RA 00110.pdf - OAR@ICRISAT

Pearl Millet Regional Trials by CILSS, 1981-1984
(Essais regionaux du mil conduits par le CILSS 1981-1984)
G. Loynet, A. Kere, and O. Sidibe
Institut du Sahel, CILSS, Bamako, Mali
Superior pearl millet varieties grown in the Sahelian region were evaluated from 1981 to 1984 as part of the
Crop Improvement Project for pearl millet, sorghum, cowpea, and maize, directed by the Institut du Sahel.
The best varieties were identified for different climatic situations extending from Chad in the east to Senegal
and the subdesert, Sahelian, and Sudano-Sahelian Zones in the west. The varieties were grouped geographically
by dividing the region into three agroecologically representative zones. Areas with rainfall between 200
and 600 mm are most suited to growing pearl millet; disease risks increase in high-rainfall regions.
Analysis of the International Pearl Millet Adaptation Trial (IPMAT)
(Analyse de l'Essai international du mil—objet adaptation (IPMAT))
J.R. Witcombe
Principal Plant Breeder, Pearl Millet Group, ICRISAT, Patancheru, Andhra Pradesh 502 324, India
The International Pearl Millet Adaptation Trial ( I P M A T ) , which includes both hybrids and varieties as
entries, has been grown multilocationally in India and Pakistan. The grain yield data over 5 years have been
analysed in a number of ways.
A regression analysis indicated that the breeder's procedure of selecting from among the highest-yielding
entries across environments is satisfactory, as it also selects entries that perform well in poor environments.
Selecting entries on predicted performance in the lowest-yielding environment appears to be a less reliable
procedure.
The hybrids are generally higher-yielding than the varieties, but are less stable. The most important source
of genotype x environment interaction in the regression analysis was due to the deviation from the regressions
(S 2 d values), rather than variation between the regressions. The varieties were superior to the hybrids in this
respect, with lower than average S 2 d values.
A mean-standard deviation analysis showed that the highest-yielding genotype would always be preferred
by the average, risk-averse farmer.
Discussion
Because composites may have high levels of variability, the suggestion was made to derive varieties by random
mating a few selected progenies from the composite rather than using the composite itself as the finished
product. It was pointed out that a few selection cycles in a diverse composite may result in reduced variability,
so that the composite can be tested as the finished product.
It was suggested that analysis of variance and t-test may be better methods than regression analysis for
stability analyses. Nearest neighbor analysis (NNA) and lattice designs were also suggested. In reply it was
pointed out that mean-standard deviation analysis was proposed as a better alternative to conventional
regression analysis, and that N N A and lattice designs were impractical for across-location analyses.
The comment was made that stability can be a property of individual genotypes. Varieties appeared to be
more stable than hybrids for s 2 d values but this could be the result of a statistical artifact of the regression
analysis.
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