Studies based on X-ray photographs were conducted to predict the morphology of tomato (Lycopersicon esculentum Mill.) seedlings at transplanting stage. Currently, seed-lot quality of tomato seeds for growing commercial transplants is determined with grow-out tests in the greenhouse because the standard germination test fails to predict the percentage of normal or usable transplants (UTs). These grow-out tests, however, are difficult to standardize. An X-ray evaluation procedure is presented as an alternative. X-ray images nondestructively provide information on embryo size and morphology and the amount of endosperm and the area of free space. These parameters correlate well with the morphology of 14-day old seedlings. Cotyledon morphology has the highest correlation with the percentage of UTs. A test based on the evaluation of X-ray images, classifying the cotyledon morphology and seed free space, predicts the percentage of UTs more accurately than the currently used germination test. A second method based on an equation that uses the probabilities of all X-ray categories proportionally predicts the percentage of UTs of primed seeds more accurately than the first method. Selecting individual seeds based on X-ray images has the potential to raise the percentage of UTs of seed lots. On the average, the percentage of UTs of control seeds was 22% higher after hand selection based on X-ray evaluation. Primed seeds gave 12% higher results. Hence, X-ray analysis can predict seedling performance and enable the selection of high-quality seeds.
dormancy induction regimes [S. Joyce and S. Kiiskila, British Columbia Ministry of Forests and Range (BCMOFR), personal communication, 2009]. Studies have compared the effects of a SD regime with a moderate moisture stress regime on seedling morphology and
Benzylaminopurine and chlorflurenol were applied to 2-1 nursery stock of Scots pine and ponderosa pine and 2-0 nursery stock Colorado blue spruce and Black Hills spruce to determine if crown morphology was influenced by varying combinations of the two plant growth regulators. Four levels of benzylaminopurine, 0, 250, 750 and 1250 ppm, and two chlorflurenol levels, 0 and 1% (v/v) were tested. Morphological response to treatments was significantly enhanced when treatments were applied to open, elongating buds. Benzylaminopurine significantly increased bud and shoot formation, while chlorflurenol significantly reduced height and increased branch length at species dependent concentrations. The two plant growth regulators lacked positive synergistic effects.
Benzylaminopurine and chlorflurenol were applied to 2-1 nursery stock of Scots pine and ponderosa pine and 2-0 nursery stock Colorado blue spruce and Black Hills spruce to determine if crown morphology was influenced by varying combinations of the two plant growth regulators. Four levels of benzylaminopurine, 0, 250, 750 and 1250 ppm, and two chlorflurenol levels, 0 and 1% (v/v) were tested. Morphological response to treatments was significantly enhanced when treatments were applied to open, elongating buds. Benzylaminopurine significantly increased bud and shoot formation, while chlorflurenol significantly reduced height and increased branch length at species dependent concentrations. The two plant growth regulators lacked positive synergistic effects.
120 COLLOQUIUM 3 (Abstr. 1000-1005) Seedling Morphological and Physiological Adaptation to Abiotic Stress
Breaking of dormancy in african juniper (Juniperus procera) seeds is a challenge faced by nurseries attempting to grow large numbers of this plant for restoration projects. The purpose of this study was to develop a protocol for breaking dormancy and stimulating germination in african juniper. Seeds were presoaked in different concentrations (0, 1, 10, or 20 mg·L−1) of gibberellic acid (GA3), indole-3-butyric acid (IBA), and naphthalene acetic acid (NAA), and incubated under different air temperatures (10, 15, and 20 °C). The petri dishes were monitored daily for 84 days, to record germination percentage, rate, and uniformity, and the growth of shoots and roots, and biomass production. The highest germination percentages were obtained under 20 °C with a high concentration of NAA (20 mg·L−1). The greatest seedling growth was under 20 °C with IBA. The greatest seedling length was under 20 °C with a low concentration of IBA (1 mg·L−1). The greatest shoot fresh weight was under 20 °C with medium GA3 concentration (1 mg·L−1). Compared with the control, almost all growth regulator treatments stimulated higher germination percentages and vigor indices with increased temperatures.
Light-emitting diodes (LEDs) are known to affect plant morphology. In this study, we examined the relationship between changes in stem and root morphology in Populus sieboldii × Populus grandidentata induced by irradiation with blue (450 nm), red (630 nm), and white (combination of red, blue, and green; 525 nm) LED lights. Populus samples were reared for 36–55 days in separate LED incubators, and changes in their appearance were observed. After rearing, the main stem of each seedling was cut, leaving a section of stem extending from the roots to ≈20 mm above the medium surface; this part was used for tensile testing. The tensile tests were performed to clarify the relationship between the tensile force and displacement until 100 mm. Irradiation with blue light produced the tallest seedlings. The highest dry weight (root and stem) and largest stem diameter were obtained under red light. The results of the tensile tests showed that the work required to displace seedlings 100 mm was highest in plants reared under red light, followed by white and blue light. Numerous root branches developed under red light, and taproots were longest in saplings reared under blue light. The observed differences in root system morphology that were induced by rearing under light of different wavelengths were reflected in the tensile force required to extract the trees from the medium. The morphological changes observed in roots are important given the role of roots in forests after landslides, earthquakes, and other disruptions.
120 COLLOQUIUM 3 (Abstr. 1000-1005) Seedling Morphological and Physiological Adaptation to Abiotic Stress