Search Results
Abstract
Tandem mass selection in a sweet com (Zea mays L.) composite produced a 5-day gain in maturity, increased the percentage of plants with light-colored silks, and increased the number of kernel rows per ear. Although the differences in earworm resistance between generations were not statistically significant, they suggest a slight but steady increase through the first four cycles of selection. Because infestation of earworm [Heliothis zea (Boddie)] was very low in 1972, no selection was applied to the fifth generation for resistance, and the level of resistance based on mean larval weights and larval instars dropped. Tandem mass selection improved the sweet com population for certain agronomic characters, and maintained its level of earworm resistance.
Abstract
Mature green ‘Homestead’ tomatoes (Lycoperiscon esculentum Mill.) and 3 advanced breeding lines were treated with ethylene gas and some compositional parameters of the treated fruit were compared with those of control fruit. Tomato breeding line T3702j 2 showed a greater response to ethylene treatment than ‘Homestead’ and other advanced breeding lines carrying the crimson (og c) and high pigment-crimson (hp og c) genotypes. Ethylene treatment had negligible effects on the levels of soluble solids, dry matter, ascorbic acid, β-carotene, and lycopene in the genotypes studied. The mean pH of the treated samples was slightly higher than that of the control, but was not statistically significant in all cultivars or breeding lines every year. The data suggest that breeders should pay attention to the response of breeding lines and potential cultivars to ethylene-induced ripening.
Growth chamber studies were conducted to determine if inverse day/night temperature could control canopy height of sweetpotato without adversely affecting storage root yield. Four 15-cm-long vine cuttings of TU-82-155 sweetpotato were grown in rectangular nutrient film technique hydroponic troughs for 120 days. Two troughs were placed into each of six reach-in growth chambers and subjected to 24/18, 26/20, 28/22, 18/24, 20/26, and 22/28 °C, respectively. Growth chamber conditions included a 12/12-h photoperiod, 70% RH, and photosynthetic photon flux of 1000 μmol·m-2·s-1 at canopy level. Total and edible storage root yields were reduced by 50% among plants grown under cool days/warm nights regimes. Harvest index was similar among treatments except for the low value obtained at 22/28 °C. Canopy height was positively correlated with the change in temperature, and for every 2 °C decrease there was a 3.1 centimeter decrease in canopy height. Inverse day/night temperature effectively controlled canopy height but at the expense of storage root production.
Abstract
Four-node vine cuttings of yam (Dioscorea alata L.) treated with Rootone-F showed higher survival, higher growth rate, and 3 times the number of shoots per plant than 1-node untreated vine cuttings. Survival of rooted tuber sprouts was lower for 5 cm lengths than 12.5 or 20 cm lengths. Rooted tuber sprouts 12.5 cm long initiated more tubers and primary fibrous roots than 4-note vine cuttings treated with rooting hormone.
Abstract
Vine production from proximal and middle tuber sections of yam (Dioscorea alata L.), subdivided into whole, half and quarter pieces increased with tuber size. Vines produced from proximal, middle and distal tuber sections decreased significantly with distance from the proximal end. Smaller pieces collectively resulted in greater total vine length.
Abstract
Carbohydrate analyses were made at harvest and after 7 days of postharvest storage at 65°F on sweet corn hybrid cultivars with endosperm mutant genotypes ae wx, ae du wx, and sh 2 and of standard sweet corn (su 1). Cultivars with the mutant genotypes contained from 1.5 to 2.0 times as much total sugar at harvest as the standard. They also lost more total sugar during the post-harvest period. Still, the hybrids with ae du wx and sh 2 genotypes contained significantly more sugars than the standard after the 7-day storage treatment. The mutant cultivars were low in water soluble polysaccharides but relatively high in starch. All cultivars had approximately the same amount of total carbohydrate. Moisture loss from the kernels during the storage period was significantly less in the mutant cultivars. Therefore, they maintained their fresh appearance longer, and they were slower than standard sweet corn to show kernel denting. Taste tests indicated a preference for the sweetness of the ae wx and ae du wx genotypes over the standard cultivars Golden Security and ‘Iobelle’ (Florida 104), but they were rated below the standards for pericarp toughness. These studies indicated that, with further refinement of certain horticultural and quality characteristics, the ae wx, ae du wx, and sh 2 endosperm mutant genotypes have a definite potential for improving the initial quality and the ability for maintaining good quality during normal post-harvest handling of fresh sweet corn.
