Search Results

You are looking at 1 - 10 of 14 items for

  • Author or Editor: F. G. Martin x
Clear All Modify Search

Abstract

Strawberries (Fragaria × ananassa Dutch.) were grown during 2 seasons to evaluate 5 N sources and 2 times of N and K application using trickle irrigation with N and K rates of 134 and 149 kg ha−1, respectively. Fruit yields were influenced by significant interactions between N-source and time of N and K application during both seasons. With 100% of the N and K applied preplant, marketable fruit number and weight were significantly greater with sulfur coated urea (SCU) or isobutylidene diurea (IBDU) than with urea, NH4NO3 or KNO3 + Ca(NO3)2 as the N sources. With 40% of the N from the above 5 sources applied preplant and 60% of the N and K supplied with the trickle irrigation from NH4NO3 + K2SO4 or KNO3 + Ca(NO3)2, production was similar with all N sources. Leaf tissue N and K concentrations were not influenced consistently by N source. During both seasons, leaf N concentrations were higher with the split than with the 100% preplant treatments.

Open Access

Abstract

Plant growth and fruit yield were enhanced by broadcast as compared with band applications of either N-P-K fertilizer or micronutrients. Plant dry wt were similar with applications of either CuSO4-5H2O at 4 and 8 lb./acre Cu or complete micronutrient frit (FTE 503) at 30 and 60 lb./acre in 2 seasons. In 1 season, fruit yields were significantly higher where CUSO4 was used. Increases in rate of either micronutrient source resulted in increased fruit yields where applications were broadcast but a decrease where banded. These responses to increased micronutrient rates were related to an increase in micronutrient efficiency with the broadcast placement and to a toxicity with the band placement.

Open Access

Abstract

Seeds of ‘Florida-Sweet’, a high-quality, fresh market, sh2 sweet corn (Zea mays L.), tend to have low germination and the seedlings are also more susceptible to root rot than standard sweet corn (su). Difolatan plus benomyl as seed protectants controlled the soil fungus complex and significantly improved yields without reducing ear quality. Compensated-rate seeding, or seeding adjusted according to germination percentage to give 54,000 plants/ha with seeds of 70% to 100% germination, produced no yield or quality reduction in most cases. However, regression analysis showed in 1 out of 3 tests a significant linear decrease between seed germination percentages and yields of U.S. Fancy ears.

Open Access

Abstract

Dikegulac [2,3:4,6-bis-0-(1-methylethylidene)-a-L-xylo-2-hexulofuranosonic acid] was applied by handgun to the drip-point on May 27, 1978 at 0, 500, 1000, 1500, and 2000 ppm to trees of peach [Prunus persica (L.) Batsch cv. June Gold] 2 months after transplanting. Tree height and width decreased and lateral branching increased with increasing concentration of dikegulac. Phytotoxicity was concentration-dependent. All treatments were repeated on May 21, 1979, and a 3rd application of 500 and 1000 ppm was made on August 8, 1979. The best control of vegetative growth in 1979 was from biannual applications since foliar phytotoxicity was reduced. No effect on flowering date or number was detected in March 1980.

Open Access

Abstract

Absorption of 5-chloro-3-methyl-4-nitro-lH-pyrazole (Release) by ‘Valencia’ fruit (Citrus sinensis (L.) Osb) was determined at 6 different times of the year under 8 temperature and humidity regimes. Significantly greater absorption occurred with immature than with mature fruit. In general, adjuvants did not increase uptake over an aqueous control. The 3-way combination of Release plus Sweep plus 1 ppm cycloheximide (CYH) in April and May significantly increased uptake as did Release plus a formation of chlorothalonil (Sweep) on regreened fruit in July. One ppm CYH caused sufficient tissue damage to stimulate active uptake whereas 20ppm is toxic and inhibits uptake and/or symplastic retention. Best absorption for April and May, the usual harvest period, was obtained at 33°C and 50 to 65% relative humidity. Mature, regreened oranges in July had higher 14C-Release absorption than fruit from the same trees tested in April.

Open Access

Abstract

Strawberry (Fragaria × ananassa Dutch.) response to trickle irrigation was compared with overhead and no irrigation. Fertilizer rates were 94-55-104 to 202-118-223 kg/ha N-P-K with 0, 50, and 100% of the N and K applied with trickle irrigation. The remaining fertilizer for trickle and all for overhead and non-irrigated treatments was applied preplant. Fruit yields were increased 34% with overhead irrigation and 37% with trickle irrigation above that for non-irrigated treatments. With 0 and 50% of the N and K applied in daily or weekly increments with trickle irrigation, fruit yields were 2 and 20% greater than with overhead irrigation, 30 and 58% greater than with no irrigation, respectively. The N levels of leaf tissue samples were not influenced by treatment. Leaf K levels were significantly higher with trickle irrigation than with overhead irrigation or check treatments. Soil value for total soluble salts, K and NO3 were significantly lower with trickle irrigation than with overhead or no irrigation treatments.

