Improving coffee yield and quality by full irrigation under moderate shade cultivation of banana tree in dry-hot region

Abstract: The yield and quality of Coffea arabica cannot be guaranteed due to irrational irrigation and light management in dry-hot region of southwest China. In order to evaluate the effects of deficit irrigation on yield and quality of Coffea arabica under the shade of banana trees in dry-hot region, the local Coffea arabica (5 years) was chosen for test material. In the field experiment, 3 levels of irrigation, i.e., full irrigation (FI, which was determined by the monthly water demand data of Coffea arabica and precipitation in dry-hot region), light deficit irrigation (DIL: 75%FI) and severe deficit irrigation (DIS: 50%FI), and 4 modes of shade cultivation, i.e., no shade cultivation (S0: monoculture Coffea arabica, i.e., natural light intensity), light shade cultivation (SL: intercropping with 4 lines of Coffea arabica and 1 line of banana), moderate shade cultivation (SM: intercropping with 3 lines of Coffea arabica and 1 line of banana) and severe shade cultivation (SS: intercropping with 2 lines of Coffea arabica and 1 line of banana) were designed. Principal component analysis and TOPSIS method were used to evaluate total sugar, protein, fat, caffeine, chlorogenic acid, crude fiber and water extracts content of Coffea arabica comprehensively. The results showed that the dry bean yield of Coffea arabica was significantly different under different shade cultivation modes and irrigation levels (P<0.05), and there were the highest dry bean yield (5 854.34 kg/hm2) and the highest dry mass of 100-bean of Coffea arabica in the FISM treatment. But FISM was not significantly different with the FISS treatment (P>0.05)in the volume and fresh mass of 100-bean of Coffea arabica. The effects of irrigation level on total sugar content of Coffea arabica were not significant (P>0.05), and that of interaction between irrigation level and shade cultivation mode on fat and crude fibre content were also not significant (P>0.05). However, the effects of their interaction on total sugar, protein, caffeine, chlorogenic acid and water extract content of Coffea arabica were extremely significant (P<0.01). There were higher content of total sugar, protein, fat, chlorogenic acid and water extracts content of Coffea arabica of FISM treatment, while lower content of caffeine and crude fiber. Pearson correlation analysis showed that there were extremely significant positive correlation between protein, fat, chlorogenic acid and water extracts content of Coffea arabica, while significant negative correlation between crude fiber and total sugar, protein, fat, chlorogenic acid and water extracts content of Coffea arabica, respectively. Based on both principal component analysis and TOPSIS method, the best comprehensive quality of Coffea arabica was FISS treatment, the next was FISM treatment, and the poorest comprehensive quality was DISS0 treatment. Compared with the FIS0 treatment, total sugar, protein, chlorogenic acid, water extracts content and dry bean yield of FISM treatment increased by 6.11%, 10.79%, 40.58%, 9.95% and 14.32%, respectively, while protein, chlorogenic acid and water extracts content of FISS treatment increased by 19.88%, 43.10% and 11.94%, respectively, dry bean yield decreased by 15.69%. Considering the comprehensive benefit of high production and superior quality, the suitable combination of irrigation treatment and banana shade cultivation mode for Coffea arabica was full irrigation under moderate shade cultivation (FISM). To summarize, the results of the study could provide guidance for irrigation and light management of Coffea arabica in dry-hot region of southwest China.