Seed-setting in potatoes as affected by spraying with a-naphthaleneacetamide and by light
SummarySpraying potato plants with dilute concentrations of a-naphthal-eneacetamide was not effective in increasing flower or seed ball production in the greenhouse at Beltsville Maryland, or Greeley, Colorado. Higher concentrations reduced flower production at Presque Isle, Maine.Sebago and Irish Cobbler produced more seed balls at Greeley than at Beltsville. Less cloudy weather at Greeley during the winter months is probably the chief factor responsible for this result.S 245–25, when self-pollinated, produced as many seed balls at Beltsville as at Greeley. It appears that this variety flowers and sets seed more readily under fairly unfavorable light conditions than either Sebago or Irish Cobbler.
Application of certain hormones to prevent flower abscission in two potato (Solanum tuberosum) varieties
SummaryInvestigations were undertaken to obtain flowers and fruit set in two potato varieties, namely, Canoga and Russet Burbank. Almost always in Russet Burbank, and quite often in Canoga, the flower buds drop. Seven hormones were used and a 25 p.p.m. aqueous solution of each was prepared. Potato plants were sprayed with hormones at different stages of plant development. These stages were; seed tuber stage, four-inch stage, fully grown plant stage, and flower bud stage.The results indicate that in the Canoga variety, flowers and fruit were obtained when the plants were sprayed with any of the above-mentioned hormones at any stage, but the fully-grown-plant stage proved to be better for hormone treatment since it affects flower development. At this stage the best flowering and fruit set were obtained by the application of 2,4-D followed by IBA, 2,4,5-TCPA, and 2,4,5-TCPP.In the case of Russet Burbank more selectivity as to stage of plant growth and type of hormone was required to obtain good flowering and fruit set. The four-inch stage proved to be better and at this stage the application of NAA and 2,4,5-TCPP gave the best results with IBA as third choice.These results were obtained from a single experiment. In order to make definite recommendations much more research will have to be conducted.
Effect of Soybean Cyst Nematode (Heterodera glycines) on Yield of Resistant and Susceptible Soybean Cultivars Grown in Ohio.
Soybean (Glycine max) producers in Ohio rarely use soybean cyst nematode (Heterodera glycines, SCN)-resistant cultivars because of concerns over limited yield potential and lack of resistance to Phytophthora sojae. A two-year study was initiated to determine grain yield and nematode population increase on soybean cyst nematode-resistant cultivars in maturity groups II and III in production fields. Sites differed in soil texture, nematode densities, and P. sojae infestation at a number of locations in Ohio. Soil was assayed for nematode densities before planting and at harvest. Yields of resistant cultivars averaged 0% to 18% higher than those of susceptible cultivars in fine-textured soils with average preplant populations ranging from 463 to 14,330 SCN eggs/100 cm(3) soil. In coarse-textured soils, yields of susceptible cultivars were 21% to 56% less than the resistant cultivars with average preplant densities ranging from 1,661 to 15,558 SCN eggs/100 cm(3) soil. The reproductive index ranged from 0.1 to 5.5 for resistant cultivars and 0.4 to 112 for susceptible cultivars. In 1993, yield of P. sojae-susceptible, nematode-resistant 'Asgrow A 3431' was as high as yield of the P. sojae-resistant, nematode-susceptible cultivar 'Resnik' in a Phytophthora-infested field. The nematode-resistant cultivars Madison Experimental 131527 and Asgrow A3431 had higher yields than AgVenture AV1341 and susceptible cultivars Resnik and Kenwood when compared over five nematode-infested sites. Nematode-resistant cultivars were found to be excellent alternatives to currently grown susceptible cultivars for managing SCN where group III cultivars are used. However, better cultivar alternatives may be needed for sites with combined Phytophthora root rot and cyst nematode problems.