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Effect of phosphorus stress on gas exchange, plant growth and mycorrhizal development of Capsicum annuum cv. San Luis (chile ancho pepper)

POSTER X
AGUILERA, L.2, F.T. DAVIES, JR.1, V. OLALDE-PORTUGAL2, S.A. DURAY1 & L. PHAVAPHUTANON1

1Dept. of Horticultural Sciences, Texas A&M University, College Station, TX 77843, and
2CINVESTAV Plant Biology Inst., Irapuato, Mexico

ICOM1 Abstract
Seedlings of Capsicum annuum L. cv. San Luis were grown in pots containing a pasteurized mixture of sand and sandy loam soil inoculated or noninoculated with the endomycorrhizal (VAM) fungus Glomus intraradices. Long Ashton nutrient solution (LANS) was modified to supply phosphorus at 0, 11 or 44 mg P ml-1. Diurnal gas exchange measurements were taken 15, 30 and 50 days after the experiment was initiated. Gas exchange and net photosynthesis were enhanced by mycorrhiza and full strength LANS fertilization (44 mg P ml-1). Under P stress (0 mg P ml-1), VAM plants had greater gas exchange and net photosynthesis compared to Non-VAM plants. At all P levels, the symbiosis increased leaf nutrient content of P, K, Mg, S, Fe, Mn, Zn, Cu, B, Mo, and Al. Mycorrhizal plants had higher shoot dry weights, leaf number, leaf area, and fruit primordia than nonmycorrhizal plants at 0 and 11 mg P ml-1 P. Growth of VAM plants at 0 mg P ml-1 was similar to Non-VAM plants at 11 mg P ml-1 P. Root colonization (arbuscules, vesicles, internal and extraradical hyphae development) were higher at 0 and 11 mg ml-1 P. The quantity of spores recovered in soil was independent of P treatments.