HAT heterosis is a genetic phenomenon cannot be doubted. And yet, in spite of our awareness of this phenomenon for many years, genetic mechanisms responsible for heterosis have not been demonstrated operationally ( SARKISSIAN 1967). That is, it has not been possible to define heterosis-superior growth of a hybrid-in terms of actual operations o r experimental treatments that may have been appli...

Two field experiments were conducted in 1995-1996 to determine if there are common yield responses among maize hybrids to larval western corn rootworm, Diabrotica virgifera virgifera LeConte injury. Three yellow dent hybrids, five white food grade dent hybrids, and a popcorn hybrid were included in the study. The minimum level of rootworm injury as measured by root damage ratings (3.2-4.2) that...

The objectives of the present study were to determine heterotic groups of germplasm lines of tropical maize by test crosses and by simple sequence repeat (SSR) markers and to compare five grouping methods of heterogeneous maize. Sixteen lines of nine populations in the S5 generation were evaluated in test crosses with three testers. The results of four experimental trials over two years were us...

Seven maize, Zea mays L., genotypes selected for native resistance to western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), larval feeding damage (SUM2068, SUM2162, CRW3(S1)C6, NSS1 x CRW3(S1)C6, PI583927, CRW2(C5), and AR17056-16) were evaluated along with three control maize genotypes in the field for plant damage, larval recovery, adult emergence, root si...

Exposure to elevated tropospheric ozone concentration ([O3 ]) accelerates leaf senescence in many C3 crops. However, the effects of elevated [O3 ] on C4 crops including maize (Zea mays L.) are poorly understood in terms of physiological mechanism and genetic variation in sensitivity. Using free air gas concentration enrichment, we investigated the photosynthetic response of 18 diverse maize inb...

Attack of plants by herbivorous arthropods may result in considerable changes to the plant's chemical phenotype with respect to emission of herbivore-induced plant volatiles (HIPVs). These HIPVs have been shown to act as repellents to the attacking insects as well as attractants for the insects antagonistic to these herbivores. Plants can also respond to HIPV signals from other plants that warn...

In this paper, the authors evaluate the impact of access to ICT-based market information on prices received by farmers and the intensity of adoption of improved hybrid and composite maize varieties. Propensity score matching is applied to cross-sectional survey data from farmers whose major cash crop is maize. Results indicate that adoption of improved maize has a positive and significant effec...

the identification of parental inbred lines to develop superior hybrids is a rather costly and time-consuming step in maize breeding. in some cases, pedigree information has been used to select diverse parental lines. in the case of iranian maize inbred lines, this information is not fully available. in this study we investigated the genetic distance (gd) based on simple sequence repeats (ssr) ...