Yi = a + be
where: Yi = yield of variety i, and
 e = environmental index equal to the average
 yield of all treatments at each location

By fitting the equation independently for each variety,
then plotting the yield response to environment for each
variety on the same graph, it is possible to visually
compare varieties. Using the same procedure, it is easy
to generalize these equation sets to any number and kind
of treatments.


TABLE VII-3.


Maize yield from farmer-managed, on-farm
trials, Phalombe, Malawi, 1981/1982.


 Farmers in first village
Trts 1 2 3 4 5 6 7 8 TMV
 t/ha

LM 2.2 2.2 1.9 1.2 1.3 0.9 1.0 0.5 1.4
LM-F 3.6 3.7 4.3 3.2 2.3 2.3 3.1 2.8 3.2
CCA 3.5 2.0 2.9 0.4 0.6 0.5 0.6 0.3 1.3
CCA-F 5.0 4.7 4.3 3.5 2.4 1.7 3.0 2.8 3.4
MF = ei 3.6 3.2 3.3 2.1 1.7 1.3 1.9 1.6

 Farmers in second village
 1 2 3 4 5 6
LM 1.8 1.1 1.6 1.0 1.6 0.6 1.3
LM-F 3.2 2.5 2.9 1.2 1.9 0.8 2.1
CCA 2.2 0.7 0.9 0.3 1.1 0.3 0.9
CCA-F 2.9 2.5 2.1 1.1 0.8 0.4 1.6
MF = ei 2.5 1.7 1.9 0.9 1.4 0.5


Source: Hansen et
LM = Local Maize


al., 1982.


LM-F= Fertilizer Local
CCA = CCA Maize


CCA-F = Fertilizer CCA
MF = Mean for farmer
TMV = Treatment Mean
 for Village


 Data for a maize trial from the Phalombe Project in
Malawi (Hansen et al., 1982) are analyzed as an example.
Fourteen farmers from two villages participated in trials
conducted on their respective farms. A simple,
non-replicated 2 x 2 factorial arrangement with two maize