水肥耦合对芒果光合特性和产量及水肥利用的影响

Effect of water-fertilizer coupling on photosynthetic characteristics, fruit yield, water and fertilizer use of mango

为探明干热区芒果高效生产的水肥耦合模式。以4a生芒果树(贵妃芒)为研究对象,采用4因素3水平正交试验设计,共9个处理。试验4因素为3个生育期施肥量(花芽分化期:FⅠ、开花期:FⅡ、果实膨大期:FⅣ)和灌水水平。3个施肥水平分别为高肥(F75)、中肥(F50)和低肥(F25),3个灌溉水平分别为充分灌溉(FⅠ)、轻度亏水灌溉(DIM)和重度亏水灌溉(DIS)。分析芒果冠层结构、光合特性、产量及水肥利用效率对水肥调控的响应规律。结果表明,与充分灌溉相比,重度亏水显著减少叶面积指数、净光合速率(15:00除外)、蒸腾速率、气孔导度和羧化效率(P<0.05)。在果实膨大期施肥之后,T8处理(FⅠFⅠ50FⅡ25FⅣ75)叶面积指数和蒸腾速率最大;T6处理(DIMFⅠ75FⅡ25FⅣ50)11:00的净光合速率和羧化效率均高于其余处理;此外,大多轻度亏水灌溉下11:00的叶片瞬时水分利用效率显著大于充分灌溉(P<0.05)。在全生育期定量施肥条件下,增加芒果花芽分化期和果实膨大期肥料占比,充分灌溉能提高产量和肥料利用效率,而轻度亏水灌溉能提高灌溉水分利用效率。T8处理的产量(14 480.46 kg/hm^2)和肥料偏生产力(96.54 kg/kg)最大,T6处理的灌溉水分利用效率(6.67kg/m^3)最高。由极差分析可知综合影响产量和水肥利用的各因素依次为:灌溉水平、开花期施肥、果实膨大期施肥和花芽分化期施肥。综合评分法表明,水肥耦合的最优模式为轻度亏水灌溉、花芽分化期高肥、开花期低肥和果实膨大期中肥组合(DIMFⅠ75FⅡ25FⅣ50)。该研究结果可为干热区芒果水肥管理提供科学依据。

Mango(Mangifera indica L.) is one of the most important economic crops in dry and hot regions of southwest China. The yield is unstable due to seasonal drought, no irrigation or flood irrigation, and irrational fertilizer. Given the current situation of water and fertilizer supply as well as future scenarios, it is important to delineate strategies for improving water and fertilizer use efficiency and crop productivity. In this study, the native 4-year-old mango(Mangifera indica L., cv.‘Guifei’) was chosen as experiment material. The field experiment was conducted during main growing seasons(from January to July in 2018) in an experimental mango orchard in Yuanjiang Country, Yunnan, China. We investigated the effect of water and fertilizer regulating on canopy structure, photosynthetic characteristics, fruit yield, irrigation water use efficiency(IWUE), and fertilizer partial productivity of mango. The irrigation and fertilizer treatments were designed in orthogonal experiment(L9(34)). Four experimental factor were included the supply fertilizer at the three growth stages(flower bud differentiation stage(FⅠ), flowering stage(FⅡ) and fruit expansion stage(FⅣ)) and irrigation level. Three fertilization levels were 75 kg/hm^2(F75), 50 kg/hm^2(F50), and 25 kg/hm^2(F25), and three irrigation levels were full irrigation(FⅠ-100%ETc, ETc means crop water requirement), mild deficit irrigation(DIM-75%ETc), and severe deficit irrigation(DIS-50%ETc), respectively. The results showed that compared with FI, DIS reduced significantly LAI, net photosynthetic rate(except for 15:00), transpiration rate, stomatal conductance and carboxylation efficiency(P<0.05). After fertilizer application at fruit expansion stage, T8 treatment(FIFⅠ50FⅡ25FⅣ75) had the largest LAI and transpiration rate, and the net photosynthetic rate, stomatal conductivity and carboxylation efficiency at 11:00 of T6 treatment(DIMFⅠ75FⅡ25FⅣ50) were higher than that of other treatments. In addition, the leaf instantaneous water use efficiency(LWUE) at 11:00 of most DIM was much higher than FI(P<0.05). Under the condition of quantitative fertilization in the whole growth period, the increase of the proportion of fertilizer distribution in flower bud differentiation and fruit expansion could increase the fruit yield and the fertilizer partial productivity at FI, and could improve IWUE at DIM. T8 treatment had the largest fruit yield(14 480.46 kg/hm^2) and fertilizer partial productivity(96.54 kg/kg), and T6 treatment had the highest IWUE(6.67 kg/m^3). The order of factors affecting the fruit yield, water and fertilizer use efficiency was obtained by the range analysis as follows: irrigation level> flowering stage fertilization> fruit expansion period fertilization> flower bud differentiation stage fertilization. The comprehensive scoring method evaluation indicated that, the optimal mode of coupling between variable fertilization at different growth stages and irrigation was irrigation level of 75%ETc, fertilizer rate of flower bud differentiation stage of 75 kg/hm^2, flowering stage of 25 kg/hm^2, and fruit expansion stage of 50 kg/hm^2(DIMFⅠ75 FⅡ25FⅣ50). The study results could provide a scientific reference to water and fertilizer managements of mango in dry and hot regions.