Effects of fertilizers and arbuscular mycorrhizal fungi on the post-vitro growth of micropropagated strawberry

Abstract

— A 5-wk factorial experiment was conducted to examine the effects of osmocote (18N:11P:10K; commer- cial controlled-release fertilizer), rock phosphate and 3 species of arbuscular mycorrhizal fungi on the growth of the strawberry cultivar Senga Sengana in a peat-sand-vermiculite substrate. Three Glomus species, G98 (probably G in- traradices), G128 (an undescribed species) and G geosporum were compared. G98 and G128 significantly increased shoot dry weights compared with the non-mycorrhizal control. Levels of root colonization by G98 and G128 were sig- nificantly greater than by G geosporum. The addition of both fertilizer types significantly increased shoot dry weights. Neither osmocote (0.5-2.0 g/l) nor rock phosphate (1.0-5.0 g/l) addition had a significant effect on colonization by the 3 fungi. An osmocote fertilizer applied at 25% of the minimum recommended commercial rate to mycorrhizal plants was sufficient to produce equivalent dry matter yields as non-mycorrhizal plants receiving the full application of osmo- cote. All 3 fungal species significantly increased the stolon number per plant when compared with the non-mycorrhizal controls. Results clearly show that healthy mycorrhizal strawberry plants can be produced at weaning using commer- cial or reduced rates of osmocote or a rock phosphate formulation. phosphate / fertilizer / arbuscular mycorrhizal fungus / strawberry / micropropagation Rsum — Effet d'engrais et de champignons mycorhiziens arbusculaires sur la croissance post-vitro de frai- siers micropropags. Un essai factoriel de 5 semaines a t fait pour examiner les effets de l'osmocote, (engrais com- mercial diffusion contrle 18:11:10), du phosphate naturel, et de 3 espces de champignons AM sur la croissance du cultivar de fraisier Senga Sengana sur un substrat tourbe : sable : vermiculite. On a compar 3 espces de Glomus G98 (probablement G intradices), G128 (espce non dcrite), et de G geosporum. G98 et G128 ont augment significative- ment les poids sec de tiges, par rapport aux tmoins non inoculs. Les niveaux de colonisation des racines par G98 et G128 taient plus levs que celui de G geosporum. L'addition des 2 engrais a significativement augment le poids sec des tiges. Ils n'ont aucun effet sur la colonisation par les 3 champignons. L'osmocote appliqu 25% de la dose mini- male conseille commercialement suffit pour produire les mmes rendements en matire sche sur les plantes mycorhi- zes que la dose complte sur les tmoins non mycorhizs. Les 3 espces de champignon augmentent significativement le nombre de stolons par plante, par rapport au tmoin. Les rsultats montrent clairement que l'on peut produire des plantes mycorhizes saines de fraisier au sevrage en utilisant des doses commerciales ou rduites d'osmocote ou de phosphate naturel.