Effects of different organic anti-fungal treatments on tomato plant productivity and selected nutritional components of tomato fruit

Organic farming and horticulture require the use of more environmentally-friendly chemicals to reduce potentially harmful side-effects on producers and on consumer health. Sulphur is one of the most important natural fungicides used in organic farming to protect plants against attack by powdery mildew (Leveillula taurica). The use of natural elicitors to induce natural resistance against fungal diseases may provide an alternative to conventional treatments. In this work, we compared the effects of wettable sulphur and two elicitors (Chitoplant (R) and Milsana (R)) on the productivity and nutritional quality of tomato (Solanum lycopersicum L cv. Belladonna). Both elicitors, and a conventional sulphur treatment resulted in a similar degree of protection against powdery mildew. One or more of these three treatments positively affected the concentrations of some natural phytochemicals in tomato fruit (e.g., ascorbic acid, quercetin trisaccharide, quercetin-3-O-rutinoside, beta-carotene, and potassium) compared with untreated control plants. The minimal environmental impact and absence of any negative side-effects on growers and consumer health may encourage the use of these elicitors in organic farming and horticulture

Towards The Robust Intersection Of Implicit Quadrics

We are interested in eciently and robustly computing a parametric form of the intersection of two implicit quadrics with rational coe- cients. Our method is similar in spirit to the general method introduced by J. Levin for computing an explicit representation of the intersection of two quadrics, but extends it in several directions. Combining results from the theory of quadratic forms, a projective formalism and new theorems characterizing the intersection of two quadratic surfaces, we show how to obtain parametric representations that are both \simple" (the size of the coecients is small) and \as rational as possible"