Maize is now widely grown in containers in greenhouses to facilitate phenotypic analysis. Fe chlorosis regularly occurs in maize cultivars (both field and sweet maize cultivars) with fertilization and irrigation practices that result in dark green
Christopher Parry and Bruce Bugbee
Orapin Kerdchoechuen, Natta Laohakunjit, Sasathorn Singkornard and Frank B. Matta
The maize weevil Sitophilus zeamais (Motschulsky) is a major pest of stored rice and other grains ( Asawalam et al., 2008b ). In addition, the maize weevil is difficult to control, especially because the treated grain is the marketable product
B. G. Cobb, D. L. Andrews, D. M. MacAlpine, J. R. Johnson and M. C. Drew
We have been examining the response of maize seedling roots to oxygen stress. Previously, we have shown that maize seedlings with primary root lengths of 10cm or greater require a pretreatment with low oxygen (hypoxia) for survival of greater than 12 hours of anoxia. During the pretreatment there is induction of mRNA and increase in enzymatic activity of alcohol dehydrogenase (ADH) and other enzymes that are necessary for alcoholic fermentation. However, we have found that younger seedlings do not need a pretreatment to survive anoxia. They appear to have high levels of ADH and other enzymes that are needed for anaerobic survival at levels equivalent to those that are induced in older seedlings. These results suggest that, at the time of seedling emergence, seedlings may be more adapted to oxygen stress than during later stages of growth.
Igenicious N. Hlerema, Bahlebi K. Eiasu and Susan H. Koch
maize plant material and to establish the levels of Cd in the oyster mushrooms produced on Cd-contaminated pineapple crop residue. Materials and Methods Experimental site description. The experiments were conducted at the Plant Protection Research
Mwanarusi Saidi, Francis M. Itulya, Joseph N. Aguyoh and Mathieu Ngouajio
compatible as an intercrop with maize, millet, sorghum as well as with several plantation crops ( Singh and Emechebe, 1998 ). These characteristics have made cowpea an important component of subsistence agriculture in the semiarid tropics of Africa, Latin
Paul H. Jennings, N. Ishii and R. Rufner
Chlorotic bands across sugarcane leaves were first described as symptoms of cold chlorosis in 1926 and later described in sorghum and maize. The injury develops after exposure of seedlings to temperatures in the 0°C to 12°C range. The severity of injury in maize seedlings may be reduced by high relative humidity during the post-chilling period suggesting a temperature induced water stress. An early visible chilling response is the appearance of a glazed area in the region in which the chlorotic band will develop. This area of the young expanding maize leaf was studied with scanning electron microscopy(SEM). Maize seedlings were grown for 6 days at 24°C with a 15/9 h light/dark cycle. Plants were chilled at 10°C for 9 h during the 7th dark period and leaves sampled 39 h after the end of chilling. SEM photomicrographs revealed a gradient of epicuticular wax deposition from the tip to the base of the leaf. In the region of chill-induced chlorotic band formation, the control leaves exhibited a greater amount of wax deposition than the chilled leaves. It is suggested that the reduced epicuticular wax in a band across the chilled leaves might lead to a water stress resulting in chlorosis and eventually developing into the typical necrotic band.
Xiao-Fang Huang, Binh Nguyen-Quoc and Serge Yelle
Sucrose synthase (SS) is one of the key enzymes in plant carbohydrate metabolism. In maize, this enzyme is encoded by two genes, Sh1 and Sus1. We have isolated and determined the 5'-upstream sequence of maize Sus1 gene and compared it with the corresponding sequence in Sh1 gene. Sequence analysis revealed that there was a weak homology between the two promoters and no common sequence elements were found. To understand the differential regulation of the expression of the two genes, we constructed chimeric GUS fusions using the two promoters of SS genes. By using the biolistic system, we delivered these constructs into various plant tissues, and their transient expression was studied. Our results showed that the two promoters of SS genes directed tissue-specific expression in the same way that the two genes are expressed in vivo. The effectiveness of the expression of the constructs was recorded by counting the total blue expression units (blue spots) per shot and by fluorometric assays. High levels of GUS activity were detected in the immature embryos, young coleoptiles, and heterotrophic young leaves bombarded with the Sus–GUS construct. More than 100 expression units were observed in these tissues. Compared with the transient expression of the 35S promoter in the same tissue, Sus promoter activity was twice as high. Strong Sus–GUS expression was also detected in the aleurone cells of developing kernels. In contrast, the Sh-GUS construct was expressed only in the endosperm with an activity twice as high as that of Sus–GUS and 35S–GUS in the same tissue. The results will be discussed in terms of the physiological roles of the two SS isozymes in plant tissues.
Martin M. Williams II
increase in hybrid maize yield over the last 75 years ( Duvick, 2005 ). Although sweet corn is planted across a range of dates, most research on planting date effects on maize growth and yield response have been conducted in dent corn. In comparison of
K.G.V. Davidson, F.D. Moore III and E.E. Roos
Multiple electroconductivity readings (μAmps) of leachates from individual seeds during the first 6 hr of imbibition was examined as a possible predictor of seed quality. Readings from each sample of 100 seeds were formed into frequency distributions and the mean, median. and internal slope were calculated using an automated computer retrieval system. Internal slope is a non-central tendency measure based on the slope of a line tangent to the inflection point of the S-shaped cumulative frequency distribution (CFD) of μAmps. Radicle lengths (3 days) and germination (7 days) percentages were regressed on each of the two measures of central tendency and also the CFD shape indicator, internal slope. None of the three predictors were satisfactory for estimating seed vigor (root lengths) of maize (Zea mays L.) or wheat (Triticum aestivum L.) or germination of wheat seed lots. Internal slope was useful in estimating viability of artificially aged maize seeds (r2= 0.91), which compared favorably with our previous results using naturally aged red clover (Trifolium pratense L.) seed lots. Overall the seed quality of the unaged wheat lots was fairly high and the electrolyte leakage test was not sensitive enough to detect differences within these lots.
Luz M. Reyes, Orlando Martinez and Nubia Martinez
Variability of `chococito' maize cultivars (Zea mays L.), have been decreased in the Anchicaya river area, because new crops were established there. Process of recuperation, promotion, and conservation under in situ and ex situ conditions were proposed to the community of the area. Using participatory research methodologies, memory and uses were recuperated for four varieties through the Exchange Seed Interchange Fund (ESIF), established just for maize. The study was carried out in two components: social and agronomic. The social component was development in three phases: i) diagnosis; ii) establishment of the ESIF, and iii) socialization. The agronomic characterization was performed with members of the community through the development of the crop. Twenty-six variables, both quantitative and qualitative, were registered. The cultivars were appropriated for extreme conditions of the Anchicaya river area, high temperatures (30 °C) and high level of precipitation (6000 mm/year). During the process of cropping, it was found that the “to cut and to decay” system is the most common used in this region. Using multivariate analyses of quantitative and qualitative variables, the relationships between materials of `Chococito” race were found. The dendograms for these cultivars had shown differences among them. As a complement of the in situ conservation done by compromise of the Anchicaya's community, a duplicate under ex situ conditions was established at the Genetic Resources Laboratory, belonged to the Agronomy Dept. of National Univ. of Colombia.