Effects of nitrogen pre-treatment of transplants from in vitro produced potato plantlets on transplant growth and yield in the field

In vitro propagated potato plantlets, cultivars Gloria and Spunta, were pre-treated with 10 or 40 mg nitrogen per plant before transplanting to the field to determine after-effects of nitrogen on field performance of these transplants in two experiments. Yield, ground cover (GC), accumulated intercepted radiation (AIR), radiation use efficiency (RUE) and harvest index (HI) were assessed. Spunta had higher GC, AIR, total dry matter and tuber fresh and dry weights but lower RUE and HI than Gloria at final harvest. Nitrogen pre-treatment had no clear effect on plant growth at the end of the transplant production phase or during early field growth. Later, higher nitrogen pre-treatment resulted in a slightly higher GC and AIR. In one experiment this resulted in a significantly higher yield. Pre-treatment did not affect HI at the end of the season. Nitrogen pre-treatment can improve seasonal light interception of plantlets of transplant crops from early cultivars.