Available at: https://digitalcommons.calpoly.edu/theses/3166
Date of Award
6-2025
Degree Name
MS in Agriculture - Crop Science
Department/Program
Horticulture and Crop Science
College
College of Agriculture, Food, and Environmental Sciences
Advisor
Dr. Ashraf Tubeileh
Advisor Department
Horticulture and Crop Science
Advisor College
College of Agriculture, Food, and Environmental Sciences
Abstract
Nitrogen (N) is an essential nutrient for plant growth and is often a limiting nutrient in cropping systems. An estimated half of applied N fertilizers are lost from cropping systems by processes that can be environmentally destructive, such as leaching and volatilization, and cause economic loss for growers. Effective N biofertilizers offer a means to mitigate the need for high inputs of synthetic N. The objectives of this study were to determine the effects of leaf inoculation with the N-fixing bacteria, Methylobacterium symbioticum, in combination with different rates of urea-N fertilizer on the physiology and yield of dent corn (Zea mays L.) and Romaine lettuce (Lactuca sativa L.) crops. Plants were grown in 12 L pots using a loamy sand soil and were organized according to a randomized complete block design with eight replicates for corn and 10 replicates for lettuce per treatment combination. The N fertilizer with the biofertilizer treatment significantly increased the corn leaf surface area, shoot and total aboveground dry matter production of the corn plants. The N fertilizer with the biofertilizer treatment significantly increased the total dry matter production of the lettuce plants. The chlorophyll content and fluorescence of the lettuce leaves were significantly greater with the biofertilizer than without the biofertilizer at 0 kg N/ha. Overall, the M. symbioticum may be effective with lower rates of N to increase the sustainability of conventional lettuce and corn crop production systems. Further research and field studies are required to study the effect of this bacteria with lower N application rates, different N sources and different crops.