Rice plant resistance to blast and gibberellins content in them

Blast is one of dangerous fungal diseases. Its causal organism is fungus Pyricularia oryzae cavara. Losses from this pathogen are big - 30% even at weak infestation. When plant is infested before footing, leaf form of disease is developing. Light gray spots appear, and at big damage the plants dry before fruit bearing. After footing fungus infests culm nodes and beginning with heading it infests all parts of panicle and spikelet and flower glumes. When stem nodes are infested, panicles dry and do not form grain or form weak grain. In such situation the main orientation in breeding is evaluation of initial stock for resistance to pathogen m laboratory conditions, at the level of sprouts. Creation of artificial intention background at the possibility to obtain more precise and quick evaluation of rice samples for blast resistance by amylolitic enzymes - amylases M leaf plates, initiated by gibberellin acid; it can be supposed that at high phytohormone level, resistance to pathogens will be less and vice versa. Actually, as laboratory investigations showed disease intensity (%), evaluated by amylase intensity is lower of varieties with less level of endogene gibberellins: Vodolei - 18%, Zhemchug - 14%, Khazar - 18%, Liman - 28%. Disease intensity is higher for varieties with higher phytoliormones level: VNIIR - 18-60%, Regul - 46%, Rapan - 52%. Field experiments by determination of panicular intensity of disease development are analogous to laboratory data. Other words, by amylase activity determined in leaf plates of rice spouts, it is possible to give preliminary information on résistance of rice varietal samples to pathogens. (Résumé d'auteur