Table 3: Herbicide treatment, Analysis of Nitrogen and Carbon, expressed as d.w. % and fern morphology. Azolla treated directly with herbicides becomes generally stressed, with an associated decrease in N and C content until death ensues. Treatments with 6L/ha of Propanil and Oxadiazon were, from the outset, deleterious for Nitrogen and Carbon accumulation. Treatment with 200 g/ha of Cinosulfuron initially caused no change or only a slight increase in Nitrogen and Carbon content. At 13 days, the fresh weight of the samples treated with Cinosulfuron, had shown slight increase of biomass (initial inoculum 20 g on Mar. 29th). However, after this intermediate phase Cinosulfuron caused a progressive deterioration leading to the death of the fern. Only Propanil 6 L ha-1 treatment allowed 60% of plants to survive, albeit with reduced quantities of fixed Nitrogen. Leaflet surface: . We could weigh only floating samples, in Cinosulfuron treatment. The results of ANOVA (data not showed) performed on the nitrogen and carbon content and their ratio, in the herbicide treated samples show significant difference between treatments for the nitrogen and carbon contents, while differences in C/N ratios are less marked. Table shows LSD (Least Significant Difference).

Samples/treatmentApr. 3rdApr. 10thApr. 17th
Dead plant %Leaflet dimensionDead plant %WeightLeaflet dimensionDead plant %N meanStd %C meanStd %C/N mean

W/O treatment on wet soil010103.66.032.45.19.0
OXADIAZON 2 L ha-1 on wet soil03>5031002.14.826.32.712.5
PROPANIL 6 L ha-1 on wet soil<102<202401.816.723.614.013.1
PROPANIL 12 L ha-1 on wet soil>5049041002.58.427.56.911.2
W/O treatment, floating01044 g103.26.235.55.9 11.1
CINOSULFURON 150 g ha-1, floating015027 g11003.45.137.13.810.9
CINOSULFURON 200 g ha-1, floating015021 g1803.81.538.31.210.2

LSD1.416.1