Effect of population densities of Heterodera ciceri on new resistant lines of chickpea
AbstractAn experiment was undertaken in Syria to assess the effect of increasing population densities of Heterodera cicai on yield and protein content of three new lines of chickpea resistant to the nematode (NEMR-13, NEMR-14, NEMR-15) and of their susceptible (FLIP 87 -69C) and resistant (IL WC 292) parents. The effects of these lines on the reproduction of the nematode and soil nitrogen content were also investigated. The experiment was set in the field in microplots of 26 cm diameter and 55 cm depth. Population densities of 0,0.5, 1,2,4,8, 16,32,64 and 128 eggs/cm3 soil were used for the experiment. Symptoms of nematode attack appeared earlier and at smaller population densities on susceptible parents than on resistant lines. Tolerance limits of the lines FLIP 87-69C, ILWC 292, NEMR-13, NEMR-14 and NEMR-15, respectively, to the nematode were: for grain yield 0.4,0.9,1.3,1.3 and 1.6 eggs/cm3 soil; for biomass 0.4,1.1,1.3,1.2 and 1.4 eggs/cm3 soil; for grain protein content 1.19, 1.3, 1.25, 1.1 and 1.1 eggs/cm3 soil. For the same lines, minimum relative grain yields were: 0, 0.09, 0.1, 0.06 and 0.03; minimum relative biomass was 0.02, 0.11, 0.15, 0.1 and 0.1; and minimum relative protein content was 0.65, 0.75, 0.87, 0.9 and 0.85. The nematodes reproduced more on the susceptible parents than on the resistant parents and new resistant lines, with maximum reproduction rates of 69-fold on the susceptible line and 6.8-fold on the new lines. The nematode equilibrium densities were 45 eggs/cm3 soil on the susceptible line and 28.7 eggs/cm3 soil on the resistant lines. In general, eggs per cyst and per cent of new cysts were more in plots sown to the susceptible line than in those sown to resistant lines.