Little or no information is available regarding the effects of colored shade nets, different irrigation levels, and the interaction between nitrogen and shading in jalapeño pepper. This study investigated the impacts of colored shade nets, irrigation levels, and nitrogen and shading effects on plant physiology, fruit yield, and the quality of organic jalapeño pepper in Tifton, GA. Using colored shade nets reduced the root zone temperature and light quantity, which enhanced plant vegetative growth. However, regarding fruit yield, shade nets did not improve the marketable fruit number and weight in jalapeño pepper. In addition, shade nets had either no or inconsistent effects between the two seasons on the fruit quality, such as water loss rate, total phenolic contents, total flavonoids, copper-reducing antioxidant capacity and Trolox equivalent antioxidant capacity, capsaicin, and dihydrocapsaicin of jalapeño pepper. Different N fertilizer levels did not significantly impact leaf gas exchange, fruit yield, or quality under shade nets. Nitrogen levels of 179 to 358 kg·ha-1 increased fruit yield and reduced the fruit water loss rate in unshaded conditions. Responses of the jalapeño pepper were inconsistent between years 1 and 2 in terms of plant biomass, leaf gas exchange, fruit yield, and quality because of variations in soil moisture, soil temperature, and evapotranspiration. Considering fruit yield and quality of jalapeño pepper, an irrigation level of 75% crop evapotranspiration can effectively save water. The shading net did not enhance jalapeño pepper fruit yield. Under open-field conditions, jalapeño pepper treated with 179 to 358 kg·ha-1 N (from organic fertilizer) resulted in the highest fruit yield. However, inconsistent responses between the two growing seasons while using different colored shade nets and irrigation levels require further investigation.

INDEX WORDS: Abiotic stress, leaf gas exchange, shade nets, jalapeño pepper, organic agriculture