International Journal of Material and Mechanical Engineering (IJMME), Volume 4, 2015 www.ijm‐me.org doi: 10.14355/ijmme.2015.04.001
Stability of Grain Yield of Maize Hybrids in Eight Environments in Mali Coulibaly Mamadou Mory*1, Niaba Teme2, Essie Blay3, Vernon Gracen4, Late the Charles5 CRRA Sotuba maizeprogramme IER BP 262 Bamako Mali *1madoumory@yahoo.fr; 2niabateme@gmail.com; 3essie_blay@hotmail.com; 4v45@corneil.edu
Abstract Maize is produced in varying environment dictating yield performance and stability in Mali. To validate yield and stability performance, 78 hybrids and 2 checks were tested across eight environments at six sites in Mali during the rainy season of 2011. Two planting dates were used in Sotuba and Siramana locations to create additional environments. The hybrids were evaluated in Randomized Complete Block Design with two replications for one year. The objectives were (1) to study the nature and the magnitude of the genotype x environment interaction and (2) the grain yield stability within and across environments. Sotuba 1, Sotuba 2, Kebila and Kafara were high yielding environments characterized by better performance and very high yield. Siramana 1, Siramana 2, Tamala, and Koulikoro were low yielding environments which was determined with GGE biplot analysis. Nine hybrids were stable across the high yielding environments. Across the low yielding sites, twenty two hybrids exhibited stable performance. Seven Inbred lines showed positive GCA in high yielding environments indicating a predominance of additive gene action. The best SCAs were obtained with P43SRC9FS100‐1‐ 1‐8/V481‐73, CML442/87036 and (KU1403x1368)/CML505. The hybrid with the best SCA value P43SRC9FS100‐1‐1‐ 8/V481‐73 was from parents exhibiting the highest GCA values. Keywords Diallel; Combining Ability; Stability
Introduction In sub‐Saharan Africa, maize (Zea mays L.) is the most important cereal crop but the average yield is very low (1.3 tha‐1). In Mali, maize is a staple food crop for an estimated 50% of the population. Most Malians consume maize as a starchy staple in a wide variety of porridges, pastes, and beer. Green maize (fresh on the cob) is eaten roasted or boiled and plays an important role in filling the hunger gap after the dry season (IITA 2007). In Mali, the minimum maize grain yield ranged from 1 tha‐1 in 2000 to 1.5 tha‐1 in 2008 which is very low compared to the 7 tha‐1 obtained in North America in 2000 (IOWA 2002) . Drought is one of the major limiting factors for maize production followed by the parasitic weed, Striga hermonthica. Annual maize yield losswas 12% from drought stress in the savanna of West and CentralAfrica (WCA) (Waddington et al., 1995). Losses can even be greater if the stress occursat the most drought‐sensitive stages of crop growth, such asflowering and grain filling periods (Denmead and Shaw 1960, NeSmith and Ritchie 1992). Average annual production growth rate of maize for the period 1983‐1992 was 7.5% due primarily to an increase of 6.6% in the land area devoted to maize production (CGIAR 1997). Crop performance increases from north to south according to a general gradient of rainfall and soil fertility (Figure1). In order to respond to varying climatic conditions, varieties with different characteristics (drought tolerance, early maturity) must be developed. The national research institute (IER) has released improved OP varieties such as Dembanyuman and Sotubaka that are adapted to the area where the rainfall is above 800mm per annum. IITA has also developed early (90 day maturity) and extra early (80 day maturity) OP varieties. Despite these efforts, maize productivity is low and depends on rainfall levels. Varieties which are higher yielding and stable under low rainfall conditions are needed. An important way of increasing maize productivity and production is the exploitation of hybrid vigor under drought conditions. Hybrids are usually characterized by high vigor or heterosis that occurs when two genetically unrelated inbred parents are crossed. Hybrids out yield and are more stress tolerant than OP varieties. During the cropping season of 2002‐2003, 17 maize hybrids (originated from South Africa) were tested at the IER’s
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