highly significantP < 0.01
Among these modules, the brown ( r = − 0.53, P = 3.8 × 10 − 5 ), darkgreen ( r = − 0.6, P = 1.6 × 10 − 6 ), and red ( r = − 0.45, P = 6.4 × 10 − 4 ) modules showed a highly significant negative correlation with the cold tolerance of alfalfa ( P < 0.01).