CHARACTERISTICS OF THE INCOMPLETE RESISTANCE OF HORDEUM CHILENSE TO THE ROOT-KNOT NEMATODE MELOIDOGYNE-NAASI FRANKLIN - DESCRIPTION OF A NEWLY CONCEIVED TEST TO DETECT THE RESISTANCE

We are able to describe, due to some assays conducted under field conditions, the different ways the root-knot nematode of cereals was affected in some amphiploid plants carrying the resistance of a wild Hordeum sp. This resistance arises in one of three ways: (i) a reduction in the establishment of the infective juvenile stages in the root, (ii) a delay and/or a cessation of development of the parasite occurring at the J2 or swelling-J2 stage, (iii) an altered fecundity of the females. These three actions efficiently control the multiplication of the nematode, resulting in few females at the end of growing period of the crop. A new test was developed for early screening of the resistance under controlled conditions. Based on the analysis of the gall rating and the contents of five young galls from each plant, the response of a line can be seen within 16 days, while preserving the viability of the plants to continue their growth.