Abstract

CALLEJAS-RUIZ, B. A. et al. Substrates and arbuscular mycorrhizal fungi in the production of poinsettia. Rev. Chapingo Ser.Hortic [online]. 2009, vol.15, n.1, pp.57-66. ISSN 2007-4034.

The objectives of the present research were to determine the effect of three substrates on establishment of mycorrhizal symbiosis between Glomus mosseae BEG-25 and G. mosseae BEG-132 and poinsettia plants and on plant development and quality, and to compare plant response to inoculation with commercial fertilization practiced by growers. The substrates consisted of: S1=a mixture of leaf mould+ volcanic rock + peat moss + perlite (9:3:2:2, v/v); S2=peat moss + vermiculite (2:1, v/v) and S3=volcanic rock. Fertilization treatments consisted of non-fertilized plants and plants fertilized with Peters^® 8-45-14 (N-P₂O₅-K₂O) during the initial 20 days, and with Peters^® 7-40-17 thereafter. Plants growing on S1 plus fertilization had the highest plant height (40.8 cm), number of leaves (63.4), shoot dry weight (26.3 g), leaf area (2,518.8 cm²) and bract area of the main inflorescence (1,163.1 cm²), while the highest root dry weight was observed in G. mosseae BEG-132 inoculated plants on S1 and those from S2 plus fertilization. Anticipated flowering, 6 - 3 days, was observed in plants on S1 compared with plants grown on S2 and S3. The highest root colonization was observed not only in plants inoculated with G. mosseae BEG-25 (66%) and G. mosseae BEG-132 (80%), but also in non-inoculated plants (56%), all of them in S1, suggesting that this substrate contained native mycorrhizal fungi. However, none of the mycorrhizal treatments improved plant nutrition. S1 was the best substrate for the establishment of mycorrhizal symbiosis. Fertilization with Peters^® in S1 was the best treatment for plant growth and quality.

Keywords : plant growth; Euphorbia pulcherrima Willd. ex Klotzch; nutrimental concentration; flowering; plant pigmentation; arbuscular mycorrhiza.