Search Results
Abstract
Seven mutant strains of tomatoes, crimson (ogc), high beta-carotene (B), low total (yellow r), ‘Snowball’ (yellow r), apricot (at), high pigment (hp), ‘Jubilee’ (tangerine, t), and the check cultivar ‘Rutgers’ were surveyed to determine the effects of these fruit pigment mutants on leaf pigments. Chlorophylls a and b, beta-carotene, lutein, violaxanthin, lutein 5,6-epoxide, and neoxanthin were separated chromatographically and quantities were determined spectrophotometrically. Significant differences among strains were found in chlorophylls and beta-carotene levels. Xanthophyll differences were, generally, nonsignificant. A definite pattern of gene effects was suggested. The apricot strain produced the highest levels of chlorophylls and beta-carotene in the leaves; one of the r strains, ‘Snowball’, the lowest.
Parents, F1 and F2 generations involving apricot, yellow (low total), crimson, and normal were analyzed to determine whether these leaf pigment differences could be related to these particular genes. Apricot significantly increased chlorophyll and beta-carotene levels as suggested in the survey. Yellow in a variable background, however, did not lower these pigments significantly.
Pigment synthesis in tomato leaves and fruits was discussed in relation to the gene effects inferred in the survey and the specific gene effects demonstrated in the segregating populations.
Abstract
Comparison of corn (Zea mays L.) kernels derived from common F2 families that were homozygous sugary (su) or homozygous for an allele of brittle (bt), termed bt-A, showed that bt-A kernels germinated nearly as well as su kernels and the time period for silking was identical in the 2 classes. The bt-A gene conditions twice the sucrose level found in su kernels.
The effects of 15N-labeled fertilizer applied to mature summer-bearing red raspberry (Rubus idaeus L. `Meeker') plants were measured over 2 years. Four nitrogen (N) treatments were applied: singularly at 0, 40, or 80 kg·ha-1 of N in early spring (budbreak), or split with 40 kg·ha-1 of N (unlabeled) applied at budbreak and 40 kg·ha-1 of N (15N-depleted) applied eight weeks later. Plants were sampled six times per year to determine N and 15N content in the plant components throughout the growing season. Soil also was sampled seven times per year to determine inorganic N concentrations within the four treatments as well as in a bare soil plot. There was a tendency for the unfertilized treatment to have the lowest and for the split-N treatment to have the highest yield in both years. N application had no significant effect on plant dry weight or total N content in either year. Dry weight accumulation was 5.5 t·ha-1 and total N accumulation was 88 to 96 kg·ha-1 for aboveground biomass in the fertilized plots in 2001. Of the total N present, averaged over 2 years, 17% was removed in prunings, 12% was lost through primocane leaf senescence, 13% was removed through fruit harvest, 30% remained in the over-wintering plant, and 28% was considered lost or transported to the roots. Peak fertilizer N-uptake occurred by July for the single N applications and by September for the last application in the split-N treatment. This uptake accounted for 36% to 37% (single applications) and 24% (last half of split application) of the 15N applied. Plants receiving the highest single rate of fertilizer took up more fertilizer N while plants receiving the lower rate took up more N from the soil and from storage tissues. By midharvest, fertilizer N was found primarily in the fruit, fruiting laterals, and primocanes (94%) for all fertilized treatments; however, the majority of the fertilizer N applied in the last half of the split application was located in the primocanes (60%). Stored fertilizer N distribution was similar in all fertilized treatments. By the end of the second year, 5% to 12% of the fertilizer acquired in 2001 remained in the fertilized plants. Soil nitrate concentrations increased after fertilization to 78.5 g·m-3, and declined to an average of 35.6 g·m-3 by fruit harvest. Seasonal soil N decline was partially attributed to plant uptake; however, leaching and immobilization into the organic fraction may also have contributed to the decline.
Abstract
New hybrids of sweet corn (Zea mays L.) utilize genes which allow the build-up of high levels of sugar but which also lead to problems with seed and seedling vigor. In this study, ATP and various seedling vigor measurements were compared with seed germination and seedling vigor in normal and 3 corn endosperm mutants harvested at 16 to 42 days post-pollination. Germination and seedling vigor measurements (germination rate, radicle length, fresh and dry weight) showed that a shrunken-2 (sh2) corn was significantly lower in both laboratory and field tests than sugary (su), brittle (bt), and normal. The latter 3 genotypes were nearly equal in seedling vigor. Sugar levels of all mutants and normal were similar at 42 days post-pollination. Total polysaccharides in sh2 were 50% or more below the other 3 genotypes. ATP levels in seeds imbibed 4 hours, were generally similar in sh2 as in the other genotypes. In a time course study of 0 to 96 hr imbibition using 42 day-old seeds, the ATP content of sh2 seeds, was generally as high or higher than in the other 3 genotypes. It did not appear that ATP level was related to poor vigor during the early stages of germination of sh2 corn seeds.
Abstract
A single recessive gene was found to be responsible for the abnormal fruit ripening of ‘Alcobaca’ tomato (Lycopersicon esculentum Mill.). This gene causes a ripening syndrome characterized by attenuated respiratory activity and ethylene production, delayed softening of the fruit, low polygalacturonase (PG) activity, and extended shelf life. Allelism tests showed that the mutant gene of ‘Alcobaca’ is allelic to nor. It is proposed that the symbol nor A be used to refer to this mutant. The nor A allele is dominant to the nor allele.