Two studies were established in upland native forest of northwestern Kauai before Hurricane Iniki (Sept. 1992). One study was a gradient study in Acacia koa forest in the leeward rain shadow and the second study was a replicated fertilization experiment in mesic Metrosideros polymorpha forest. Both studies escaped devastation by high-intensity microbursts. Removal of LAI (from 3% to 80%) was proportional to pre-hurricane LAI, suggesting that resistance to damage was higher in low LAI, low-productivity sites. LAI recovered to prehurricane levels within 2 years, except in plots with major limb and stem loss. In the Acacia forest, damage to overstory trees was less than to understory trees, whereas in Metrosideros forest, larger trees were more damaged than smaller trees. During 2 years of recovery, both forests lost LAI in winter storms nearly equivalent to the hurricane damage. Disturbance is more frequent than previously known, which suggests that chronic disturbance needs to be better understood as a force regulating ecosystem structure and function. In both studies, the relative rate of recovery was faster in the more productive but more disturbed plots, suggesting that ecosystem resistance and resilience were traded off. These results have application to land use planning, agroforestry systems management, and other perennial crop management decisions following damage by a tropical cyclone.
The seeds of difficult-to-germinate native species of American licorice (Glycyrrhiza lepidota Pursh), angelica (Angelica atropurpurea L.), wild blueberry (Vaccinium angustifolium Ait.), wild mint (Mentha arvensis L.), and purple coneflower (Echinacea angustifolia D.C.), were soaked in 0, 2.5, 5.3, or 7.6 m KOH solutions for 0, 1, 5, 10, 15, or 20 minutes. After these treatments, germination was determined at 10 °C with a 14-hour photoperiod in petri dishes and seedling emergence was conducted at 14/10 °C with a 14-hour photoperiod in a sandy loam soil. In general, KOH treatment for only 1 min enhanced germination and seedling emergence. The optimal KOH concentration and soaking time in improving seed germination and seedling emergence varied with species, being 5.3 m and 10 min for purple coneflower, 5.3 m and 5 minutes for wild blueberry, 7.6 m and 5 minutes for angelica, 7.6 m and 1 minute for wild mint, and 5.3-7.6 m and 10 minutes for American licorice, respectively. Prolonged soaking, particularly in high concentrations, reduced germination and emergence.
Fatty acid is known as a physiologically active compound, and its composition in rice may affect human health in countries where rice is the major diet. The fatty acid composition in brown rice of 120 Korean native cultivars was determined by one-step extraction/methylation method and GC. The average composition of 9 detectable fatty acids in tested rice cultivars were as followings: myristic acid; 0.6%, palmitic acid; 21.2%, stearic acid; 1.8%, oleic acid; 36.5%, linoleic acid; 36.3%, linolenic acid; 1.7%, arachidic acid; 0.5%, behenic acid; 0.4%, and lignoceric acid; 0.9%. Major fatty acids were palmitic, oleic and linoleic acid, which composed around 94%. The rice cultivar with the highest linolenic acid was cv. Jonajo (2.1%), and cvs. Pochoenjangmebye and Sandudo showed the highest composition of palmitic (23.4%) and oleic acid (44.8%), respectively. Cultivar Pochuenjangmebye exhitibed the highest composition of saturated fatty acid (28.1%), while cvs. Sandudo and Modo showed the highest mono-unsaturated (44.8%) and poly-unsaturated (42.4%) fatty acid composition, respectively. The oleic acid showed negative correlation with palmitic and linoleic acid, while positive correlation between behenic and lignoceric acids was observed.
An in vitro shoot regeneration procedure was developed for native spearmint (Mentha spicata L.) using internodal explants. Shoot regeneration from internodes was evaluated on Murashige and Skoog (MS) media supplemented with individual cytokinins thidiazuron (TDZ), benzylaminopurine (BA), kinetin (KT), or zeatin (ZT) or various pair wise combinations of these. The highest regeneration was achieved by the second internode on a medium containing MS basal salts, B5 vitamins, 10% coconut water, 1.0 mg·L–1 TDZ, 2.5 mg·L–1 ZT, and solidified with 0.2% phytagel. Unlike previous protocols this medium does not need sub culturing and produces elongated shoots in 4 weeks, rather than 6 weeks. Maximum number of shoots (36 per explant after 4 weeks) was observed when internodes from 2-week-old stock plants were used as explant source. The shoots were removed and roots were initiated on medium containing MS basal salts, 0.4 mg·L–1 thiamine-HCL, 100 mg·L–1 myo-inositol, 7.5 g·L–1 agar and 0.01 mg·L–1 ∝-napthaleneacetic acid (NAA) and then plants were transferred to the greenhouse 2 weeks after root initiation, where 100% of the plantlets developed into healthy plants.
The Legislative Commission on Minnesota's Resources funded a two year research project to promote expansion of the native wildflower and grass seed industry in Minnesota. Production of seeds and plants for landscaping and restoration is a growing sector of the horticultural industry, yet documentation of production techniques is sketchy due in part to the large number of species. The species Lilium philadelphicum (wood lily), Phlox pilosa (prairie phlox), and Spartina pectinata (prairie cordgrass) were selected for further analysis of germination requirements. These species were noted by producers as having poor and/or unreliable germination. Cold moist stratification and gibberellic acid (GA) treatments were applied Total percent germination and mean days to germination were calculated and analyzed after 30 days under greenhouse growing conditions. Stratification improved total percent and mean days to germination in L. philadelphicum. P. pilosa responded to treatment by both stratification and GA. Four weeks of stratification may be the best method for decreasing mean days to germination while obtaining adequate total percent germination for S. pectinata.
