senshu.rice {agridat} | R Documentation

## Multi-environment trial of rice, with solar radiation and temperature

### Description

Response of rice to solar radiation and temperature

### Format

A data frame with 40 observations on the following 7 variables.

`country`

  country

`loc`

  location

`year`

  year of planting, last two digits

`month`

  month of planting

`rad`

  solar radiation

`mint`

  minimum temperature

`yield`

  yield t/ha

### Details

Minimum temperature is the average across 30 days post flowering.

Opinion: Fitting a quadratic model to this data makes no sense.

### Source

Seshu, D. V. and Cady, F. B. 1984. Response of rice to solar radiation and temperature estimated from international yield trials. Crop Science, 24, 649-654. http://doi.org/10.2135/cropsci1984.0011183X002400040006x

### References

Walter W. Piegorsch, A. John Bailer. (2005) Analyzing Environmental Data, Wiley.

### Examples

    data(senshu.rice)
    dat <- senshu.rice

    # Model 1 of Senshu & Cady
    m1 <- lm(yield ~ 1 + rad + mint + I(mint^2), dat)
    coef(m1)

    # Use Fieller to calculate conf int around optimum minimum temp
    # See: Piegorsch & Bailer, p. 31.
    # Calculation derived from vegan:::fieller.MOStest
    m2 <- lm(yield ~ 1 + mint + I(mint^2), dat)
    b1 <- coef(m2)[2]
    b2 <- coef(m2)[3]
    vc <- vcov(m2)
    sig11 <- vc[2,2]
    sig12 <- vc[2,3]
    sig22 <- vc[3,3]
    u <- -b1/2/b2
    tval <- qt(1-.05/2, nrow(dat)-3)
    gam <- tval^2 * sig22 / b2^2
    x <- u + gam * sig12 / (2 * sig22)
    f <- tval / (-2*b2)
    sq <- sqrt(sig11 + 4*u*sig12 + 4*u^2*sig22 - gam * (sig11 - sig12^2 / sig22) )
    ci <- (x + c(1,-1)*f*sq) / (1-gam)
    plot(yield ~ mint, dat, xlim=c(17, 32),
    main="senshu.rice: Quadratic fit and Fieller confidence interval",
         xlab="Minimum temperature", ylab="Yield")
    lines(17:32, predict(m2, new=data.frame(mint=17:32)))
    abline(v=ci, col="blue")

[Package agridat version 1.16 Index]