Relationships between extractable chlorophyll and SPAD values in muskmelon leaves

Chlorophyll content of muskmelon is usually determined by destructively sampling plant leaves. However, a hand-held SPAD-502 Chlorophyll Meter provides rapid and nondestructive measurements of leaf chlorophyll content. This study aims to determine the relationships between extractable chlorophyll and SPAD values in muskmelon leaves. SPAD readings were significantly related to extracted chlorophyll of muskmelon leaves both on a fresh weight and leaf area basis. Quadratic equations best described their relationships. At 10 days after nitrogen (N) fertilization, the r(2) values for chlorophyll a, b, and total chlorophyll on a fresh weight basis were 0.84, 0.86, and 0.85, respectively, while on a leaf area basis, r(2) values were 0.92, 0.95, and 0.94, respectively. At 17 days after fertilization, the r(2) values, for chlorophyll a, b, and total chlorophyll on a fresh weight basis were 0.57, 0.49, and 0.56, respectively, while on a leaf area basis, r(2) were 0.72, 0.67, and 0.71, respectively. Therefore, the SPAD-502 Chlorophyll Meter can be used to measure chlorophyll content of muskmelon leaves.