Effect Of Biogas Slurry Foliar Spraying On Plant Growth And Fruit Production Of Pepino (Solanum Muricatum) Under Different Fertilization Conditions

Pepino(Solanum muricatum Aiton)is a perennial herb of the Solanum genus native to the South America.As a highly nutritious fruit,the contents of protein,amino acid,vitamins and trace elements in pepino fruits are higher than those in most other fruits,and the flesh is fragrant,crisp and juicy,and there is no nucleus in the belly,with unique flavor.At present,it is widely cultivated in the solar greenhouse in the Hexi Corridor region of Gansu Province as a special economic crop.However,the domesticated planting history of pepino in our country and even in the world is very short.There are few studies on the nutritional characteristics of pepino plants,and fertilization bases mainly on experience in the production.Further improvement of the fertilization method lacks the necessary theoretical support.In this study,the main cultivar 'Aska' was used as a material to investigate the effects of foliar spraying of biogas slurry on plant growth and fruit production of pepino in the solar greenhouse in fruit developmental stages with or without chemical fertilizers.To provide scientific basis for rational fertilization of pepino.The main results are as follows:(1)Foliar spraying of biogas slurry significantly promoted the growth of pepino plants.The differences in plant heights and stem diameters between treatments increased gradually with the growth period,but there was no significant difference in plant height among three growth stages.Under fertilization condition,the plant height and stem diameter of pepino increased by an average of 12.0% and 13.0%,respectively after spraying the biogas slurry,and increased by 9.0% and 11.0% on average with no chemical fertilizers.The plant heights sprayed with biogas slurry of 100 and 200 times were significantly higher than those of the control,and the plant height sprayed with 100 times biogas slurry was significantly higher than those with 200 and 400 times of biogas slurry,but no significant difference was found between biogas slurry spraying of 400 times and the control.(2)From the flowering to the fruit ripening stage,pepino leaf area gradually increased,the specific leaf weight showed a trend of first increase and then decrease.Under fertilization,the average growth rate of the leaf area after biogas slurry spraying(17.4%)was higher than those with non-fertilizers(14.9%),and the increase rate of leaf area after biogas slurry spraying of 100 times(31.3%)was significantly greater than those of 200(16.5%)and 400 times(4.5%);in the same way that increase rate of specific leaf weights after biogas slurry spraying of 100 times(21.48%)was significantly greater than those of 200(11.65%)and 400 times(5.14%),the average increase rate in specific leaf weight(12.4%)of biogas slurry spraying under fertilization was greater than that with no fertilizers(9.9%).(3)Foliar spraying of biogas slurry significantly increased the photosynthetic pigment contents of pepino leaves,with the average increase rates of 13.5% and 12.0% respectively under fertilization and non-fertilization.And the increase rate treated with 100 times biogas slurry was significantly greater than those with 200 and 400 times.From flowering to fruit ripening stage,the gas exchange parameters of the pepino leaves showed the trend of increasing first and then decreasing and reached the peak at fruit expanding period.The leaf gas exchange parameters after spraying 100 times of biogas slurry under fertilizing condition and no fertilizing increased by 43.5% and 47.7%(Pn),30.9% and 33.0%(Tr),47.9% and 78.1%(Gs),9.5%,and 4.2%(WUE)respectively.(4)Foliar spraying of biogas slurry significantly increased the yield and quality of pepino fruits.Under the fertilizing condition,the single fruit weight,the yield and its increase rate were significantly higher than those with no fertilizers.After spraying 100 times of biogas slurry,the yield increase rate(88.90% for fertilizer and 49.22% for not fertilizers)was significantly higher than that for the control.The fruit vertical and horizontal,flesh thickness and hardness as well as soluble solids content increased with the biogas slurry concentration.The vertical and horizontal growth rates were increased by spraying 100 times the biogas slurry(25.61% for fertilizing,17.48% for no fertilizing)and flesh thickness.The increase(13.19% for fertilizing,11.73% for no fertilizing),increase in hardness(28.43% for fertilizing,15.1% for no fertilizing),and increase in soluble matter content(38.89% for fertilizing,32.20% for no fertilizing)were significantly higher than the control.