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Growth chamber tests demonstrated that alfalfa (Medicago sativa L.) residue is toxic to cucumber (Cucumis sativus L.) seed germination and seedling growth. Ground alfalfa roots at 0.5% (w/w, dry weight) inhibited germination when added to the growing medium. Alfalfa roots at 0.5% were also toxic to pregerminated cucumber seed. However, cucumber seedlings grew normally if this same medium was watered and incubated for >1 day before planting. Alfalfa particle size in media influenced cucumber performance, with the intermediate size (1 to 2 mm) being lethal to cucumbers.
Abstract
Cone, belt, and baffle planters built to fit on standard Planet Jr. planting units, were evaluated for vegetable plot seeding. On the basis of field tests with cabbage, cucumber, and lettuce seed, the belt planter was preferred. The cone planter had difficulty in transferring seed from the cone plate to the delivery tube and the baffle planter did not seed cabbage and lettuce uniformly.
Abstract
Substandard color was encountered in experimental frozen samples of pea (Pisum sativum L.) produced in the San Luis Valley, Colorado in 1973 and 1974. Light green and blond peas were mixed with normal dark peas rendering the samples unacceptable. Peas planted in April, 1975 had satisfactory color regardless or irrigation schedule or tenderometer reading at harvest. May-planted peas generally had inferior color and this was aggravated by frequent irrigations and over maturity.
Abstract
The 3 common criteria used to express yields of pickling cucumber cultivars are fruit number, dollar value, and kilograms per hectare. In the current study, number offrait was shown to have the least fluctuation over the time when a single destructive harvest would be made and is suggested as the most accurate criterion for comparing yield of pickling cucumber cultivars.
Abstract
Cucumber (Cucumis sativus L.) irrigation scheduling was studied during the 4 years of 1983-1986. Tensiometers were used during the first year to determine when to irrigate, and the USDA irrigation scheduling program was used to determine the amount of water to apply. The data from the first year’s study indicated that the plants had not been stressed; therefore, the following year, estimates of the available water depletion were made with the USDA irrigation scheduling program, with tensiometers used only for comparison. After 4 years of study, we concluded that the best combination of high yield, high water use efficiency, and fewest number of irrigations was obtained if cucumbers were irrigated when the original scheduling program determined that 40% of the available water was depleted, applying only 70% of the water that the program indicated was required. This signaled that the program was overestimating the rate at which water was being depleted. Therefore, as a final step, a revised set of cucumber coefficients that approximated daily evapotranspiration (ET) more closely was determined. When using the revised coefficients, cucumbers should receive the exact amount of water called for by the irrigation program.
A 3-year irrigation scheduling study on carrots (Daucus carota L.) was conducted at the Colorado State Univ. Horticulture Research Center near Fort Collins to determine the irrigation schedule that produced the best combination of high water use efficiency and marketable yields with the least amount of water and fewest irrigations. This study used an irrigation scheduling program developed by the U.S. Department of Agriculture/Agricultural Research Service with crop coefficients calculated for carrots. Maximum carrot production and water use efficiency were obtained when the scheduling program simulated a 30-cm rooting depth at planting, increasing linearly to 60 cm in 75 days. Best yields and water use efficiency were attained by irrigating whenever 40% of the available water in the root zone had been depleted. The computer program for irrigation scheduling is available on diskette from the authors.
Roots of acorn squash were washed from soil cores, dried and weighed. The cores were taken in a pattern about individual plants to reflect the roots present in each selected zone at different periods during the season. A different plant was sampled at each period so that there would be no effect from previous sampling. The root weights were multiplied by factors commensurate with the volume of soil represented by each core sample. Two years data have indicated that irrigation level effects the size of the root system but not its distribution. Density of roots was always greatest in the top 15 cm of soil and this zone of the greatest density progressively moved out from the center of the plant with time. Pattern of root distribution was not effected by plastic mulch, bare ground, trickle or furrow irrigation treatments. Root distribution was the same on all sides of the plant.
Abstract
Two onion (Allium cepa L.) irrigation scheduling procedures were compared in field studies over a 3-year period. The McSay–Moore model uses volume of distilled water evaporated from calibrated Bellani atmometers as a basis for predicting irrigation. This model tells when to irrigate, but not how much to apply. The ARS/USDA model uses energy and aerodynamic equations to make estimates of evaporation rates from meteorological data. This model not only predicts when to irrigate, but also the amount to apply. Given the conditions for these experiments, onion yields and water use efficiencies were greater with the ARS/USDA than with the McSay–Moore model.
An irrigation scheduling program has been developed for zucchini squash that produced high yields and high water use efficiency with, a minimum number of irrigations. The irrigation program is based upon a soil water balance model developed by the USDA. This irrigation program is available in diskette form and may be used with any IBM compatible personal computer provided wind run, temperature, solar radiation, humidity and precipitation data are available.
Irrigation scheduling programs were developed for cabbage and zucchini squash that produced high yield and water-use efficiency with a minimum number of irrigations. The irrigation programs are based on a soil water balance model developed by the USDA. The procedure involved selecting irrigation programs developed for similar crops and using them as standards for cabbage and zucchini for three growing seasons. The treatments involved irrigation levels higher and lower than the standard. After the third year, the best treatment for each year was selected. Coefficients for the standard model then were adjusted by trial and error to produce a program that called for the same number of irrigations and the same amount of water as the best-performing treatment when using the same weather data. These revised programs for cabbage and zucchini squash are available on computer disks and may be used on any IBM compatible PC provided wind, temperature, solar radiation, humidity, and precipitation data are available,