Abstract

SOTO S., Johana Carolina  and  FILGUEIRA D., Juan José. Effect of photoperiod and light intensity on the sporulation of Peronospora sparsa Berkeley under controlled environmental conditions. Agron. colomb. [online]. 2009, vol.27, n.2, pp.245-251. ISSN 0120-9965.

Downy mildew, caused by Peronospora sparsa, is one of the most restrictive and costly diseases in Colombian rose plantations. The close relation of the disease to climatic conditions determines the need to study the parasite under controlled microclimatic conditions. The objective of the present research was to improve the understanding of the biology of Peronospora sparsa, in terms of the effect of photoperiod and light intensity on the sporulation of the parasite, which was grown on rose leaves under controlled environmental conditions in moist chamber. The evaluated photoperiods were: 24 hours under a light intensity of 1,000 lx; 8, 12 and 24 hours at 790 lx; 8, 16 and 24 hours - 560 lx; 12 hours - 120 lx, and finally complete darkness. Sporulation was favored by 8 to 16 hour photoperiods at 560 lx, and strongly enhanced by 12 hour periods at 790 lx. Permanent light exposure not only showed an inhibitory effect on sporulation, but also determined the production of atypical sporangia (little cytoplasm and small size).

Keywords : downy mildew; rose; peronosporales.

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