Yield stability and relationships among parameters in maize

Producing high yielding maize (Zea mays L.) hybrids well-adapted to many environments is the most important goal of the National Maize Research Program in Egypt. Genotype x environment interaction (GEI) continues to be a major challenging issue to plant breeders and production agronomists. The objective of this study was to identify maize hybrids with stable and high yield performance across different location under Egyptian conditions. Five yellow single crosses (SC Sk-149, SC Sk-150, SC Sk-151, SC Gm-111 and SC Gz-312); three red single crosses (SC Sk-1 Red, SC Sk-2 Red and SC Sk-3 Red); and two yellow commercial hybrids (SC 162 and SC 168) were evaluated at five sites in Egypt. Stability parameters for grain yield were performed to estimate both regression coefficient (bi), deviation from regression (S2di) and coefficient of determination (R2). Results showed that mean squares due to environments (E), hybrids (H) and their interaction (H × E) were significant, or highly significant for all traits. The best hybrids were SC Sk-3 Red for earliness, SC Gm-111 for highest plant; and SC Sk-149 and SC Sk-2 Red for resistance to late wilt disease. Superiority percentage for grain yield of two yellow promising crosses SC Gm-111 (22.78 and 19.69%) and SC Sk-150 (11.00 and 8.21%) were significantly out yielded the two checks SC 162 and SC 168, respectively. Four hybrids can be considered stable for grain yield based on the regression coefficient; as well as five hybrids based on deviation from regression and eight hybrids depending on coefficient of determination. Hybrids SC Sk-150 and SC Gm-111 had high grain yield and stable for R2. Mean grain yield was significant and positively correlated with S2di; but not significant with bi and R2. Also, R2 was significant and negatively correlated with S2di, but not significant with bi also bi or with S2di. &nbsp

DIALLEL ANALYSIS AMONG NEW YELLOW MAIZE INBRED LINES FOR GRAIN YIELD AND OTHER AGRONOMIC TRAITS

Yellow maize ( Zea mays L.) is one of the important sources of animal feed in Egypt. The national maize programmes uses conventional crop breeding methodology, which depends on the development inbred lines of maize from open pollinated varieties or other heterogeneous sources. The objective of this study was to assess the general and specific combining ability for nine yellow maize inbred lines and their crosses for grain yield and other morphological traits, under Egyptian conditions. Nine new yellow maize inbred lines, derived from different yellow maize sources, were crossed in a half diallel mating scheme in 2020 summer season, at Gemmeiza Agricultural Research Station Gharbia Governorate in Egypt. The resulting 36 crosses, along with two commercial check hybrids (SC 168 and Pioneer SC 3444), were evaluated at three locations, i.e. Gemmeiza, Mallawy and Sids Agricultural Research Stations of the Agricultural Research Center (ARC), in 2021 summer season in Egypt. Overall, the additive gene effects played a major role in the inheritance of days to 50% silking, plant and ear heights; while the non-additive gene effects were mostly responsible for controlling the inheritance of grain yield. The parental inbred lines (P1 and P2) possessed significant (P<0.05) negative estimates of GCA effects for days to 50% silking towards earliness. The best general combiners were inbred lines P2 and P6 for plant and ear height, and these inbred lines would be good combiners for breeding to short hybrids and low ear placement. Crosses (P1xP9 and P3xP4) had desirable SCA effects and significantly out-yielded the two checks.Le ma\uefs jaune (Zea mays L.) est l\u2019une des principales sources d\u2019alimentation animale en \uc9gypte. Les programmes nationaux de ma\uefs utilisent une m\ue9thodologie conventionnelle de s\ue9lection des cultures, qui d\ue9pend du d\ue9veloppement de lign\ue9es consanguines de ma\uefs \ue0 partir de vari\ue9t\ue9s \ue0 pollinisation libre ou d\u2019autres sources h\ue9t\ue9rog\ue8nes. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer la capacit\ue9 de combinaison g\ue9n\ue9rale et sp\ue9cifique de neuf lign\ue9es consanguines de ma\uefs jaune et de leurs croisements pour le rendement en grain et d\u2019autres caract\ue8res morphologiques, dans les conditions \ue9gyptiennes. Neuf nouvelles lign\ue9es consanguines de ma\uefs jaune, d\ue9riv\ue9es de diff\ue9rentes sources de ma\uefs jaune, ont \ue9t\ue9 crois\ue9es dans un sch\ue9ma d\u2019accouplement semi-diall\ue8le au cours de la saison estivale 2020, \ue0 la station de recherche agricole de Gemmeiza, dans le gouvernorat de Gharbia, en \uc9gypte. Les 36 croisements r\ue9sultants, ainsi que deux hybrides t\ue9moins commerciaux (SC 168 et Pioneer SC 3444), ont \ue9t\ue9 \ue9valu\ue9s \ue0 trois endroits, \ue0 savoir les stations de recherche agricole de Gemmeiza, Mallawy et Sids du Centre de recherche agricole (ARC), au cours de la saison estivale 2021 en \uc9gypte. Dans l\u2019ensemble, les effets additifs des g\ue8nes ont jou\ue9 un r\uf4le majeur dans l\u2019h\ue9r\ue9dit\ue9 des jours \ue0 50\ua0% d\u2019apparition des soies, des hauteurs de plantes et d\u2019\ue9pis\ua0; tandis que les effets g\ue9n\ue9tiques non additifs \ue9taient principalement responsables du contr\uf4le de l\u2019h\ue9r\ue9dit\ue9 du rendement en grain. Les lign\ue9es consanguines parentales (P1 et P2) poss\ue9daient des estimations n\ue9gatives significatives (P <0,05) des effets de la GCA pendant des jours jusqu\u2019\ue0 50\ua0% de soyage vers la pr\ue9cocit\ue9. Les meilleurs combineurs g\ue9n\ue9raux \ue9taient les lign\ue9es consanguines P2 et P6 pour la hauteur des plantes et des \ue9pis, et ces lign\ue9es consanguines seraient de bons combinateurs pour la reproduction d\u2019hybrides courts et le placement des oreilles basses. Les croisements (P1xP9 et P3xP4) ont eu des effets SCA souhaitables et ont nettement d\ue9pass\ue9 les deux contr\uf4les