Ntrogen fertilizer management practices to enhance seed production by 'Anaheim Chili' peppers

The effects of six applied N treatments differing by rates and frequencies of application on the yield and quality of pepper (Capsicum annuum var. annuum L. 'Anaheim Chili') grown for seed was studied. The timing of N applications was based on crop phenology, leaf petiole nitrate-nitrogen concentrations (NO3-N) minimum thresholds, and scheduled calendar applications of fixed amounts of N. Solubilized NH4NO3 was applied through a trickle-irrigation system to ensure uniform and timely applications of N. Rate of mature (green and red) fruit production was unaffected by any treatment except weekly applications of 28 kg.ha-1 of N, which stopped production of mature fruit before all other treatments. Early season floral bud and flower production increased with increasing amounts of N. The two highest total N treatments produced more floral buds and flowers late in the season than the other treatments. Total fruit production was maximized at 240 kg N/ha. Differences in total fruit production due to frequency of N application resulted at the highest total N level. Red fruit production tended to be maximized with total seasonal applied N levels of 240 kg.ha-1 and below, although weekly applications of N reduced production. Total seed yield was a function of red fruit production. Pure-live seed (PLS) production was a function of total seed production. Nitrogen use efficiency (NUE) for red fruit production also decreased with N rates >240 kg.ha-1, but PLS yield and NUE decreased in a near-linear fashion as the amount of total seasonal applied N increased, regardless of application frequency. Season average NO3-N (AVE NO3-N) values >4500 mg.kg-1 had total seed and PLS yields less than those treatments <4000 mg.kg-1. Six-day germination percentage was reduced with weekly N applications of 14 kg.ha-1. Seed mass was reduced with weekly N applications of 28 kg.ha-1. Final germination percent, seedling root length and weight, and field emergence were unaffected by any of the N treatments. These findings indicate that different N management strategies are needed to maximize seed yield compared to fruit yield and, therefore, there may be an advantage to growing 'Anaheim Chili' pepper specifically for seed.