Production et croissance des plants d’Acacia sur des substrats à base de tamisat de compost dans une pépinière hors sol (Tunisie)

Abstract

This study proposes an attempt to optimize the forestry compost produced at

the nursery forest aboveground Chott Mariem -Sousse in Tunisia, by varying

the particles size using different techniques and different riddling methods, to

develop a substrate based on forestry sieved product suitable for breeding in

containers of hardwood plants of Acacia cyanophylla. Tamisats which have

acceptable porosity and the current substrate not sieved (100 % crude

forestry compost derived from Acacia homogenate) underwent an indirect

morphological characterization based on assessments of germination and

growth (height, diameter and robustness ratio) of produced plants. Regarding

seed germination, the test results conducted in the laboratory have shown

the good quality of seeds used. Similarly, the % germination is almost the

same on all substrates tested, that’s why the riddling didn’t reveal significant effect. According to the results of the average evolution of the height and

diameter of seedlings, it appears difficult to distinguish the effect of substrate

on their behavior during the first month after seedbed. The other two

followed observations of growth, made five and seven weeks after planting

showed similar growth on crude compost and tamisats from the simple sifting

respectively 6, 8 and 12 mm, however, we can note a small difference in favor

of coarse tamisats from double riddling of refusal, respectively of the mesh 6

mm on the mesh 8 mm and of the mesh 8 mm to the mesh 12 mm. The

measured values of robustness ratio are in favor of the tamisat stem from the

double riddling of refusal of the mesh 6 mm on the mesh 8 mm, however, this

judgment remains to be confirmed as the vegetative development stage

considered was not advanced.