Correlation analysis of growth, yield, and quality traits in maize (Zea mays L.) hybrids under different plant densities

The study aimed to analyse the correlation relationships among growth, yield, and kernel quality traits in two yellow maize hybrids (DKC6050 and DKC6777) under four plant densities (66,666; 80,000; 100,000; and 133,333 plants ha −1 ) during the fall season of 2023 at the Agricultural Research Station – University of Kirkuk. The results showed that hybrid DKC6777 outperformed in number of kernels row −1 , 500 kernel weight, and plant height, achieving the highest yield of (8.03 t ha −1 ). In contrast, DKC6050 was earlier in silking and responded better under moderate plant densities. The highest density (133,333 plants ha −1 ) recorded the greatest kernel yield (8.74 t ha −1 ), despite reductions in some single yield components, reflecting a compensatory effect due to increased plant number. Correlation results at the highest density showed significant associations between kernel yield and plant height (r = 0.890 * ) and number of kernels row −1 (r = 0.863 * ). At 100,000 plants ha −1 , kernel yield was strongly correlated with 500-kernel weight (r = 0.969 ** ), number of kernels row −1 (r = 0.940 ** ), and plant height (r = 0.950 ** ). These strong relationships persisted at 80,000 plants ha −1 . However, the 66,666 plants ha −1 density showed the highest number and strength of correlations, particularly between yield and 500 kernel weight (r = 0.984 ** ) and number of rows ear −1 (r = 0.982 ** ). This suggests that medium to low plant densities may be optimal for achieving trait integration and enhancing the predictability of yield, which is valuable in breeding programs based on indirect selection.