Browse
You are looking at 101 - 110 of 41,729 items for
The purpose of this study was to examine the ability of preschool gardening programs to help children develop their ability to delay gratification. Children today face many opportunities for instant gratification, although the ability to delay gratification in early childhood has been linked to numerous benefits later in life. Opportunities to train children in the ability to delay gratification present educational challenges, in that it competes with other academic training needs, and it can be difficult to find programs that are interesting to young children. The population for this study was preschool children ranging in age from 2 to 6 years, with treatment and control groups drawn from different schools. Participants were tested individually and timed to determine their ability to delay gratification, with promises of larger rewards if the child could wait for 15 minutes. The results of this study did not identify a significant change in all children’s ability to delay gratification after a gardening program. However, analyses showed that females appear to have responded more positively to the gardening treatment in their ability to delay gratification, whereas males in the control group benefited more from traditional school lessons.
Drought is one of the major environmental challenges constraining the production of agricultural crops, including carrot. Seed germination is the initial and most critical stage of crop establishment, and it is very sensitive to drought stress because water scarcity affects the enzymatic solubilization of stored metabolites in seeds that provide energy for the growth of germinating embryo. Few studies evaluating the effect of drought stress on carrot seed germination of more than a few cultivars grown under stress have been published. Therefore, the present study was designed to define the appropriate osmotic potential for evaluating drought tolerance of carrot, evaluate the response of diverse carrot germplasm to drought stress during seed germination to identify drought-tolerant accessions that may be used by plant breeders, and evaluate the relation between amylase activity and germination rate of drought-tolerant and drought-sensitive accessions. To identify an appropriate screening osmotic potential, two commercial cultivars and two United States Department of Agriculture inbreeds were evaluated at six osmotic potentials (00, −0.30, −0.51, −0.58, −0.80, and −1.05 MPa); −0.58 MPa was identified as the optimal osmotic potential for screening the drought tolerance of carrot seed. Cultivated and wild carrot plant introductions (PIs) (n = 200 and n = 50, respectively) from the National Plant Germplasm System were evaluated for drought tolerance under nonstress and simulated drought stress conditions (00 MPa and −0.58 MPa, respectively) by calculating the absolute decrease (AD) in percent germination, inhibition index (II), relative drought tolerance (RDT), and drought tolerance index (DTI). All measurements of drought tolerance identified significant differences among accessions; the AD in seed germination ranged from 0.0% to 69.3%, II ranged from 0.0% to 80.2%, RDT ranged from 0.2 to 1.0, and DTI ranged from 0.13 to 1.47. All wild carrot accessions displayed low levels of drought tolerance, but PI 652387 and PI 177381 (both from Turkey) and PI 274297 (Pakistan) were most drought-sensitive, whereas cultivated accessions PI 643114 (United States), PI 652208 (China), and PI 502347 (Uzbekistan) were most drought-tolerant. Tolerant accessions displayed much higher α-amylase activity under nonstress conditions than sensitive accessions, and α-amylase activity of tolerant accessions was also reduced less with seed germination under increasing osmotic potential (range, 0.0 to −1.05 MPa) than sensitive accessions over 24, 48, and 72 hours of seed germination. This is the first evaluation of drought stress tolerance during seed germination and the enzymatic response of diverse carrot germplasms under simulated drought stress.
Agrobacterium rhizogenes transformation is a more rapid method of obtaining transgenic and edited rubber dandelion (Taraxacum kok-saghyz) plants than Agrobacterium tumefaciens. The hairy root rol genes are present alongside transgenes after transformation, and they change the morphology of rubber dandelion significantly. Although these rol genes are useful visual markers indicating successful transformation of rubber dandelion, they modify the phenotype induced by the target transgenes and are ultimately detrimental to agronomic traits. Fortunately, the rol genes can be removed by conventional plant breeding because they segregate in progeny separately from the targeted transgenes. However, it is preferable to have preliminary identification of promising effects induced by transgenes or gene edits before rol gene removal so that only the best plants are used for breeding. Therefore, the goal of this research was to characterize rol– and rol+ plant morphology so that, in the future, rol+ transgene+ plants can be easily distinguished from rol+ transgene– plants. This requires that rol gene–induced morphological changes and simply assayed physiological traits are first characterized thoroughly so that transgene changes may be observed. Taproot formation is reduced or eliminated in rubber dandelion by rol genes, and rol-induced hairy roots are identifiable easily because they grow shallowly in potting soil, so only partial unearthing is needed. Both leaf and flower numbers are increased by rol genes, but leaves and flowers are smaller than in rubber dandelion wild type with longer stalks. The rosette doming phenotype caused by the induction of a large number of leaf primordia is obvious in rooted plants as young as 1 month old. Photosynthetic rates are reduced significantly in rol+ plants, although growth is not. An accurate description of the morphology of rubber dandelion after A. rhizogenes transformation may allow for initial selection of promising transformed plants before confirmation with polymerase chain reaction, by phenotypic comparison of plants expressing transgenes and the rol gene, with those only expressing the rol gene.
Protected grape cultivation develops rapidly because of huge economic benefits. However, adverse environmental conditions (insufficient sunlight, high temperature, etc.) in protected cultivation led to low-quality berries. This study aimed to evaluate the effects of berry thinning on the quality attributes of two table grape cultivars (Baoguang and Cuiguang) under linkage greenhouse conditions. Three treatments (L, light berry thinning; M, moderate berry thinning; H, heavy berry thinning) were compared with the control (C, no berry thinning). Berry thinning increased berry weight, total soluble solids (TSS), fructose, glucose, the ratio of TSS to titratable acidity (TA), anthocyanin contents, berry firmness, and mineral contents (Ca, Fe, Na, Mg). Conversely, TA and organic acid profiles were decreased by berry thinning. Cultivars showed significant effects on most of the berry quality parameters. The interaction of cultivars by berry-thinning treatments affected sugar and acid components, anthocyanin contents, and mineral elements.
