Attempts were made to estimate the area under the disease progress curve (AUDPC) of rice blast disease caused by Pyricularia grisea from two data points on the disease progress curve. Forty-two rice genotypes were exposed to high disease pressure in a nursery over nine seasons. A conducive condition was created for maximum disease development through high nitrogen application, close spacing and maintenance of high relative humidity. Disease severity was recorded on alternate days beginning from disease initiation until the end of the epidemic. The estimation of AUDPC, and logistic and Gompertz apparent infection rates using either all-points (AP) or twopoint (TP) methods revealed significant correlations among them. This was also confirmed through regression analysis and factor analysis. Hence, the estimation of AUDPC from two data points i.e. initial and final disease scores of the disease progress curves is recommended as providing information similar to that from all the data points; this should save valuable time, labour and economic resources.

The development of rice blast disease in four slow-blasting (SB) genotypes was compared with that in the fast-blasting (FB) genotype Karuna, under natural field epidemics over a period of 3 years at five levels of nitrogen, in order to determine if the application of high doses of nitrogen influenced the expression of disease progress in the SB types. The treatment effects were compared through estimation of nine parameters viz. (i) lesion number (LN); (ii) area under disease progress curve (AUDPC); (iii) relative area under disease progress curve (RAUDPC); (iv) logistic apparent infection rate (r); (v) Gompertz apparent infection rate (k); (vi) logit line intercept (logit-a); (vii) gompit line intercept (gompit-a); (viii) time required for the disease to reach 0·25 severity in logistic (T25r); and (ix) Gompertz (T25k) models. There was a significant increase in LN, AUDPC, RAUDPC, r and k with increased levels of nitrogen application in all genotypes, but the rate of increase in disease severity was much lower in SB genotypes than the FB one and did not lead to breakdown of resistance in the SB genotypes, since severity level was much below the economic injury level. Among the nine derived parameters for evaluation of resistance LN, AUDPC, RAUDPC, r and k were best. The AUDPC and RAUDPC had lower degrees of error variance compared with the other parameters and hence were considered superior measures for characterization of disease progress curves.

The diazonium salts of aniline and 4,4Ј-diaminodiphenylmethane coupled with phenol and resorcinol were condensed with formaldehyde in alkaline media to yield polymeric resins. These polymers were found to readily react with metal ions like Cu 2ϩ and UO 2 2ϩ , forming polychelates. The azodyes, resins, and polychelates were characterized by several instrumental techniques such as elemental analysis, FTIR, 1 H-NMR, GPC, XRD, TG-DTG, and DSC studies. The chelating capacity of the resins toward Cu 2ϩ and UO 2 2ϩ ions was studied by spectrophotometry. The extent of metal loading of the resins was studied by varying the time of contact, metal-ion concentration, and pH of the reaction medium. The alkali and alkaline earth metal ions had little effect on the metal-ion uptake behavior of the resins. The resin derived from the azodye of 4,4Ј-diaminodiphenylmethane was found to be more efficient in removing the metal ions from solution than were the resins from aniline. The optimum conditions for effective separation of Cu 2ϩ from UO 2 2ϩ were determined.