Open Access

Abstract

Maintenance of adequate available soil N for bell pepper (Capsicium annuum L.) growth is essential to high production in Florida and requires mulching, fertilizer placement, and timing of fertilizer application. Slow-release N was supplied as sulfur-coated urea, isobutylidene diurea (1BDU), or ureaformaldehyde and was compared at 3 N rates with soluble sources such as urea, ammonium nitrate, and ammonium sulfate on ‘Yolo Wonder’ pepper. In the first season, highest yields and N concentrations of tissue occurred where IBDU and urea were applied broadcast with mulch as compared with band placement. In the second season, broadcast fertilizer placement with mulch was compared with 3 split-fertilizer applications without mulch. Fruit yield was affected by a significant interaction among N sources, N rates, and mulch. Highest fruit yields were obtained with SCU and IBDU applied under mulch at 224 kg N/ha. Leaf N was higher during the season with slow-release N than with soluble N. Soil analyses data from samples taken throughout the season showed that N source and rate significantly influenced the soil available N measured as urea-N, NH4-N, and NO3-N.

Open Access

Abstract

Concentrations of abscisic acid (ABA), dihydrophaseic acid (DPA), and their metabolites were measured in mature pear seeds, using gas-liquid chromatography (GLC). ABA content of Pyrus communis L. cv. Bartlett seeds fell during imbibition, but was not affected by temperature (4 vs. 21°C) or time (0 to 4 weeks) of stratification in a moist medium. Levels of DPA and 3 of its metabolites were not correlated with dormancy. The amount of chilling required to break dormancy was not correlated with ABA or DPA content in imbibed, non-stratified seeds of 6 Pyrus species.

Open Access

Abstract

Seeds from ‘Bartlett’ and ‘Winter Nelis’ and ovules from seedless ‘Bartlett’ pears were collected periodically between 25 days after full bloom and harvest. Extracts were analyzed for hormones by combined gas chromatography-mass spectrometry, using the technique of selected ion current monitoring. Levels of 6 gibberellins were low in all samples prior to appreciable embryo growth (25 days after full bloom). Content of gibberellins A17, A25, A45 and a presumed 3β-hydroxy gibberellin A45 rose dramatically during rapid embryo growth between 65 and 85 days after full bloom, while the gibberellin content of embryoless ovules of ‘Bartlett’ did not change during this period. Two unidentified gibberellin-like compounds, one isomeric with gibberellin A25 and the other corresponding to a hydroxy gibberellin A45, were detected 85 days after full bloom. Abscisic acid content was also maximal between 65 and 106 days, ovules of seedless ‘Bartlett’ exhibiting considerably higher concentration than seeds of either cultivar. Levels of 5 abscisic acid metabolites varied with seed type and sampling period. Phaseic acid levels remained low in ‘Bartlett’ seeds and ovules during all developmental stages but increased in ‘Winter Nelis’ seeds at 122 days. Concentration of cis, Trans-dihydrophaseic acid, although low, rose as ‘Winter Nelis’ seeds matured while ovules of seedless ‘Bartlett’ showed no such increase. Levels of 2 metabolites, tentatively identified as trans, trans-dihydrophaseic acid and a hydroxylated derivative of dihydrophaseic acid, varied only slightly with development. A third metabolite, characterized as a keto derivative of dihydrophaseic acid or a hydroxy-derivative of phaseic acid, was present in large quantities in unfertilized ovules during the early period of fruit growth, but increased in seeds only after 65 days. The possible roles of these compounds are discussed in relation to seed, fruit, and flower development.

Open Access

Abstract

‘Christian Dior’ and ‘Happiness’ roses on Rosa fortuniana stock, fertilized with 3 rates each of N, P, and K factorially combined, were grown for 3 years at Ft. Pierce, Florida. All fertilizer was applied at the beginning of the experiment under plastic mulch just before the bushes were planted. About 2300 lb./A of N on ‘Christian Dior’ and 2100 lb. on ‘Happiness’ produced the greatest number of flowers. Leaf N at 18 months was also maximized by 2100 lb. N. Nitrogen levels maximizing stem lengths were slightly lower. The independent effects of P were minor and low levels best, perhaps because residual soil P at start of the study was adequate. Flower production decreased with K fertilization beyond low rates, whereas stem lengths increased to a max at about 1700 lb./A. At times, various nutrient interactions were noted. ‘Christian Dior’ consistently yielded more flowers than ‘Happiness’. With minor exceptions, ‘Happiness’ had longer stems.

Open Access