Effect of Different Maize (Zea mays)/Cowpea (Vigna unguiculata) Intercropping Patterns and N Supply on Light Interception, Physiology and Productivity of Cowpea

The objective of this experiment was to assess the impact of different planting patterns on light availability for cowpea within the intercrop canopy, as well as to evaluate the corresponding effects on cowpea's physiological characteristics and grain yield in maize/cowpea intercropping systems. The experiment utilized a randomized complete block design with four replicates and included six treatments: sole cowpea with 40 kg N ha⁻¹ (T1) and 80 kg N ha⁻¹ (T2), simultaneous sowing of maize and cowpea with 40 kg N ha⁻¹ (T3) and 80 kg N ha⁻¹ (T4) and cowpea sown 3 weeks after maize with 40 kg N ha⁻¹ (T5) and 80 kg N ha⁻¹ (T6). Results showed that sole cowpea had higher light interception and leaf area index than intercropped maize/cowpea, regardless of sowing date and nitrogen supply. The highest photosynthetic rates of cowpea were observed in the intercropping maize/cowpea sown simultaneously with 40 kg N ha⁻¹ and sole cowpea with 80 kg N ha⁻¹. The water use efficiency of cowpea was found to be higher when intercropped with simultaneously sown maize, regardless of nitrogen supply, with values of 3.23 μmol CO₂/mmol H₂O and 3.3 μmol CO₂/mmol H₂O for treatments T3 and T4, respectively. Moreover, the highest cowpea grain yield was observed when maize and cowpea were sown simultaneously with the application of 80 kg N ha⁻¹ (0.99 t ha⁻¹), while the lowest yield was obtained when cowpea was sown 3 weeks after maize (0.37 t ha⁻¹), irrespective of nitrogen supply. Overall, our findings suggest that maize/cowpea intercropping with simultaneous sowing of maize can enhance the grain yield of cowpea in the Yucatan Peninsula.