Efficient use of water in four genotypes of cowpea (Vigna unguiculata L. walp) aiming to face water deficit

Cowpea (Vigna unguiculata L. walp) is grown in small areas without technology and with yields not exceeding 1,000kg ha-1. Water management is paramount to address water deficit caused by rainfall variability. A complete block experimental design was implemented with two factors and four levels each, with a split plot arrangement with four repetitions to apply irrigation sheets of 2.0, 2.8, 3.6 and 4.4 mm day-1 to the LC-019, LC-005-016, LC-014-016 and CAUPICOR 50 cowpea genotypes. The research was carried out in Monter & iacute;a, Colombia, located at 8 degrees 48' North Latitude and 75 degrees 52' West Longitude. Total dry mass and leaf area variables were assessed 55 days after emergence (DAE). At the cycle end, weight of 100 seeds and yield were determined. The largest leaf area was recorded for LC-005-016 and LC-014-016 with 3,178.23 and 2,802.23 cm2 plant-1 for 4.4 mm day-1, respectively. The highest biomass was recorded for the LC-005-16 genotype, with 127.6g plant-1 for 4.4 mm day-1. Yield of genotypes increased, when increasing irrigation sheet, being CAUPICOR 50 and LC-019 the ones with the highest yield, with 2,276.62 and 2,092 kg ha-1 for 4.4 mm day-1. Similar water consumption was found between CAUPI-COR 50 and LC-019 with Kc of 1.1 and LC-005-016 with LC-014-016 with Kc of 0.9. These Kc values allow us to know the consumptive use of each of these genotypes for any climatic zone by multiplying them by its evapotranspiration.