Agro-physiological characteristics of lettuce (Lactuca sativa L.) cultivars as influenced by irrigation and mulching in a semi-arid region of Nigeria

Abstract

Series of experiments were conducted to assess the response of agro physiological characters of three lettuce (Lactuca sativa L.) cultivars under different irrigation water application depths and mulch in a semi-arid ecology of Northern Nigeria. The experiments were conducted during three seasons of 2015/2016, 2016/2017and 2017/2018 irrigation seasons at Kadawa Irrigation Research Station farm (IRS) of the Institute for Agricultural Research, Samaru, Nigeria. The experimental design was split plot and consisted of three irrigation levels (50, 75 and 100% of weekly reference evapotranspiration (WRET), two levels of mulch (no-mulch and mulch) and three lettuce cultivars (Great Lake, Slaai and Baby Leaf Mix). Irrigation levels and cultivars were assigned to main plots while mulch level as sub-plots. Treatments were factorial combined and replicated three times. Water applied before and after irrigation was monitored throughout the seasons. The study revealed that reducing irrigation level to 50% of WRET with or without mulch significantly (P<0.05) lowered leaf area index, dry weight per plant (g), total dry matter in kg ha-1, crop growth rate, relative growth rate, net assimilation rate and irrigation water use efficiency (IWUE). Reducing water deficit to 50% WRET reduced TDM to the turn 37.3, 37.5 and 34.2% in 2015/2016, 2016/2017 and 2017/2018 respectively. Results also revealed that mulching significantly resulted in higher agro-physiological characters. Based on the results obtained in this study, it can be concluded that the use of cultivar Slaai with irrigation at 75% WRET had resulted in good agro-physiological characters of lettuce in Kadawa, Since there were only minor significant differences between yields of lettuce obtained from 75 and 100% irrigation levels, 75 emerges as a more suitable practice and might be recommended to tolerate the negative effects of excess water application to the ecology and for a better water economy especially in semi-arid regions of the world.