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Abstract
‘Pennfresh ADX’ is a high-sugar sweet corn hybrid (Zea mays L.) based on the recessive endosperm gene combination amylose-extender (ae) dull (du) waxy (wx). The effects of this gene interaction on starch and sugar properties were reported by Creech (1). This hybrid can be harvested over a longer period than traditional sweet corns which are homozygous for the sugary (su) gene, and it retains its quality much longer following harvest. The symbol ADX is derived from these 3 gene names and is used to delineate this new class of sweet corn hybrids.
Abstract
Starch granules were extracted from maize (Zea mays L.) endosperm of mature F2 kernels of IA5125 × IA453 normal, amylose-extender (ae), dull (du) waxy (wx), and ae du wx and from ae du wx F2 kernels harvested at the fresh market stage of development. Samples were digested for 1.5 hours with hog pancreatic α- amylase and Rhizopus II amyloglucosidase. The mature and immature ae du wx samples were usually digested significantly more than the other 4 genotypes, while ae was digested significantly less than the others. Digestion of starch granules from mature and immature ae du wx kernels did not differ. The sweet corn background used had little effect, since our observations of the single mutant genotypes were similar to those in a dent background. Clearly, ae du wx starch granules do not reflect the reduced digestibility associated with ae, and thus cultivars homozygous for ae du wx are not inferior with respect to their ability to supply carbohydrates to the diet.
Abstract
Inheritance of the ability of tomato (Lycopersicon esculentum Mill.) to sprout at 10°C was evaluated in a diallel study involving 7 inbred parents. For each parental and F1 progeny family, sprouting indices were used to estimate genetic and environmental components of variation. Significant additive gene effects with partial dominance for inability to sprout at low temperature were found. Epistatic gene effects were not important, but a significant maternal effect was found. The estimate of narrow sense heritability was 69% and that for broad sense heritability was 85%.
Abstract
In a broad sense, fresh-market vegetable corns include all maize harvested and eaten fresh while the kernels are tender and before all of the sugars are converted to starch. This definition includes “roasting ears” of selected field corns that lack sweetness-enhancing genotypes and are considered “starchy”. Traditionally, however, sweet corn cultivars have been homozygous for the recessive sugary (su) gene (8).
Abstract
The T5125 × 1453’ hybrids of maize (Zea mays L.) homozygous for the sugary (su), amylose-extender (ae) dull (du) waxy (wx) and ae wx genotypes plus the related shrunken-2 (sh2) commercial hybrid were compared for processing and fresh market characteristics. Sensory panel evaluation and U.S. Department of Agriculture grading showed that both the ae du wx and sh2 genotypes produced high quality canned and frozen products. The processed sweet corn (su) hybrid had a high pericarp content resulting in lower quality. The ae wx canned and frozen products scored low in texture and flavor and were unacceptable. Kernel sucrose values (percent dry weight) in unstored ears were 36.5% for sh2 , 24.8% for ae du wx, 18.5% for ae wx, and 14.4% for su. Only minor changes were observed in reducing sugar, sucrose, water soluble polysaccharide (WSP), and starch measured after 24, 48, and 96 hours of storage at 4°C. After 96 hours of storage at 27°, sucrose content decreased from initial levels by 83% in su, 67% in ae wx, 63% in sh2 , and 55% in ae du wx. In spite of these decreases, ae du wx and sh2 sucrose content after 96 hours at 27° was almost as high as that found in unstored su ears demonstrating superior postharvest sugar retention for ae du wx and sh2 . Corresponding with the decrease in su sucrose during storage at 27°, WSP increased and the starch decreased. In contrast, starch increased in sh2 and tended to increase in ae du wx while WSP declined. The processing, carbohydrate, and postharvest storage data indicate that the ae wx T5125 × 1453’ hybrid cannot be used for sweet corn quality improvement, while ae du wx and sh2 show definite potential for processing use. Furthermore, ae du wx can be considered as a high sugar genotype for fresh market use along with currently grown sh2 hybrids.