Role of Nitrogen in Melon Production

It is thus one of the most important nutrients required for high yields.

Nitrogen and yield

Crops remove around 3.8 kg for every ton of fruit produced. Rates of 180 kg/ha can supply 50t/ha field yields (cv. Eldorado 300 - Melon, Brazil).

Nitrogen and sugar content

High nitrogen rates of this magnitude will also boost leaf growth and sugar synthesis, improving fruit quality (cv. Eldorado 300 - Melon, Brazil).

Nitrogen and shelf life

Too much nitrogen at later stages of growth can spoil fruit quality by increasing the level of blemish on the rind and encouraging fruit rot. Thus, it is important to confirm rates and timing following local trials that take into account the need for high yield, but also good quality fruit (Charentais cv. Phoenix - Cantaloupe, France).

Nitrogen source and yield

Nitrogen form is critical to maintain a good balance between ammonium and nitrate forms to maintain fast growth and good crop productivity. Trials confirm significant reductions in N-uptake by leaves and yield losses from use of fertilizers with a too high proportion of ammonium compared to nitrate (cv. Sugar Baby - Watermelon, USA).

Nitrogen form and cation uptake

In the same two independent trials, where ammonium-N was the main N-source, the ammonium was preferentially taken up compared to potassium, magnesium and, more significantly, calcium and magnesium, reducing levels of these important nutrients in the crop. Optimal NO3:NH4 ratios for best  crop performance in the scientific literature range from 5:1 to 3:1.

N-form - sodium and potassium uptake

Under saline conditions, nitrate-N tends to limit sodium uptake and ammonium- N tends to favor greater uptake of sodium. This in turn reduces the uptake of ions such as potassium (cv. Summet - Muskmelon, USA).

See more on Melon Growth Stages.

General guidelines for Nitrogen application

As nitrogen is essential for high yields, timing is just as important, since an excess of nitrogen at flowering can reduce flower numbers, leading to reductions in fruit set. In addition, too much of this nutrient at later stages of growth can spoil fruit quality by increasing the level of blemish on the rind and encouraging fruit rot. Nitrogen form is also critical to maintain fast growth and good crop productivity. Yield losses occur and quality deteriorates when N-fertilizers with a high proportion of ammonium compared to nitrate are used.

Nitrogen deficiencies in melon

Leaves turn pale green, starting with the oldest leaves first. The stems become thin, hard and fibrous. Flowers are more readily aborted, resulting in poor fruit set. Fruits are small, pale green and deformed especially at the blossom end. It is thus important that N-supply is not limiting prior to flowering, or growth and yield will be adversely affected.