mango.

David_WM says...
Regarding Plant Breeders Rights, have a look at this web page. It says that there is no international system and that PBR needs to be registered in each country you are concerned with.
http://www.ipaustralia.gov.au/get-the-right-ip/plant-breeders-rights/international-pbr/
Do you want to tell us about your variety? It would be interesting to hear what you've done.
Regarding the nitrogen and boron levels, in commercial situations farmers will get leaf analysis done in order to determine the leaf mineral concentration and then alter their nutrient program to suit. Leaf dry weight concentration of Nitrogen is aprox 1.0 -1.5% as a target guide. For non commercial activities this is probably too expensive and you need to guess based on observation of the tree. Too little nitrogen any the leaves yellow, too much and you get bright green. Excessive nitrogen has a negative effect on fruit quality, less coloration and more prone to disease. Too little boron and you get deformed leaves, new leaves are deformed sickle shaped, maybe holes surrounded by a light green halo.Fruit may have cracks that open up, and get brown discolouration of flesh. Too much boron may have dark spots on leaf margins that join together when severe leading to the edges of the leaves dying off.