%borders should be used. 
%https://www.mathworks.com/matlabcentral/fileexchange/50390-borders

%Enter Directory
fname='Directory';
filename='wheat_irr.nc';
ncdisp(fullfile(fname,filename));
wheat_irr =ncread(fullfile(fname,filename),'Band1');
filename='wheat_rain.nc';
ncdisp(fullfile(fname,filename));
wheat_rain =ncread(fullfile(fname,filename),'Band1');
wheat_coverage=wheat_irr+wheat_rain;
wheat_coverage(wheat_coverage==0)=NaN;

%map it for wheat_irr and wheat_rain using the following code
Var=wheat_coverage;
Var=Var';
Var(Var==0)=nan;
h1=imagesc(linspace(-180,180,720),linspace(-90,90,360),Var);
set(h1,'alphadata',~isnan(Var))
colormap(gca,'jet')
set(gca,'YDir','normal')
ylabel('Latitude','fontsize',15)
xlabel('Longitude','fontsize',15)
hold on
h=colorbar('location','Eastoutside');
hold on
borders('countries','nomap','color','black','LineWidth', 1.5)