Abstract
Harvesting mature-green tomatoesis common practice where they are grown commercially for the fresh market. Usually, the tomato fields are picked 4 to 6 times in a season, as the most mature fruits on the vine reach the mature-green stage. If mechanical harvesting becomes a reality for fresh market tomatoes, a once-over harvest will probably be used instead of the usual multiple pick. Yields will then be limited by the number of fruits mature enough at a given time to ripen off-vine and meet market standards for color. It will be imperative to grow a variety that has a concentrated set and whose fruits have good ripening ability when harvested prematurely.
The effect of inoculation with Azospirillum brasilense strain Cd on mineral concentration in sweetpotato, [Ipomeo batatas (L) Lam cv. TI-155] tissue and ionic composition of plant nutrient solution was investigated in a greenhouse study. In the field, inoculation of sweetpotato with Azospirillum spp. has been reported to enhance. sweetpotato yield. In this study, 48-h old broth cultures were used as inoculum at a population density of approx. 1 × 108 cfu/ml. The inoculum (0.20 L) was added to the reservoirs containing 30.4 L of a modified half Hoagland's plant nutrient solution at 28 days after the start of the experiment Results indicate that percent total nitrogen in sweetpotato foliage tended to be higher for the inoculated fibrous mat than in the fibrous mat for non-inoculated plants. The percent total nitrogen in storage roots for the non-inoculated treatment tended to be higher than in storage roots for inoculated plants. Inoculation resulted in a slight increase in foliar phosphorus concentration but had no effect on phosphorus concentration in sweetpotato storage and fibrous root samples. Inoculation tended to reduce foliar calcium concentration. Magnesium concentration in leaf tissue was not influenced by inoculation. Foliar potassium concentration tended to increase slightly. The effect of inoculation on potassium concentration in sweetpotato root tissue was not well-defined; potassium concentration tended to be higher in fibrous root tissue for the inoculated treatment. But in storage root tissue, potassium concentration was higher for the non-inoculated treatment than for the inoculated treatment. Inoculation did not affect foliar concentrations of any of the micronutrients measured. This study indicates no effect of inoculation on ionic strength of nutrients in solution reservoirs.
Growth chamber studies were conducted to evaluate the effect of four diurnal temperatures (24/18C, 26/20C, 28/22C, and 30/24C) on yield, leaf expansion and unfolding, and vine length of sweetpotatoes [Ipomoea batatas (L.) Lam]. Four vine cuttings (15 cm in length) of `TI-155' and `Georgia Jet' were grown for 120 days using a modified half-Hoagland nutrient solution with a 1:2.4 N:K ratio. Irradiance at canopy level averaged 600 μmol·m–2·s–1 at an 18/6 photoperiod, and RH of 70%. Storage root number/plant for both cultivars decreased with increased temperature. Storage root fresh and dry weights for both cultivars increased with temperatures up to 28/22C and declined at 30/24C. Foliage fresh and dry weights were not influenced by temperature for either cultivar. Leaf expansion rate and vine length were highest at 26/20C and lowest at 24/18C for both cultivars. Leaf unfolding rate was not affected by temperature foe either cultivar, but was more influenced by time of measurements.
Growth chamber experiments were conducted to study the physiological and growth response of peanut (Arachis hypogaea L.) to 50% and 85% relative humidity (RH). The objective was to determine the effects of RH on pod and seed yield, harvest index, and flowering of peanut grown by the nutrient film technique (NFT). `Georgia Red' peanut plants (14 days old) were planted into growth channels (0.15 × 0.15 × 1.2 m). Plants were spaced 25 cm apart with 15 cm between channels. A modified half-Hoagland solution with an additional 2 mm Ca was used. Solution pH was maintained between 6.4 and 6.7, and electrical conductivity (EC) ranged between 1100 and 1200 μS·cm–1. Temperature regimes of 28/22 °C were maintained during the light/dark periods (12 hours each) with photosynthetic photon flux (PPF) at canopy level of 500 μmol·m–2·s–1. Foliage and pod fresh and dry weights, total seed yield, harvest index (HI), and seed maturity were greater at high than at low RH. Plants grown at 85% RH had greater total and individual leaflet area and stomatal conductance, flowered 3 days earlier and had a greater number of flowers reaching anthesis. Gynophores grew more rapidly at 85% than at 50% RH.