Effect of potassium fulvic acid on photosynthetic characteristics of leaf and fruit quality of Siraitia grosvenorii
To explore the effect of potassium fulvic acid on leaf photosynthetic characteristics and fruit quality of Siraitia grosvenorii,and provide reference for high-quality and high-yield cultivation of S.grosvenorii in Wuling Mountain Region,the tissue culture seedlings of'Qingpi Guo'S.grosvenorii was used as the experi-mental material planted with plant space of 2.0 m and row space of 2.5 m.Four treatments of potassium fulvic acid were set up,including the amount of potassium fulvic acid of 60 kg/hm2,90 kg/hm2,120 kg/hm2 and 150 kg/hm2,with no application of potassium fulvic acid as control.The contents of photosynthetic pigments(chlorophyll a,chlorophyll b and carotenoids),diurnal changes of net photosynthetic rate,light response pa-rameters,chlorophyll fluorescence kinetic parameters of leaves,and the fruit size and content of mogroside V of fruits were measured and compared when five to seven leaves appeared on the secondary lateral bine.The results showed that potassium fulvic acid could increase the content of photosynthetic pigment in leaves and the leaf light saturation point,and enhance the leaf light quantum transfer ability.The treatment of 120 kg/hm2 potassium fulvic acid showed the highest photosynthetic indexes,with larger fruit vertical and horizontal diam-eter,higher dry weight of single fruit and mogroside V content,which increased by 11.77%,9.6%,11.95%and 18.98%,respectively,compared with the control.Potassium fulvic acid could improve the photosynthetic capacity of S.grosvenorii leaves,promote fruit enlargement and accumulation of mogroside V.The appropri-ate application rate was 120 kg/hm2.
Siraitia grosvenorii(Swingle)potassium fulvic acidphotosynthetic characteristicschlorophyll fluorescencedry weight of single fruitmogroside V