Effects Of Fertigation Modes On The Growth Characteristics Of Mango Seedling And Soil Microecological Environment

Mango?Mangifera indica L.?is one of the five famous fruits in the world and enjoys the reputation of“the King of Tropics Fruits”with wide planting area and remarkable economic benefits.However,the growth of mango is often affected by seasonal drought and soil barrenness.Scientific management of water and fertilizer is of great significance to achieve green and efficient production of mango.The aim of this study was to investigate the suitable fertigation mode?water and fertilizer integration?for high-quality cultivation of mango seedlings.A plot experiment was carried out with two-year-old mango seedlings as experimental materials.In the experiment,three fertigation patterns?SI:micro-sprinkler fertigation;DI:drip fertigation;MI:moistube fertigation?and four fertilization levels(F₀:no fertilizer at 0 g·plant^-1;F_L:low fertilizer at 9.32 g·plant^-1;F_M:medium fertilizer at 18.64 g·plant^-1;F_H:high fertilizer at 27.96 g·plant^-1)were designed to study the effects of fertilization level on soil water and nutrients distribution,soil microecological environment and physiological growth characteristics of mango seedlings under different fertigation patterns.The main results of this study as follows:?1?Fertigation pattern had significant effects on the distribution of soil water and nutrients,and fertilization level only had effects on the distribution of soil nutrients.Under different fertigation patterns,average accumulative content of soil water and nutrients and distribution uniformity coefficients of water and nutrients were in order of:MI>DI>SI.Accumulative content of soil nutrients significantly increased,while distribution uniformity coefficient decreased with the increase of fertilization level.?2?Compared with SI treatment,DI and MI treatment increased soil respiration rate by26.83%-49.54%,soil enzymes?catalase,urease and acid phosphatase?activities by 14.98%-45.80%and soil microbial?bacteria,fungi and actinomycetes?amounts by 11.46%-42.45%,respectively,of which MI treatment had the best effect.Compared with F₀ treatment,increasing fertilization level improved soil respiration rate by 12.93%-41.38%,soil enzymes activities by 20.66%-113.65%and soil microbial amounts by 21.67%-93.49%,respectively.Among them,soil respiration rate,catalase activity,urease activity and microbial number all were the highest in F_M treatment,but acid phosphatase activity was highest in F_H treatment.?3?Compared with SI treatment,DI and MI treatment significantly increased net photosynthetic rate,stomatal conductance,chlorophyll content,hydraulic conductivity of mango seedlings,but not obviously increased or decreased transpiration rate and reduced intercellular CO₂ concentration.Net photosynthetic rate,stomatal conductance,chlorophyll content,hydraulic conductivity first increased and then decreased,while transpiration rate and intercellular CO₂concentration first decreased and then increased with the increase of fertilization level.Compared with SIF₀ treatment,MIF_H treatment significantly increased leaf water use efficiency.?4?Compared with SI treatment,DI and MI treatment significantly increased plant height,stem diameter,crown width,total dry mass accumulation,root total length and leaf area of mango seedlings,of which MI treatment had the best promotion effect.Compared with F₀ treatment,increasing fertilization level increased plant height by 12.87%-24.24%,stem diameter by 6.79%-8.22%,crown width by 11.79%-23.49%,total dry mass accumulation by 22.53%-49.62%,root total length by 8.36%-21.80%and leaf area by 22.53%-49.61%,respectively.Seedling index,irrigation water use efficiency and fertilizer agronomic efficiency all were the highest and fertilizer partial factor productivity was moderate in MIF_M treatment.The relationship between plant height,stem diameter,number of leaf,crown width of mango seedlings and planting days conformed to Logistic model under different fertigation modes.?5?The comprehensive evaluation method based on subordinate function and factor analysis showed that MIF_M treatment had the best soil microecological environment quality and growth quality of mango seedlings.In conclusion,MIF_M treatment was the most beneficial to the growth of mango seedlings,which could significantly enhanced photosynthesis and hydraulic conductivity,increase seedling index and water and fertilizer use efficiency,and improve soil microecological environment.Therefore,considering the comprehensive benefits of high-quality cultivation and efficient use of water and fertilizer,it was suggested that suitable fertigation mode for mango seedlings was moistube fertigation with medium fertilizer(18.64 g·plant^-1).