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The analysis of lattice designs with varieties showing a linear response to levels of some factor confounded with replications is described and illustrated with a hypothetical example. The theory is applied to a 7✕7 quadruple lattice maize (Zea maysL.) variety trial with replications of the lattice planted at different plant densities. A linear regression model is used which assumes that the yield of each variety expressed as log (yield/plant) responds linearly to plant density. In a manner analogous to ordinary lattice designs, corrections for block differences to be applied Jo variety means and regression coefficients are obtained. Two methods of adjusting for variable stands, viz., covariance analysis with deviation from average stand at) a given plant density level as the covariable (Method I) and adjustment of the raw data using preliminary estimates of the variety regression coefficients (Method II), are suggested and compared with a generalized least squares solution (Method III). Method III is the theoretically correct procedure but we consider it impractical for large experiments. Both Methods I and II gave good approximations to the results for Metlfod III. The experiment showed significant differences among variety means and among variety regression coefficients. Information on varietal response to plant density is obtained at the cost of very little loss of precision on variety means. It is suggested that for equivalent varietal replication more comprehensive yield trial data could be obtained by evaluation at more plant density levels with less (or possibly no) replication ot each density.

A continuing deterrent to increased use of N fertilizers on humid‐zone grasslands is the possibility of deleterious nutritive effects resulting from ingestion by animals of herbage high in nitrate. Studies were initiated to obtain data on the pattern of NO3‐N accumulation and disappearance in Kentucky bluegrass (Poa pratensisL.) and tall fescue (Festuca arundinaceaSchreb.) herbage following spring fertilization with four levels of N. Identical experiments of split‐plot design were conducted on adjacent areas of the two grasses. Ammonium nitrate was applied to supply 50, 100, 150, or 200 kg/ha of N. The N treatments were replicated hi time, with a spacing of 3 weeks between replications. Herbage samples were collected at weekly intervals for a period of 6 weeks following fertilization. Dry matter yields and concentration of total N and NO3‐N in the herbage were determined. The pattern of accumulation and disappearance of NO3‐N appeared to be similar for the two grasses. Accumulation peaks were almost always reached within 14 days following fertilization, after which the values gradually declined. Length of time required for dissipation of the effect of N application on NO3‐N levels was directly related to quantity of fertilizer used but also appeared to be dependent on the species of grass. In two of the three growth periods, for example, the concentrations of NO3‐N in Kentucky bluegrass receiving 200 kg/ha of N decreased to values below 2,000 ppm within 4 weeks after fertilization. In contrast, tall fescue herbage consistently contained 2,000 ppm or more of NO3‐N 6 weeks after fertilization at the 200 kg/ha rate. Coefficients of variation for ppm of NO3‐N were 22.5% for Kentucky bluegrass and 21.1% for tall fescue; the C.V. for percent total N was 4.4% in bluegrass and 4.3% in fescue. Peak NO3‐N levels and maximum total‐N values occurred at essentially the same time. Some implications of the findings are discussed with respect to utilization of N‐fertilized grasslands and the use of herbage NO3‐N levels for predicting response of grasslands to N fertilization.

Discusses the findings of a study conducted by researcher Joanne A. Byars and colleagues, which found the effectiveness of naltrexone for smoking cessation in women in conjunction with nicotine replacement therapy and psychosocial therapy in Florida. Total number of subjects who participated in the study; Assessment of the participants' level of nicotine dependence; Benefits of naltrexone on women.