Effect of Rice yellow mottle virus, Sobemovirus on the Contents of N P K Ca and Mg in Leaves of Infected Rice

ABSTRACT

Rice (Oryza spp) is one of the most important crops produced in the world. Rice production is dampered by environmental and biological factors including mainly pathogens, such as Rice yellow mottle virus (RYMV), which is the most rice devastating viral disease in Africa whereas, These factors can be overcome by using different methods such as mineral fertilization supplying. To identify nutrients for this constraint management, a study was carried out in controlled condition in a greenhouse situated at Felix Houphouët-Boigny University station at Bingerville. The rice variety named Bouake 189 was sown in pots using local soil as substrate. Fourteen days old seedlings were inoculated mechanically with isolate of RYMV. Fertilizers N, P, K 12, 24, 18 (200 kg/ha) and 100 kg/ha of urea (46% N) were applied respectively. The concentrations of N, P, K, Ca and Mg as well as protein content in leaves were determined likely. Chlorophyll measurement was obtained using Spad-505. The severity and the (AUSPC) of the RYMV were evaluated. The presence of the RYMV in the infected leaves was confirmed by serological analysis. The averages of the various parameters were compared by ANOVA 2 with software STATISTICA version 7.1. Results showed significant difference (p < 0.001) between the seedlings according to infection levels and highest concentrations of P (0.40%), K (1.10%), Ca (1.49%), Mg (0.39%) and chlorophyll (37.37) were recorded in the leaves of non-infected seedlings whereas those related to infected seedlings were of 0.39%; 0.75%; 0.67%; 0.24% and 21.23 respectively. This was contrasting with N and protein contents recording 2.41% and 15.04 for the inoculated plants and 1.75% and 10.95 for the healthy plants respectively. The average severity and viral load of Rice yellow mottle disease were reduced respectively from 6.22 to 3.88 and from 2.132 to 1.577 under the action of the mineral fertilization (NPK), hence improving rice growth and yield to be targeted.