Steering nitrogen fertilization by means of portable chlorophyll meter reduces nitrogen input and improves quality of fertigated cantaloupe (Cucumis melo L. var. cantalupensis Naud.)

BACKGROUND: Farming is considered one of the main causes of land degradation and underground water pollution. The increased availability of agricultural inputs caused a dramatic raise of yields, which reflected soil fertility spoilage and overuse of fertilizers. Therefore horticultural practices improvement has to consider the correct nitrogen (N) management. In this study we report our results on the application of an optical diagnostic system (N-tester) to guide N fertilization in muskmelon (Cucumis melo L.) over a three years trial. Results on fresh and post-harvest quality are also presented. RESULTS: Fertilization events mirrored increases in N-tester values along the season, and a significant linear relationship (R2 = 0.628) was observed between N-tester readings and leaf chlorophyll content. The N-tester guided fertilization treatments, were charachterised by yields comparable to the control, but significantly lower applications of N (down to 17 to 66% of the N distributed in the control). Moreover, N-tester treatments presented fruits with higher sugar content. This was true also after storage, when N-tester fruits also presented reduced weight loss associated with lower transpiration and ethylene emission rates. CONCLUSIONS: Through the use of ‘spy plots’ kept at optimal nutritional status, and the adoption of threshold for N application throughout the growing cycle of muskmelon, we significantly reduced the N supply. Therefore, a correct application of N-tester allowed to reduce plant N requirement and increase fruit sugar content and storability, without any harm to yield.