关键词: 农业废弃物, 复合基质, 利用次数, 西瓜, 光合特性, 品质

Abstract: In order to explore the effects of different agricultural waste compound substrates and their utilization times on the photosynthetic characteristics, yield and quality of watermelon, two formulated substrates were prepared by utilizing corn straw compost,Pleurotus eryngii residue compost,peat,perlite and vermiculite according to different volume ratios:T1 (V_{corn straw compost}∶V_{Pleurotus eryngii residue compost}∶V_peat∶V_perlite∶V_vermiculite=3∶1∶2∶3∶1),T2 (V_{corn straw compost}∶V_{Pleurotus eryngii residue compost}∶V_peat∶V_perlite∶V_vermiculite=3∶0∶3∶3∶1),with T3 (V_peat∶V_perlite∶ V_vermiculite= 6∶3∶1) as CK.For two consecutive years, their effects on the photosynthetic characteristics,products and quality of watermelon plants were determined and analyzed,and the substrate formula suitable for the growth of watermelon and its optimal utilization times were screened.The results showed that the bulk density,pH value and EC value of compound substrates were increased,and the total porosity and water-holding porosity were reduced when part of peat was replaced with agricultural waste.The pH value and EC value of T1 and T2 treatments were significantly higher than CK,while the total porosity and water-holding porosity of T1 were significantly lower than T2 and CK(P<0.01).The net photosynthetic rate(Pn) of T2 treatment was significantly higher than T1 treatment (P<0.01),and was significantly higher than CK (P<0.05).The transpiration rate (Tr) of T1 and T2 treatments were decreased significantly compared with CK (P<0.05) when the substrates were used once.The change trends of Tr in T1 and T2 treatments were inconsistent,but there was no significant difference with CK when the substrates were used twice. Stomatal conductance (Gs) of T1 treatments was lower than CK. Tr and intercellular CO₂ concentration (Ci) of watermelon plants were extremely significantly affected by the substrate utilization times (P<0.01).Different compound substrates of agricultural wastes could increase the singlemelon weight and yield of watermelon,and T2 treatment was significantly higher than T1 treatment (P<0.05),but there was no significant difference between T1 treatment and CK.The longitudinal diameter,central soluble solid content,marginal soluble solid content,soluble sugar,vitamin C and nitrate content of T1 and T2 treatments were significantly higher than CK(P<0.05),and the contents of soluble protein and organic acid were lower than CK when the substrates were used once. The fruit morphology and nutrient content of watermelon with different treatments had different changes,and the effects of T1 treatment were better than T2 treatment when the substrates were used twice. Except the pericarp thickness,the fruit morphology and nutrient content of watermelon were significantly affected by utilization times of different agricultural waste compound substrates(P<0.01).For the same substrate,Pn,Tr,Ci,single fruit weight and yield of watermelon when the substrate was used once were better than twice.By comprehensive evaluation of watermelon indicators,T2 treatment used once was better.

Key words: Agricultural waste, Compound substrate, Utilization time, Watermelon, Photosynthetic characteristics, Quality