Fifty nine morphological characters and isozyme band patterns of glutamate oxaloacetate transminase, peroxidase, glucose phosphate isomerase from fully expanded leaves were used for taxonomic study on 51 taxa consisted of Korean native and principal cultivars of the genus Pyrus. Taxonomic relationships were analyzed by complete cluster analysis method based on Euclidean taxonomic distance of IBM PC SPSS/PC+(ver. 3.0). Among the 39 qualitative morphological characters, a great deal of variations among 51 taxa were observed in immature fruit shape, skin lusterness, hair density on pedicel, anther color, shape of leaf apex and base, hair density on leaf surface, and leaf margin. Considerable variations were found in most tested quantitative characters except in the number of petals and styles. More reliable taxonomic results could be obtained by comparing morphological characters rather than examining isozyme band patterns. Even though there were considerable differences depending upon the methods of investigation, classification of the genus Pyrus by using isozyme band patterns was proved to be a good tool for rapid taxonomic studies.
Abstract
Seedlings from 21 collections of the native North American red raspberry, Rubus idaeus strigosus (Michx.), were screened for reaction to Amphorophora agathonica Hottes, the aphid vector of the red raspberry mosaic virus complex. Sixty-four seedlings from 1,041 screened were selected for resistance to colonization. Three of these were intercrossed and also crossed with 2 cultivars of R, i. vulgatus Arrhen origin to produce F1 progenies. Inheritance of the resistance reaction in the 3 selected seedlings appeared to be controlled by 2 dominant complementary genes. These genes, which are designated Ag2 Ag3, do not appear to give as high a level of resistance to the aphid as gene Ag1, which is of R. i. vulgatus origin and gives virtual immunity. It is suggested that genotypes combining Ag, with Ag2 and Ag3 might be of value in reducing genetic vulnerability if virulent biotypes of A. agathonica appear. Screening for reaction to the aphid under laboratory conditions, prior to field planting, eliminated large numbers of susceptible seedlings. Additional screening in the field the year of planting eliminated more. Segregation ratios, which had been adjusted from the field results, gave better agreements than laboratory screenings alone to the proposed hypotheses.
The oil of evening primrose (Oenothera sp.) is an important source of gammalinolenic acid (GLA). GLA [C18:3Δ6,9,12] is an unsaturated fatty acid in demand for its nutritional and pharmaceutical application. Oenothera biennis L. is the primary commercial source of evening primrose oil. A study was conducted to determine if species of Oenothera, adapted to Texas, produce GLA levels comparable to O. biennis. This project identified and evaluated the fatty acid composition of eight species of evening primrose native to Texas. GLA levels of 54 accessions evaluated from collected seed ranged from 0.0% to 11.0%. Field experiments were then conducted to determine oil content, fatty acid composition, seed yield, and potential adaptation to commercial production of selected accessions. Mean GLA levels of cultivated seed from these accessions ranged from 0.0% to 10.1%. Mean seed oil content ranged from 7.3% to 21.7%. Of the species examined, O. elata subsp. hirsutissima (A. Gray ex S. Watson) W. Dietrich and O. jamesii (Torrey & Gray) demonstrated GLA levels and seed yields adequate for commercial production. Based on these results, O. elata subsp. hirsutissima and O. jamesii demonstrated sufficiently high GLA levels, oil content, and seed yields to be considered for commercial production.
National demand for authentic Southern cuisine has contributed to the increased utilization of mayhaw fruit. Certain fruit characteristics are essential for the processing of mayhaw. Most of the mayhaw fruit used in processing comes from wild populations. Efforts are being made to identify superior clones from native populations. This study was undertaken to determine the chances of finding a superior clone with desirable processing attributes in a completely random population of mayhaw seedlings. Trees were removed from a 36 year-old mayhaw seedling orchard and relocated to a new orchard. The original orchard contained over 1500 trees. Five years after establishment in the new orchard, fruit were harvested from 75 of the trees and evaluated for fruit weight, percent malic acid, percent soluble solids, and color. Of the 75 trees, 48 were within one standard deviation of the mean trunk diameter. Seven trees fell below 12.1 cm and only 4 trees were larger than 19 cm. The mean fruit weight was 2.1 g with a range from 1.77-2.4 g. Sixty-seven percent of the trees produced fruit having weights within one standard deviation of the mean. Percent malic acid of mayhaw juice averaged 1.35% among the 75 trees. Seventy-two percent of the trees produced fruit with percent malic acid within one standard deviation of the mean. Mean percent soluble solids of mayhaw juice were 6.1 with a range of 5.36% to 7.01%. Seventy-three percent of the trees produced fruit with soluble solids percentages within one standard deviation of the mean. The probability of finding individuals in this population that exceeded the mean of these parameters (percent malic acid,%SS, and fruit weight) is less than 10%.
Native grass species, when used as low-input turf, offer many benefits that could address concerns about water use, sustainability, and increased turf management operating expenses ( Diesburg et al., 1997 ). Low-maintenance turf often has lower