Nitrogen fertilization methods affect growth of sweet pepper (Capsicum annuum L.) transplants

The objective of this study was to evaluate methods of nutrient addition to the substrate in on-farm sweet pepper transplants production systems. Two fertilization methods: (i) fertirrigation four times during transplant growth and (ii) premixing mineral N fertilizer with the substrate, were evaluated together with three N application rates: 0, 600 and 1200 mg NL-1 on sweet pepper seedlings growing in planter flats with cells of 57 cm(3), on a mix of Sphagnum peat, compost (40%), perlite and vermiculite as growing medium. Leaf area (LA), height and stem diameter (HS, SD), partitioned and total fresh and dry weight were measured at transplanting (57 days after sowing). Partitioned and total dry matter, specific leaf area (SLA), leaf area ratio (LAR), leaf area duration (LAD), net assimilation rate (NAR), absolute, and relative growth rates based on fresh and dry weight (AGRf, AGRd, RGRf, RGRd), and absolute and relative leaf expansion rates (ALER, RILER) were calculated. The application of 600 mg NL-1 premixed in the growing medium led to better quality transplants at 57 days. There were strongly significant fertilization methods x application rate interactions for variables such as LA and growth rates. N applied at a rate of 1200 mgL(-1) only led to slight improvement of some of the growth parameters when it was fertirrigated. In conclusion, premixing mineral N fertilizer in the substrate mix prior to cell seeding improved the efficiency of N use in the system by reducing the application rate for optimum transplant quality.