Plant Sensitivities

Soil water pH: optimum range between 6.2-6.5.

Soil Texture: sandy to clay loam soils, 6 to 10 inches in depth with moderate organic matter content.

Magnesium (Mg) deficiency: occurs in acid soils (pH<5.4); when not in balance among the cations, K, Ca, and Mg, in the soil and nutrient solution formu-lations; insufficient in Mg concentration is a nutrient solution formulation.

Nitrogen (N) excess: results in vigorous vegetative plant growth, increases incidence of flower abortion, decreases fruit set and reduce fruit quality.

Ammonium (NH4) nitrogen (N): when the major source of N, can result in ammonium toxicity with an increase in the occurrence of blossom-end-rot (BER) in fruit; NH4-N should be less than 25% of the total N in a nutrient solution formulation.

Zinc (Zn) deficiency: occurs due to insufficient Zn and/or excess P in the nutrient solution formulation and in neutral pH soils and high in available P.

Fruit Blossom-end-rot (BER): caused by calcium (Ca) deficiency, usually triggered by plant stress, i.e., moisture, heat, or nutrient element insufficiencies.

Solar Radiation: when low in intensity and/or hours of radiation, plant vegetative growth will be slow and fruit set poor; with high light intensity, poor fruit set and increased occurrence of BER occurs. Best growing conditions are full morning sun, shade from high noon light intensity and partial shading in the late afternoon when light intensity radiation is high.

Carbon dioxide (CO2) enrichment: as a C3 plant, the tomato plant is responsive to the concentration of CO2 in the air surrounding the plant, its growth being enhanced with increasing concentration, but with very high CO2 concentrations, blossom abortion can occur.

Agricultural chemicals: many of commonly used herbicides and pesticides applied to the soil and on agronomic and fruit crops as insecticides and fungicides will adversely affect tomato plant growth even at very low concentrations when being carried in the atmosphere by taking avoidance strategies.

Inconsistency: the tomato plant is unusually sensitive to rapidly changing conditions in the surrounding environment, radiation intensity, air temperature, and humidity, and that in the rooting medium, moisture and temperature levels, primarily affecting fruit set and development.

Fruit Yield and Quality: both fruit yield (size and weight of fruit) and quality are determined by environ-mental and plant status conditions that existed several weeks before maturity.

Plant Wilting: when occurring, even for short periods, will reduce fruit set and yield, increase the incidence of BER, result in blossom abortion, and increase the potential for the occurrence for periods of nutrient element insufficiencies.