Figure 5. Average NDVI for three periods of the year (Q_1: Julian dates 1-153, late winter-spring;
Q_2: Julian dates 154-237, summer; Q_3: Julian dates 238-365, fall-early winter) for the four land use categories: irrigated crops (I), non-irrigated crops (NI), grasslands (RL) and Conservation Reserve Program (CRP). Different letters indicate significant differences (ANCOVA, p<0.001, see Table 2).