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Although water conservation programs in the arid southwestern United States have prompted prudent landscaping practices such as planting low water use trees, there is little data on the actual water use of most species. The purpose of this study was to determine the actual water use of two common landscape tree species in Tucson, Ariz., and water use coefficients for two tree species based on the crop coefficient concept. Water use of oak (Quercus virginiana `Heritage') and mesquite (Prosopis alba `Colorado') trees in containers was measured from July to October 1991 using a precision balance. Water-use coefficients for each tree species were calculated as the ratio of measured water use per total leaf area or per projected canopy area to reference evapotranspiration obtained from a modified FAO Penman equation. After accounting for tree growth, water-use coefficients on a total leaf area basis were 0.5 and 1.0 for oak and mesquite, respectively, and on a projected canopy area basis were 1.4 and 1.6 for oaks and mesquites, respectively. These coefficients indicate that mesquites (normally considered xeric trees) use more water than oaks (normally considered mesic trees) under nonlimiting conditions.
Abstract
Four mid-season inbreds of sweet corn (Zea mays L.) were subjected to moderate or high soil moisture stress at tasseling, silking, or 2 weeks after silking. Soil moisture stress two weeks after silking was associated with a significant increase in the incidence of stalk rot symptoms 80 days after planting. Stalk rot and the percent seed-borne Fusarium moniliforme Sheld. were highly correlated. Stress at silking significantly reduced both yield components and seed quality attributes. Seed size distribution was influenced by the occurrence of water deficits, while the percent marketable seed was not.
Abstract
‘Kootenai’ and ‘Sandpoint’ tomatoes (Lycopersicon esculentum Mill.) are dwarf, ultra-early cultivars intended for use in cool and short growing season areas. ‘Kootenai’ is named for an Indian tribe of northern Idaho and ‘Sandpoint’ is named for the city of Sandpoint where it was first selected.
Abstract
Diethanolamine and potassium salts of maleic hydrazide (MH) were applied to plants of ‘Yellow Sweet Spanish’ onion (Allium cepa L.) exhibiting maturity ratings of 0, 25, 50, and 100% green tops down. The K formulation of MH was equal to the diethanolamine formulation in sprout control of onions in storage. Lower application rates resulted in lower bulb residues; however, there were no consistent differences in bulb residues among the maturity treatments. Concentrations of MH were lowest in mature outer scales. Maleic hydrazide applications significantly reduced sprouting during storage, had no effect on the percentage of bulbs with storage rot, and reduced respiration rates and weight loss of bulbs stored at 10°C, but had no effect on respiration rate and only slightly reduced weight loss of bulbs stored at 4°. Root growth occurred on nontreated bulbs at both 4 and 10°, while root development was inhibited in MH-treated onions.