Steering nitrogen fertilisation 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 has led to a dramatic rise in yields, which has resulted in soil fertility spoilage and overuse of fertilisers. Therefore horticultural practice improvement must consider appropriate nitrogen (N) management. This paper reports results on the application of an optical diagnostic system (N-tester) to guide N fertilisation in muskmelon (Cucumis melo L.) over a 3 year trial. Results on fresh and postharvest quality are also presented.

RESULTS

Fertilisation events mirrored increases in N-tester values during the season, and a significant linear relationship (R(2) = 0.628) was observed between N-tester readings and leaf chlorophyll content. The N-tester-guided fertilisation treatments were characterised by yields comparable to the control, but with significantly lower applications of N (down to 17-66% of the N distributed in the control). Moreover, the N-tester treatments yielded fruits with higher sugar content. This was also true after storage, when N-tester fruits also showed reduced weight loss associated with lower transpiration and ethylene emission rates.

CONCLUSION

Through the use of 'spy plots' kept at optimal nutritional status and the adoption of a threshold for N application throughout the growing cycle of muskmelon, the N supply was significantly reduced. Therefore a correct application of N-tester allowed the plant N requirement to be reduced and the fruit sugar content and storability to be increased without adversely affecting the yield.