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  • Author or Editor: John McGrady x
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Transplant nutrient conditioning for desert cauliflower (Brassica oleracea var. botrytis) production has enhanced transplant shock recovery, earliness and increased yield; partial defoliation and traditional hardening may also be effective. `Snowcrown' seedlings fertilized with 50, 150 or 450 mg N 1-1 were clipped to remove 0, 45, 60 or 98% of their leaf area. High root-shoot ratios in the 98% defoliated plants may have resulted in elevated transpiration in new leaves but neither high N conditioning nor defoliation enhanced survival or increased yield. Seedlings raised with 100, 200 or 400 mg N 1-1 were hardened with 4 water/fertilizer withholding regimes prior to transplanting. Non-hardened transplants within each fertilizer regime outyielded hardened transplants. Use of sprinkler or furrow irrigation for day/night establishment of hardened or conditioned transplants will be evaluated.

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Asparagus (Asparagus officinalis) has great potential for production in the southwestern desert areas. Light, moderate and heavy harvest regimes were imposed on a one year old planting of `Mellowland Select' to determine the optimum duration of Spring harvest. There were no differences in mean spear weight or number of spears per plant in response to cutting pressure in 1987 or 1988. In 1989 both the light and heavy cutting regimes resulted in spears weighing 2.0 and 1. 5 grams less, respectively, than the moderate treatment and in fewer spears per plant. Consequently, 587 and 670 fewer kg/ha were produced in the lightly and heavily harvested plots in the third year. Total storage root carbohydrates were higher in the moderately harvested plots prior to harvest and again after fern production resumed in the third year. 1990 harvest data and implications for fall harvested or double-harvested asparagus will be discussed.

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Abstract

Pregerminated (PG) chile pepper (Capsicum annuum L.) seed was fluid-drilled in gels on three dates (early to late spring). Plants grown from PG seed emerged earlier than those from dry seed, and plant growth was enhanced (including earlier flowering), but the fruit yields were not affected. In the first planting date in cold soils, PG slowed emergence and the hypocotyls tended to coil within the gel. In a companion test, pre-soaking seed improved emergence, growth, and yield compared to plants from dry seed. Adding P to the soaking solution enhanced emergence, early plant growth, and plant P, but decreased fruit yields. Phosphorus added to the gel water of hydration increased seedling growth, but did not significantly affect fruit yields.

Open Access

Lettuce (Lactuca sativa L.) seed germination is inhibited at temperature higher than 25-30C. The extent of this inhibition varies between seed lots. Our objective was to determine how the season during which seed develops affects the ability of seeds to germinate and establish a stand at high temperatures. Lettuce seed, `Empire', was produced during 2 summers and 2 winters (1988 and 1989) in Yuma, AZ. These seeds were germinated at 20, 25, 30 or 35C in petri dishes or in growth pouches to determine percent germination or root lengths, respectively. Electrical conductivity of seed leachates was measured. Field emergence of seeds was tested with early fall plantings in Yuma, AZ. Percent seed germination was greater and root lengths were longer for the seeds produced in summer than in winter. Conductivity will be correlated with relative tolerance to high temperatures of the different seed lots. In the field, percent emergence of seed lots from summer and winter averaged 60% and 38%, respectively.

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Lettuce (Lactuca sativa L.) seed germination is inhibited at temperature higher than 25-30C. The extent of this inhibition varies between seed lots. Our objective was to determine how the season during which seed develops affects the ability of seeds to germinate and establish a stand at high temperatures. Lettuce seed, `Empire', was produced during 2 summers and 2 winters (1988 and 1989) in Yuma, AZ. These seeds were germinated at 20, 25, 30 or 35C in petri dishes or in growth pouches to determine percent germination or root lengths, respectively. Electrical conductivity of seed leachates was measured. Field emergence of seeds was tested with early fall plantings in Yuma, AZ. Percent seed germination was greater and root lengths were longer for the seeds produced in summer than in winter. Conductivity will be correlated with relative tolerance to high temperatures of the different seed lots. In the field, percent emergence of seed lots from summer and winter averaged 60% and 38%, respectively.

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Abstract

Experiments were conducted to evaluate the effect of fresh and aged conifer barks on galling by the root-knot nematode [Meloidogyne incognita (Kofoid and White) (Chitwood)] on tomato (Lycopersicon esculentum Mill.) roots. Fresh bark (stored at sawmill) exhibited significant nematicidal activity (reduced galling) when used as a medium component [50% or 75% with sand (v/v)]. Galling on tomatoes grown in aged bark (used as a culturing medium for tomatoes for 5 years) was extensive. When 10% or 20% fresh conifer bark was mixed into beds, galling was less extensive on tomato roots than on roots from tomatoes grown in an unamended medium. The nematicidal property of conifer bark diminished during long-term use. Increases in medium pH, which occurred during continuous cropping, could have contributed to the reduced nematicidal activity with time.

Open Access

Abstract

Experiments were conducted in 1979 and 1980 to evaluate anticrustant (H3PO4 and Nalco 2190) effects on stand establishment, growth, and yield of chile pepper (Capsicum annuum L.). While plant stands and fruit yield were not increased by applying H3PO4 over the seeded row in 1979, hypocotyl stress of germinants was reduced. Stands and P content in 1980 were not increased by H3PO4 or Nalco 2190 treatments 1 month after emergence, but plant height was increased significantly by both anticrustants. Yields of fresh green chile peppers were not enhanced by treatments. While germinant stress could be reduced by using anticrustants, it was concluded that a factor other than crusting was limiting chile seedling growth in southern New Mexico.

Open Access

Three main plot production systems - conventional, organic and mixed organic/conventional - were established in a fixed location at the Yuma Valley Agricultural Center in September 1989. A split plot treatment of a liquid biological soil conditioner was applied to one-half of each main plot. Chemical or organic fertilizers were applied to give 225 kg N/ha for the growing season. During a two-year transition plant mineral nutrient content did not differ greatly. However, nitrate and total nitrogen were significantly lower in the organically grown lettuce. Plant nitrate content was also enhanced by the soil conditioner as was early head weight. A greater number of heavier heads was harvested early from the chemically fertilized plots. Soil microbial populations did not reflect an effect of fertilizer treatments in the first season; there were trends for population fluctuations in response to sidedressing in the second and third seasons. No significant insect activity was observed and no pest control was necessary. Higher populations of soil pathogens were detected on mature lettuce roots in the conventionally fertilized plots.

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