SANITARY IMPROVEMENT OF FOUR ORNAMENTAL SHRUBS : CONSEQUENCES FOR THE YIELD AND THE MINERAL CONTENT OF THE BIOMASS
An experiment has been implanted in a nursery soil with high mineral fertility. The choosen species : Ligustrum ovalifolium aureovariegatum, Spiraea bumalda "Anthony Waterer", Tamarix pentandra, Viburnum opulus roseum have been planted in spring 1983. Two origins of each species were used : control and regenerated. The yearly biomass produced by plants grown as mother plants was yielded and weighed after oven drying. The major and minor elements contents have been determined on the dry matter.
The results are the following :
- biomass : the production increases with the time and depends on the species. The effect of the sanitary improvement is nul in the case of Ligustrum, Spiraea, Tamarix but positive for Viburnum.
- mineral content : the four species do not differ by their P, Mg, Zn contents but are significantly different in N, K, Ca, Fe, Mn contents. A species ranking is given for each kind of mineral element. The effect of the sanitary improvement is nul for all determined mineral contents in the case of Ligustrum, Spiraea and Tamarix. In the case of Viburnum, the N, P, K, Ca, Mn contents are lower with the regenerated plant. As the effect is highly significant for Vurburnum K and Ca contents, it is discussed about the relations between plant susceptibility to fungal, bacterial, viral diseases and K-Ca nutrition.