You can change the axis labels in each subplot individually:
x = linspace(2, 3);
y = sin(2*pi*(x-2)).^2;
figure(1)
subplot(2,1,1)
plot(x, y)
title('Subplot 1')
sp2 = subplot(2,1,2);
plot(x, y)
xt = get(sp2, 'XTick');
xtn = linspace(min(xt), max(xt), 3);
set(sp2, 'XTick', xtn)
title('Subplot 2')
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