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  • Author or Editor: W. F. Campbell x
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Abstract

Carrot roots (Daucus carota L.) and onion bulbs (Allium cepa L.) were planted in Kidman silt loam immediately after DCPA (dimethyl tetrachloroterephthalate), ethofumesate (2-ethoxy-2,3-dmydro-3,3-dimethyl-5-benzofuranol methanesulfonate), linuron (3-(3,4-dichlo-rophyenyl)-l-methoxy-l-methylurea), napropamide (2-(a-naphthoxy)N,N-diethylpropiona-mide), or trifluralin (a,a,a-trifluoro-2,6 dinitro-N,N-dipropyl-p-toluidine) had been soil incorporated. In a second experiment, carrot roots and onion bulbs were planted in a conventionally-prepared seed bed or among vigorously growing wheat plants (7 to 10 cm tall). DCPA, linuron, and oryzalin (3,5-dinitro-N 4,N 4-dipropylsulfanilamide) plus glyphosate (N-(phos-phonomethyl)glycine) were surface applied to these seedbeds after planting but prior to crop emergence. Methazole (2-(3,4-dichlorophenyl)-4-methyl-l,2,4-oxadiazolidine-3,5-dione) and nitrofen (2,4-dichlorophenyl-p-nitrophenyl ether) were applied postemergence. Chemical treatments significantly altered the seed yields within the no-tillage method. Carrots grown in the tilled plots exhibited no effect of chemical treatments on seed yield. Comparison of tillage methods indicated a highly significant reduction in carrot seed yield relative to the no-tillage plots. Those on the non-weeded control and no-tillage plots showed a highly significant reduction in seed yield. Many of the onion bulbs from male-fertile lines failed to develop seedstalks in the plots sprayed with linuron and napropamide and those that did were delayed in development. Linuron and ethofumesate reduced the numbers of onion flowers per umbel. Onions grown in the tilled plots exhibited no effect of chemical treatments on seed yield. Those on the non-weeded control and no-tillage plots showed a highly significant reduction in onion seed yield. Comparison of tillage methods indicated a highly significant reduction in onion seed yield relative to the no-tillage plots.

Open Access
Authors: and

Evolution of hydrogen gas (H2) during N2 reduction in root nodules results in inefficient use of energy needed for N2 fixation. Cultivars of chickpea (Cicer arietinum L.) were inoculated with Rhizobium strains with and without genes for uptake hydrogenase (Hup) activity. H2 evolution, acetylene reduction activity, and uptake hydrogenase (Hup) activity were assayed on the resulting nodules. The Hup strains produced higher plant yields than the Hup+ strains. The +N controls produced significantly higher yields than the –N controls and plants inoculated with Rhizobium strains. Hydrogen uptake activity by Rhizobium strains was influenced by the cultivar characteristics. Expression of the plasmid-borne hup genes (pHU52) of Bradyrhizobium japonicum was modified by the host cultivar. The average nodule fresh weight and shoot and root dry weights of the cultivars significantly increased following inoculation with the transconjugant Hup+ Rhizobium strain. Thus, biological N2 fixation may be enhanced by selecting Rhizobium strains that are appropriately matched to the particular cultivar. Incorporation of transconjugant Hup+ genes can increase rhizobial activity.

Free access

Calcium maintains plasma membrane integrity, osmoregulation and extends the quality of shelf-life of sour cherry, Prunus cerasus L., fruit. Cherry fruit clusters were sprayed with Calcium Metalosate [an amino acid calcium chelate (AACa), Albion Labs, Inc., Clearfield, UT] solution. AACa-treated and untreated cherries were hand-harvested and placed in plastic bags. For comparison of Ca compounds, hand-harvested cherries were placed in cold tap water or 2% calcium chloride (CaCl2). All cherry samples were transported on ice to the lab, stored at 4°C for 24-48 h, and processed for membrane-enriched vesicle fractions. Membrane protein content was about 4-fold greater in Ca-treated fruit than in controls. 45Ca2+ uptake by the vesicles was ATP-dependent with the radiotracer accumulated by the vesicles being released when the calcium ionophore A23187 was added. ATPase activity and H+-pumping were both completely inhibited by orthovanadate, suggesting that the fractions were free from non-plasma membrane ATPases. Because CaCl2 is caustic and causes corrosion of equipment, our results suggest that spraying AACa may offer an alternative application of Ca.

Free access

Abstract

Inbred onions, Allium cepa L., were grown with different levels of fertilizer and soil moisture to determine treatment influence on seed yield. Nitrogen (253 kg/ha) alone or in combination with P (162 kg/ha) reduced plant survival, umbels per plant, pollination index, and seed yield where soil moisture was low but the reduction was nil or not as severe where soil moisture was high.

