Fig 7. Plotting a PCA biplot shows 93.49% of the data’s variability.

For example, the cosine angle indicates correlation between traits; acute and obtuse angles indicate positive and negative associations; while a right angle between two vectors of variables indicates no correlation. An example of a biplot is shown below. It shows the relationships between various parameters such as grain yield (GY) and biological yield (BY), as well as other factors such as plant height (PH) and the number of fertile tillers (NFT), shoot length (SL) and the number of spikelets per spike (NSPS) and number of grains per spike (NGPS), 1000 grain weight (1000GW), transpiration rate (Tr), photosynthetic rate (Pr), water use efficiency (WUE), Chl a (Chlorophyll a), Chl b (Chlorophyll b), EL% (Electrolyte leakage %), H₂O₂ (Hydrogen Peroxide), CAT (Catalase), POD (Peroxidase), SOD (Superoxide Dismutase) of wheat crop under drought at tillering (DTS), flowering (DFS), and grain filling stages (DGFS) and full irrigation as control (CK) by using three biochar treatments such as BC₀ = control, BC₁ = 3%, and BC₂ = 5%.