Genetic analysis of quantitative traits in diallel crosses of diverse pearl millet populations

Eleven (India) or twelve (Sudan) pearl millet parental populations and their F1 diallel crosses were evaluated in a randomized complete-block design with three replications across eight enviroments. Environments were Sudan (Wad Medani, three rainy seasons from 1996-1998, July to October), and India (Patancheru and Bhavanisagar rainy season of 1993, Patancheru summer season 1994 from January to April, and Patancheru 94-1995 rainy seasons, July to October). Observations on time to flowering, plant height, panicle length, productive tillers per plant, and grain yield were recorded. Data were analysed using Gardner-Eberhart Analysis II to determine variety and heterosis effects. Heterosis was further subdivided into average heterosis (h), variety heterosis (hi) and specific heterosis (sii) effects.. The analyses were performed for each season and across seasons for Wad Medani environment, then combined across all environments. Significant amount of genetic diversity were found among populations and population crosses for all traits, The major source of variation among genotypes (populations and crosses) were variety effects. No significant heterosis effects NO significant heterosis was detected at Wad Medani environment. Was observed at Wad Medani environment. Significant heterosis was detected for combined analysis across all environments (India and Sudan) for all traits measured except grain yield. Both additive and nonadditive effects were involved in the expression of these traits, however additive effects were more important than dominance effects. The ranking order of general combining ability for parental populations remained consistent across environments. Populations having consistently superior general combining ability and minimum crossover interaction across enviroments, for grain yield, were ICMV 91059, SenPop, ICMP 91751, and AfPop 90. ICMP 92591 and ICMP 87307 were moderately superior but showing high degree of superiority at Bhavanisagar environment. ICMV 155 exhibited very good performance in Patancheru (across years and seasons) but performed poorly at Bhavanisagar (cool, overcast, and short-day length environment). This population seems to confer specific adaptation at Patancheru environments. ICMP 87200, NWC C2, AfPop 88 and LHGP had poor performance across all enviroments and need not be included as parent materials in new broad-based populations targeting dual-purpose (grain and stover) cultivar improvement for Sudan and peninsular India. The best ranking parental populations for Wad Medani were similar to those for combined ranking across environments, except AfPop 90 which exhibited poor ranking performance and ICMP 92591 exhibited better rank for grain yield. Crosses among the pearl millet populations were characterized by low heterosis in most traits studied, and little if any advantage compared to the best-performing parental varieties. Relatively high rank correlations between grain yield and time to flowering (earliness), plant height (short plant type), and productive tillers were observed for this set of parental populations. There is a negative rank correlation between grain yield and panicle length. Longer panicles are associated with low yield potential when there is a strong negative correlation between panicle length and productive tiller number, hence selection based on panicle length alone within this set of populations would likely have a negative impact on yield. The various traits responded differently to changing environments. Time to flowering and panicle length were the most consistent traits across environments with the largest ratiios of genotype to GxE interaction effects. Similarly, the parental populations differed with respect to heir contribution to the GxE interaction effects. Parental populations having greater degree of stability in performance per se and in hybrid combination across environments were ICMP 91059, SenPop and ICMP 91751 (good) and NWC C2, AfPop 88 and LHGP (poor). Other parental populations were responsible for the significant GxE interaction effects for each trait, which occurred due to great changes in parental population rank orders for general combining ability effects across seasons. Parental populatiions ICMV 91059, ICMP 91751, SenPop ICMV 155, and ICMP 92591 (Lubasi) consistently ranked as the better combiners for grain yield per day across all three seasons at Wad Medani, and were also the lbest combiners for earliness, shortness, and number of productive tillers