Search Results
Abstract
Levels of auxin- and gibberellin (GA)-like substances were analyzed in floral buds, open flowers, and developing fruit of tomatoes (Lycopersicon esculentum Mill) subjected to 38°C for 5 hr. The levels of these substances were lowest at anthesis. The levels of GA-like substances in all analyses were lower than those of auxin-like substances. High temperature treatment decreased the levels of both substances, especially in floral buds and developing fruit.
Abstract
The in vitro flowering responses in conditions of total darkness were studied in several cultivars of diploid and tetraploid Brassica species. Diploid species with the A genome tended to form flowers about equally at high or low temperature, the single B genome species formed some flowers only at high temperature and those with C genome not at all. Similarly, allotetraploid species with the AC genomes tended to flower as did certain of those with the BC and AB genomes but to a considerably lesser extent. Leaf formation was correlated with flowering.
Abstract
One-month-old seedlings of 20 entries of tomato (Lycopersicon esculentum Mill.) were subjected to flooding for 3 days, or drenched with ethanol or (2-chloroethyl)phosphonic acid (ethephon) solution. Flooding reduced stem growth and leaf chlorophyll content of thelower leaves and promoted epinastic curvature of leaf petiole and adventitious roots. Application of ethephon elicited a response similar to that of flooding. No prominent morphological and physiological changes were observed from ethanol application. Flooded plants show increases in their endogenous free proline pool, which can be reduced by the withdrawal of flooding. Flooded L-123 plants, the most tolerant entry, accumulated the least free proline among three entries tested. Proline level appeared to indicate the intensity of oxygen deficiency during soil flooding by reflecting oxygen supply, and could serve as in indicator in relating plant injury to flooded conditions. The tolerance of L-123 to soil flooding, at least in part, depends on its ability to transport oxygen from the aerial part to the root.
Abstract
Axillary buds of heading Chinese cabbage (Brassica campestris L. Pekinensis group) cultured on a modified Murashige-Skoog medium containing 0.1 mg/liter 6-benzylamino purine and 1 mg/liter naphthalene acetic acid produced roots within 2 weeks. Plantlets grew into true-to-source plants when transplanted to soil in the greenhouse.
Abstract
Seed yield of Chinese cabbage (Brassica campestris ssp. pekinensis Rupr.) was studied at 34–37/22–24°C (day/night) temperatures applied at different growth stages. High temperatures at first anthesis and immediately after pollination diminished seed yield mainly through reduction in seed number. Hand pollination with pollen grains from plants reared under normal temperature improved seed yield of the plant heated at first anthesis. Both male and female gametogeneses appeared to be affected by high temperature based on seed set, but the most drastic effect of high temperature on seed yield occurred after pollination. In vitro pollen viability tests indicated that the optimum temperature for pollen grain germination and pollen tube growth was 20°. Temperatures below 16° or above 28° reduced pollen grain germination and pollen tube growth mainly because of an increase in burst pollen grains.
Abstract
The proline contents of anthers, pollen, pistils, and leaves were examined in several tomato (Lycopersicon esculentum Mill.) cultivars under different temperature conditions. The proline content in anthers increased with advancing development of floral buds to a maximum at anthesis. The pistil contained less proline than the anthers and did not accumulate proline with advancement of floral bud development in most cultivars. High temperature reduced proline content in anthers regardless of the stages of floral bud development. It also tended to reduce proline content in pistils of later floral bud stage. The proline content of the leaves was lower than that of anthers or pistils; however, high temperature increased the proline level in the leaves. Pollen collected from the hot-season planting contained less proline than that collected from the cool-season planting. The addition of proline to germination medium enhanced pollen germination rate and increased pollen resistance to heat. These results suggest that the low proline accumulation in anthers and pollen at high temperature may be the result of the high accumulation in the leaves. Also, high proline content in anthers may be necessary to confer heat resistance to pollen germinating at high temperatures.
Abstract
The distribution of 14C-photosynthates was examined in pot-grown Tainan-1 mung bean plants (Vigna radiata (L.) Wilczek var. radiata). Whole plants were assimilated with 14CO2 at anthesis, and at 7 and 17 days after anthesis. The 14C-photosynthate fixed at anthesis was retained mostly in the vegetative tissue. However, of the 14C-photosynthate fixed at early pod development stage (i.e. 7 days after anthesis), 15-26% of the assimilated 14C was detected in the reproductive tissue within 24 hours after exposure, whereas about 43% was detected at maturity (i.e. 38 days after anthesis). When plants with full grown pods (i.e. 17 days after anthesis) were treated, 70% of the 14C was detected in the reproductive tissue 24 hours after exposure and at maturity.
Abstract
High temperature tended to aggravate injury caused to tomato plants by flooding. Based on plant responses such as chlorosis, epinasty, and wilting, less than 0.2% (8 of 4630 accessions) of the world collection of the garden tomato (Lycopersicon esculentum Mill.) and related Lycopersicon species exhibited some level of tolerance to a short period of flooding associated with high temperature. The level of flood tolerance in one of the 8 flood tolerant accessions, L-123, was found to be less than that of 7 other vegetables tested.