The use of micro-computer programs as a management teaching aid has enabled horticulture students to understand economic relationships involved in the production of apples (2, 3), strawberries (4), and selected greenhouse crops (7). By incorporating uncertainty about final crop yield and selling price, these models can be used to generate information about the relative “riskiness” of crop production, where risk is measured by the probability that total revenue will exceed total costs (1, 8). The objective of this research was to develop a micro-computer model that would assist students and/or producers in understanding the economic relationships between yield and price variability and overall risk.
Transplants of asparagus (Asparagus officinalis L.) were grown in sand culture under varying ratios of NO3 and NH4. Maximum growth occurred in a nutrient solution with a N ratio of 75% NO3 – N and 25% NH4 – N. Growth was significantly reduced when the N composition was either 100 or 75% NH4 – N. CaCO3 reduced ammonium toxicity but also reduced seedling growth.
Seedlings of tomato (Lycopersicon esculentum Mill.) were exposed to winds of 1,340 cm/sec (for 10 and 20 minutes) and wind-plus-sand (10 and 20 minutes; abrasive flux rate, 6 g/cm per minute). Exposing plants to wind alone for 10 and 20 minutes had no effect on stem or leaf anatomy, although 20 minute winds caused desiccated lesions on leaves. Tomatoes, sandblasted for 10 or 20 minutes, developed a secondary endodermis under wounded tissue with wound periderm developing 2 days after wind treatment. Leaf, palisade cell, and leaf midrib thicknesses in plants exposed to 20 minutes of wind-plus-sand were greater than those of the controls. Stems of plants sandblasted for 20 minutes developed an elongated layer of chlorenchyma below the epidermis 21 days after exposure; the layer was doubled that of the controls. Dry weight and net photosynthetic rates were reduced significantly in all plants by all treatments compared with controls except on day 1 after plants were exposed to wind for 10 minutes. Net photosynthetic rates were not significantly different 5 days after treatment, and net respiration rates were not significantly different on either day 1 or 5.
Pumpkins are Ohio's third-largest fresh-market vegetable crop. Many non-traditional growers are planting pumpkins to increase gross income. Experienced growers have noticed that new producers are successful with low input. Are intensive production practices needed for a good crop? High and low input production schemes were studied, over 3 years on pumpkin yield and quality. High input consisted of Furadan at planting, reflective mulch, trickle irrigation, and a routine fungicide and insecticide spray program. Low input consisted of no mulch, no supplemental irrigation, and a reduced fungicide and insecticide program. The number of insecticide plus fungicide sprays for high vs. low input were: 10 vs. 5 in year 1; 5 vs. 3 in year 2; and 12 vs. 8 in year 3. Number and weight of marketable orange fruit in high-input plots were significantly higher than low input plots in year 1 and 3. Plastic mulch conserved soil moisture and resulted in 91% plant stand in high input vs. 57% in low input in year 1. The only year without a significant yield difference was when the difference in pesticide sprays was two. High input is suited for retail markets where the expectation is good yields of high quality pumpkins. Wholesale producers can probably get by with reduced inputs in certain areas.