接种pectinolytic菌后根瘤的形成及在油菜根部氮的固定

Nodular structures were formed by rhizobia on oilseed rape oilseed rape roots following treatment with pectinolytic bacteria.Nodules developed within 50 days.Photomicrograph of nodule cells showed that the capsulated bacteria were intracellular.Rhizobia resolated from the root nodules retained not only the ability of nodulation but also the characteristic of resistance to 100μg neomycin mL^-1,A low nitrogenase activity of the nodules was determined by the method of acetylene reduction.     

15N标记的土壤估测某些豆科植物N2固定的温室实验

Pot experiments were carried out to estimate N2 fixation by vetch,milk vetch,sickle alfalfa and broadbean in pure stand using a ^15N-labelled soil.Winter wheat was used as the non-fixing control.The 15N-labelled soil used was prepared by growing corn-wheat-corn successively on a nearly organic-matter-free Xiashu loess supplemented with adequate amounts of (15NH4)2SO4,P,K and micronutrients,then incorporating these 15N-labelled plant materials into the soil after each havest,and allowing the plant materials to be decomposed aerobically for 410d after incorporation of the plant material of the thire crop.The 15N enrichment of wheat plant-N varied slightly with organs,with a maximum difference of 9.8%,Based on 15N enrichment of soil N inferred from the mean value of the 15N enrichment in different organs of wheat 79%-91% of total N in the tops and 67%-74% of total N in the roots of legumes studied were derived from atmosphere .Estimate by isotope dilution method was in good agreement with that by the conventional difference method provided values obtained by the latter were corrected for seed N,and also with that from the measurement of N accumulated in the tops of the legumes.