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  • Author or Editor: H. J. Mack x
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Abstract

Yields of snap bean pods were increased by irrigation and plant density in 4 field experiments. Highest yields were obtained with the −0.6 bar soil water potential regime which represented removal of 40-45 percent of the available soil water at 30 cm depth. Yields were lowest with the −2.5 bars soil water potential which represented 65-70 percent water removal. An average of 60 percent more water applied to the −0.6 bar than the −2.5 bars treatment increased yields approximately 54 percent. Yields were usually intermediate with the −1.0 bar soil water potential representing 50-55 percent available soil water removal. Two cultivars were used in 2 of the experiments and responded differently to irrigation. Yield of ‘Oregon 1604’ was higher than that of ‘Galamor’ with −0.6 bar soil water potential but was lower than ‘Galamor’ with −2.5 bars. Yield of ‘Oregon 1604’ averaged 27 percent higher in square arrangement than in 91 cm rows and the increase was greater for the high than for the low population density when compared in 1 experiment. Yield was 20 percent higher for high density of 43.0 plants/m2 than for low density of 21.5 plants/m2. Yields of 2 cultivars in 2 experiments averaged 67 percent higher in high density (40-57 plants/m2) than in low density (20-33 plants/m2) plantings. There were no consistent irrigation × density interactions. Usually there was a more rapid depletion of soil water for high density than for low density. Fiber in canned sieve size 5 pods was higher in ‘Oregon 1604’ at −2.5 bars soil water potential than for ‘Galamor’, but at the −0.6 bar soil water potential regime, the amount of fiber was similar in the 2 cultivars. Percent of pod weight attributed to seed and percent fiber were usually highest at −2.5 soil water potential.

Open Access

Abstract

Wider spacing and fertilizer application increased the weight of both axillary heads (AH) and main heads in an open-pollinated cultivar and an inbred line. AH weight increased more than main head weight. The effect of spacing on AH was greater than that of fertilizer application. Transplanting greatly decreased the development of axillary heads when compared with direct-seeding.

Open Access

Abstract

Incidence of head smut caused by Sphacelotheca reiliana (Kuhn) Clinton in sweet corn (Zea mays L.) was decreased by frequent early irrigation (total of 15-20 cm of water during the first 18 to 21 days after planting), compared to no irrigation during the same period. The percentage of infection increased as planting depth increased from 2.5 cm to 7.6 cm. Large seed produced fewer infected plants than small seed, whereas the percentage of infected plants produced from medium-size seed was intermediate.

Open Access

Abstract

Globe artichokes (Cynara scolymus L.) were grown from seed in the greenhouse and transplanted to the field in 1978, 1979, and 1980. Percentage of flowering without artificial vernalization of the transplants was 75%, 92%, and 99% for the 3 years. Nitrogen sidedress applications above a base rate of 48 kg N/ha did not significantly increase weight or number of buds per plant or buds/ha. Plant spacing of 1 × 0.6 m generally increased total weight and number of buds/ha, but reduced number and weight of buds/plant compared to spacings of l × lmorl × 2m. Average weight/bud was unaffected by either nitrogen level or plant spacing. Total yield was similar to California production of clonally produced artichokes, but buds were smaller.

Open Access

Abstract

The yield-plant density relationships of 5 bush snap bean cultivars and the effect of rate of N application on the yield-density relationship of a single cultivar were studied in 2 separate experiments. Responses were described by the equation W-θ = α + βρ where W is the pod weight per plant, ρ is the plant population density, and θ, α and β are constants. The θ, α and β values were tested for significant differences among the cultivars and levels of N. In experiment 1, θ = 0.836 was acceptable for all 5 cultivars and in experiment 2, θ = 0.897 was acceptable for the 3 rates of N. Values of θ were similar to those found for bush snap beans by other researchers. Significant differences existed among both α and β values of the cultivars. In the N experiment, α was constant but values of β differed significantly and were inversely related to the level of N. Optimum plant density was dependent on the cultivar and increased with the level of N.

Open Access

Abstract

‘Jubilee’ sweet corn (Zea mays L.) was grown under conventional tillage, strip tillage, and no-till methods in 1983 with 5 irrigation levels imposed on each tillage treatment. The crop-water production functions for evapotranspiration vs. yield were different in scale but similar in slope for the 3 tillage treatments. At each level of seasonal applied water, the conventional tillage produced significantly higher yields of husked sweet corn than did strip tillage, and strip tillage yields were significantly higher than those of no-till.

Open Access

Abstract

Leaves at nodes 4 or 8 of greenhouse grown beans, Phaseolus vulgaris L., cv. Puelba 152, were briefly exposed to 14CO2 at 35, 48, 63, or 70 days after planting. Prior to flowering, over 85% of the recovered 14C-activity translocated in 24 hours from node 4 was in roots, nodules, and lower stem. At flowering, radioactivity translocated to the lower stem decreased but correspondingly increased in nodules. Roots sequestered 45% of translocated-14C throughout the life of the node-4 leaf. About 80% of the 14C-activity exported from node 8 at flowering was in middle and upper stem sections, but during pod-fill over 85% moved into the pods and less than 1% to the nodulated root system. Starch concentration in the lower stem increased continuously from flowering, but in other plant parts declined after early pod-fill. At mid pod-fill, the concentration of soluble sugars in nodules and roots declined and reached a common value in stem sections. Nitrogen (C2H2) fixation decreased rapidly after peaking at early pod-fill. This decline, which was accompanied by loss of lower leaves, occurred in the presence of a high concentration of starch in the stem.

Open Access

Abstract

Close plant spacing in bush snap beans (Phaseolus vulgaris L.), sweet corn (Zea mays L.), and onions (Allium cepa L.) resulted in less weed competition, as measured by crop plant reproductive parts, than wider row spacings. Early weed competition was important in all crops but weed competition at any time reduced onion yields significantly. Corn required 2 weeks and bush snap beans 3 weeks of cultivation after emergence to eliminate losses due to weed competition. Fresh weights of weed at harvest time were significantly less (0.8 kg) in plots of bush snap beans at the narrow row spacing than in plots with the medium and wide spacings (2.8 and 2.4 kg) in an 0.81 m2 area.

Open Access

Abstract

Mulching ‘Puebla 152’ beans with rice hulls to a depth of 4 cm reduced afternoon soil temperature, soil temperature fluctuation, and slowed the loss of soil moisture. These effects were greatest prior to canopy closure. Fresh weight of nodules, roots, stems, leaves, and total plant increased 50%, 38%, 49%, 24%, and 38%, respectively, with mulching, but pod and final seed weight were unaffected. Mulching had little effect on the concentration of soluble and insoluble carbohydrates. N2 fixation rates (C2H2 reduction) were low (≤ 0.6 µmole/plant per hr) but were as much as 3 times higher in mulched than unmulched plants.

Open Access