Pseudobulbs are carbohydrate storage organs in Oncidesa. A current pseudobulb forms on a developing vegetative shoot in each growth cycle and it becomes a back pseudobulb when the next vegetative shoot emerges. Both current and back pseudobulbs store carbohydrates, but their functions might differ because the inflorescence emerges from the new (current) shoot after the shoot has developed to a certain stage. This study investigated carbohydrate storage and use in current and back pseudobulbs. We analyzed carbohydrates in the current pseudobulb at five stages during inflorescence development. Glucose and fructose were the highest in the current pseudobulb in the first two stages, when the inflorescence was 10 to 35 cm tall. Then, both glucose and fructose decreased in the following stages to support inflorescence development, but starch increased at that time. In addition, we used Oncidesa with one or two new vegetative shoots to study the use of carbohydrates in pseudobulbs during growth cycles. In both plants with one or two shoots, glucose and fructose accumulated when current pseudobulbs formed, but plants with two new shoots had smaller current pseudobulbs and lower monosaccharide concentrations. Plants with two shoots also consumed more starch in all back pseudobulbs, whereas in the plants with one new shoot, starch only decreased significantly in the first back pseudobulb, which was closer to the new shoot. In addition, if an inflorescence did not develop in the previous growth cycle, new shoots used the monosaccharides that remained in the youngest back pseudobulb for growth; at the same time, starch accumulated in all back pseudobulbs. The current pseudobulb was the actively growing part. Its main carbohydrates were monosaccharides, which accounted for 25% of dry weight and Oncidesa used these carbohydrates mainly for inflorescence growth. After monosaccharides in the pseudobulb were used, the pseudobulb began to store starch. Back pseudobulbs, in which >50% of dry weight was starch, were the primary storage organs that supported new vegetative shoot growth and partly supported later inflorescence development that emerged from the new (current) shoot.
Crapemyrtle (Lagerstroemia sp.) is a top-selling deciduous flowering tree in the United States, and its salability is often compromised by cercospora (Cercospora lythracearum Heald & F. A. Wolf) leaf spot. To compare cercospora leaf spot resistance, 32 crapemyrtle cultivars belonging to Lagerstroemia indica, Lagerstroemia fauriei, L. indica × L. fauriei, and L. indica × L. fauriei × Lagerstroemia limii and 12 cultivars or unnamed selections belonging to L. indica, L. indica × L. fauriei, L indica × L. fauriei × L. limii, L. limii, and Lagerstroemia subcostata were planted in field plots in 2004 and 2011, respectively. The experiment was a completely randomized block design with three and four replications in the 2004 and 2011 plantings, respectively. Plants were evaluated for cercospora leaf spot disease severity and defoliation using a scale of 0% to 100% foliage affected from August to October of 2015, 2016, and 2017. Area under the disease progress curve (AUDPC) was calculated for the evaluation period of each year. L. fauriei cultivars Fantasy, Kiowa, Townhouse, and Woodlander’s Chocolate Soldier and L. indica × L. fauriei Apalachee from the 2004 planting, and the L. subcostata and L. limii selections from the 2011 planting had lowest cercospora leaf spot disease severity ratings, AUDPC, and defoliation. L. indica × L. fauriei cultivars Choctaw, Miami, Natchez, Osage, Sarah’s Favorite, Tonto, Tuscarora, and Tuskegee, and L. indica × L. fauriei × L. limii Arapaho were moderately resistant to cercospora leaf spot, whereas cultivars belonging to L. indica and L. indica × L. fauriei × L. limii Cheyenne were highly susceptible to cercospora leaf spot. Results from this research may aid breeders, nursery producers, and landscapers in selecting crapemyrtle species and cultivars with cercospora leaf spot resistance.
Plant reserves play a key role in woody perennial plant winter survival and growth resumption in the spring. In fruit crops, reserves are critical for production in temperate climates when nutrient uptake is minimal and photosynthate production is limited in newly emerged leaves. Fall nitrogen (N) fertilization can be used to increase the availability of plant reserves to support and enhance vegetative growth and fruit production the following growing season. The objective of this study was to test the effect of fall N fertilization on fruit production by evaluating yield components and their relationships to vegetative growth. A split-plot design was established in three ‘HyRed’ cranberry production beds at a farm in central Wisconsin in a 3-year study. Fall N treatments were the main effect and consisted of plots receiving a single application of 0%, 10%, 20%, and 40% of the standard N application (67 kg⋅ha–1) used during the growing season. Summer N fertilization treatments were split in five weekly applications as subplots and consisted of a complete (100%) and a balance (60%, 80%, and 90%) of the standard N application (67 kg⋅ha–1) used during the growing season. Yield was unaffected by either the fall or summer fertilization treatments, but there was an increase in berry weight and a reduction in the number of fruit per unit area using the 40% fall N fertilization treatment. The lower number of fruit per unit area resulted from an increase in the proportion of vegetative uprights—a phenomenon related to an increased length of uprights. Prolonged growth may have affected the flower bud induction window, which occurs in early fall. The fall N fertilization effect of increased vegetative growth may have been the result of an increased availability of N in spring. This result could be advantageous in the establishment of new beds or the recovery of vines that have experienced stress.