium in plant usually were below 2.7% ,the uptake rates of potassium in per plant were below 40mg and 80mg, respectively ,the uptake ratios of potassium were below 1.30 μmol·g-1RFW ·hr'1, the species/cultivars of M9 and Cr047 were called common genotype. The differences of capability enrichment in potassium were very significant between different species of grain amaranths grown on deficient potassium soil after 60 days of seeding and in water culture after transplanting 30 days. The contents and uptake rates of potassium,which were between 2 and 5 times,4 and 10 times .respectively than in low potassium solution,were greatly increased in all species/cultivars,when the level of potassium was 5mmol· L-1 in water culture. However, the capability of enrichment in potassium was reduced with the increasing of potassium content in solution.Under the low potassium level water culture,the maximal contents and uptake rates of potassium were 2.5 and 2.3 times than the minimum in all species, respectively, but it were only were 1.3 and 1.8 times than the minimum in all species in normal potassium water culture, respectively. While, the ration of roots and shoots and the length of main root on deficient soil were two genotypes were only half or so than that were in low potassium water culture. No matter what kinds of medium culture was used, root/shoot and the length of mainroot in genotype enrichment in potassium were more than that of common genotype2. Under deficient potassium soil culture and different potassium water culture condition,the changes of contents of different potassium forms were studied .which were in the soil of rhizosphere and non-rhizosphere in different grain amaranth genotypes.While the changes were investivagated,which were in the quantities of microorganisms in rhizosphere, ,rates of important root exudates and H+ secretion and CEC of roots. The results were indicated that the content of available and slowly available potassium in rhizosphere was higher than that in non-rhizosphere , which formed a area enrichment in potassium comparatively in the rhizosphere.The ability of accumulated potassium in the enrichment genotype was significantly higher than in the common genotype. The content of total potassium of soil in rhizosphere was lower than in the non-rhizosphere , the decreasing extent of total potassium in enrichment genotype was higher than in the common genotype.Compared with the common genotype, the quantities of microorganism in rhizosphere and the exudation rates of main root exudates in enrichment genotype were higher significantly,while the changes of the quantities of bacterium and fungi in rhizosphere was same as the root exudates.CEC of root and the rates of H+ secretion in enrichment genotype were higher than in common genotype,but they were not significant difference in varieties of the same genotype.3. Under water culture condition,the differences and the kinetics parameter of potassium uptake were investigated in physiological and morphological characteristics of roots by enrichment and common gra...