Effect of root and foliar application of amino acids on the growth and yield of greenhouse tomato in different fertilization levels.

Tomato plants (cv. ‘Belladonna’) were grown on the soil in an unheated greenhouse at the farm of Aristotle University of Thessaloniki, Greece. The area of the greenhouse was divided in plots, where 3 levels of pre-planting fertilization were applied: i) conventional, ii) reduced by 20% and iii) reduced by 40%, in 4 replications each. On the day of transplanting, as well as after 4, 6, 8, 10 and 12 weeks Amino16 ® was applied either in roots or sprayed foliar in 4 combinations (% in roots + % foliar): i) 0 + 0, ii) 0.3 + 0.9, iii) 0.9 + 0.3 and iv) 2.7 + 0. Amino16 ® is a hydrolyzed protein solution containing 11.3% L-amino acids, 4% total N and 25% organic matter. During cultivation, observations regarding the plant height, node and flower’s number as well as the fruit setting were recorded. During harvesting period, each fruit was weighted, observations regarding malformation, insect infestation and fruit cracking were recorded and finally fruits were graded according to the commercial standards in class I, class II or nonmarketable. The whole harvesting period of 66 days was divided into two sub-periods: early and normal. The results showed that in conventional fertilization, the application of 0.3% Amino16 ® in roots + 0.9% foliar increased fruit weight of both class I and class II, as well as of either early or normal period. Under the same treatment, a trend for marketable yield increasing was obvious, although not significant. In reduced by 20% fertilization, the application of 0.3% Amino16 ® in roots + 0.9% foliar increased marketable yield of early period. On the other hand, in reduced by 40% fertilization, the application of 2.7% Amino16 ® in roots + 0% foliar increased both total and marketable yield and this was due to the increased fruit number. It could be concluded that the application of amino acids has appreciable effects on the yield of greenhouse tomato and its effective application way (through roots or foliar) dependents on pre-planting fertilization level.