Celery (Apium graveolens L.) seeds germinated at 10°C for 14 days produced shorter and more uniform radicles (0– mm) than seeds germinated for 8 days at 24° (0–10 mm). Removal of seed leachates improved the germination of celery seeds in the light. Celery seeds germinated at 10° prior to sowing emerged faster, and produced more uniform plants than those not pregermihated, and were not thermodormant when incubated at 32°.
A strain of the biocontrol fungus Trichoderma harzianum was tested for effectiveness in improving the performance of sh2 sweet corn using a variety of delivery methods. In greenhouse trials, Trichoderma seed treatment reduced the proportion of weak plants (unlikely to make a marketable ear) from 40% to 10%. This is evidence that the characteristically uneven stand establishment of supersweet corn should be overcome by using Trichoderma. In field trials, Trichoderma and Gliocladium (a related fungus) were inoculated as a seed treatment without fungicide in spring-tilled plots. Yields of uninoculated controls were 2.2, Gliocladium-treated were 2.6, and Trichoderma -treated were 3.6 T/ac. Delivering the same lines of fungus in the fall to a rye cover crop resulted in high populations the following spring. The cover crop was killed and fungicide-treated seed of `Zenith' sweet corn was planted without tillage. Yield with Trichoderma was 4.0, with Gliocladium was 3.7, and uninoculated was 2.4 T/at. The uninoculated, conventionally-tilled plots also yielded 4 T/at. Thus the beneficial fungi overcame the inhibition caused by no-till. Trichoderma was delivered effectively both as a seed treatment and on a winter cover crop to improve stand uniformity and overall yield.
A field experiment was conducted to quantify the ontogenetic changes in Ca concentration and content of pickling cucumber fruits as influenced by environmental conditions and genotype. Pericarp tissue Ca concentrations (1.1% to 0.7% of dry weight) were higher but declined less rapidly during fruit development than endocarp concentrations (0.8% to 0.2% of dry weight). About 90% of net fruit Ca content accumulated within the pericarp of ≈150 g fresh weight fruit, the rest in the endocarp. The rate of Ca accumulation was highly variable during fruit ontogeny but was closely correlated with growth rate (grams fresh weight/day). Environmental conditions had the largest effect on Ca accumulation rate. Fruit tissue Ca concentrations were affected both by genotype and the cultural environment, especially at the later stages of fruit development. Calcium concentrations (1.5 to ≈3.0% of dry weight) in fully expanded leaf tissue were higher than in rapidly growing fruit tissues on the same plants.
Pepper transplants (Capsicum annuum L.) held under simulated transit conditions synthesized substantial amounts of ethylene, the rate of which was temperature dependent. Transplants treated with known concentrations of ethylene (0, 0.1 to 10.0 μ1/liter) were substantially defoliated at levels lower than those that may be produced in transit by the plants themselves. Exposure to ethylene concentrations of 0.5 jul/liter and greater impeded the growth of transplants after planting into the field. Removal of ethylene in storage with potassium permanganate greatly reduced abscission. Elevated storage CO2 levels stimulated ethylene synthesis by as much as 34%.
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