Open Access

Abstract

We investigated the areas of water penetration and the anatomical structures of hilar regions of permeable and impermeable seed coats of lima beans (Phaseolus lunatus L.). Results indicate that water can enter permeable seeds through the hilum, raphe, and micropyle. In impermeable seeds water cannot pass through any of these areas. Anatomical data confirm that there were no structural differences in the testae of permeable and impermeable seeds, but a noticeable difference was apparent in the hilar region. In permeable seeds the palisade layer did not connect evenly in the hilar canal. By contrast, the hilar canals of impermeable seeds had connected palisade layers that were uniformly coated with a cuticular layer. Micropylar openings were clearly visible in permeable seeds, but these openings were occluded and well covered with cuticle in impermeable seeds. Visible differences were evident in the raphe.

Open Access

Abstract

A path-coefficient analysis was used to furnish information on the inter-relationships of pollinating insect activity and components of seed yield in inbreds of Allium cepa L. The inbreds differed very significantly in their attractiveness to pollinating insects. Only one inbred exhibited a significant correlation (P <0.05 positive) between numbers of honey bees and seed yields. Separating the correlation coefficients into components of direct and indirect effects indicated that pollination attractiveness was not the limiting factor in seed set for inbreds in the experiment. Moreover, most of the variation in seed yield could be attributed to indirect effects on the components of yield, umbels per plant, flowers per umbel, percent per fertilized flower, and seeds per fertilized flower.

Open Access

Abstract

Abscisic acid (ABA) concentrations were significantly higher in young leaves of N-deficient (stressed) plants of tomato (Lycopersicon esculentum Mill.) both at day 2 and day 7 after transfer to a N-free Hoagland's solution. In old leaves, N-deficiency significantly increased ABA concentrations after 2 days but not after 7 days.

Open Access

An experiment was conducted to determine if gibberellic acid (GA; ProGibb, Abbott Labs) can be mixed with Aliette or Agri-Mek and oil to reduce application costs, without reducing GA efficacy, and if Silwet and Kinetic adjuvants enhance GA efficacy. Five tank mixes were tested along with a nonsprayed control. The tank mixes included: 1) GA, 2) GA + Silwet, 3) GA + Kinetic, 4) GA + Silwet + Aliette, and 5) GA + Silwet + Agri-Mek + oil. All compounds were applied at recommended concentrations. In September, ≈24 L of each tank mix was applied with a hand sprayer to mature `Hamlin' orange trees [Citrus sinensis (L.) Osb.] on sour orange (Citrus aurantium L.) rootstock. Peel puncture resistance (PPR), peel color, and juice yield (percent juice weight) were evaluated monthly between Dec. 1997 and Mar. 1998. On most sampling dates the fruit of treated trees had higher PPR and were less yellow in color than fruit from control trees. However, in Jan., fruit treated with GA + Silwet and GA + Kinetic had greater PPR than other treatments. In Feb., fruit treated with GA + Silwet + Agri-Mek + oil had the lowest PPR. The effect of the different tank mixes on juice yield was usually similar to the effect of the tank mixes on PPR and peel color. On 8 Jan. 1998, fruit from trees treated with GA alone yielded significantly more juice than fruit from control trees. On 24 Feb. 1998, fruit from trees treated with GA alone yielded more juice than fruit from the other treatments. Thus, GA efficacy is generally not reduced by these tank mixes, nor improved by adjuvants.

Free access

Gibberellic acid (GA) applied in late summer or fall delays subsequent loss of peel puncture resistance (PPR) and development of yellow peel color in many citrus cultivars. Our objective was to determine the optimal time to apply GA for increasing juice yield of `Hamlin' sweet orange [Citrus sinensis (L.) Osb.]. Mature trees on sour orange (Citrus aurantium L.) rootstock were sprayed with ≈24 L of a solution of GA (45 g a.i./ha) and organo-silicone surfactant (Silwet, 0.05%). Trees were sprayed on 26 Aug., 9 Sept., 2 Oct. (colorbreak), or 13 Oct. 1997, or nonsprayed (control). Peel puncture resistance, peel color, and juice yield were evaluated monthly between Dec. 1997 and Mar. 1998. Fruit from trees sprayed with GA had peels with higher PPR and less yellow color than fruit of control trees for most of the harvest season. The effect of GA on PPR and peel color lasted about 5 months. Juice yield was usually numerically greater for GA-treated fruit than for nontreated fruit. Fruit treated with GA at color break had significantly greater juice yield when harvested in late February than fruit from control trees. Thus, GA applied at color break appears to be the most effective time for enhancing peel quality and juice yield of `Hamlin' oranges.

Free access

Abstract

The discovery of cytoplasmic male sterility in onions, and its application to commercial seed production, was a major breakthrough in vegetable breeding. Initial use of this new technique was moderately successful and seedsmen assumed that experience would lead to higher seed yields. Instead, yields have been disappointing; many fields have not even been harvested. The resulting economic problem has become serious for both seedsmen and onion producers. Many suggestions have been made as to the cause of low yields but there is no agreement on the biological nature of the problem. Therefore, during the 1966 growing season we began to analyze the problem by following the development of the seed crops in commercial fields in southwestern Idaho. We believe our methods and preliminary data may be useful in stimulating other workers to also examine this problem.

Open Access