Studies On The Photosynthetic Characteristics Of Different Strawberry Cultivars

Photosynthesis is the unique physiological function of plant, to study the photosynthetic characteristics of fruit trees is of great significance. Strawberry is a kind of small berry with high nutritional value, many scholars have done some research, including cultivation technology, mineral nutrition, species characteristics and so on, but different varieties of strawberry, different shading treatments of less, especially different section stolons seedling photosynthetic characteristics research has not been reported.Under the natural growth condition and shading treatments, three strawberry cultivars as the research object for the subject. We measured the net photosynthesis, stomata conductance and other photosynthetic parameters, photosynthetic pigment content、leaf physiological indexes and other physiological indexes. We analyzed photosynthetic characteristics of three varieties. The results were as follows:(1)Princess’ Pn diurnal variation curve showed bimodal type in July and August, and a single peak curve in June and September. Sweet Charlie and Beauty only showed a single peak curve in September. Gs diurnal variation curves of the same variety in different months were associated with the corresponding month Pn variation. Pn seasonal variation of three varieties showed a bimodal curve.(2)Pn-PAR and Pn-CO2 response curves of three varieties both showed the hyperbola. Pn of three varieties had the same trend with the temperature, which fitting a parabola with downward opening.(3)Three varieties’ Pn with the increase of the leaf ages showed increased first and then decreased, Pn reached a higher level in the stage of 25-30 d leaf ages. Specific leaf weight was at a higher level in the stage of 30-50 d leaf ages. Leaf relative water content and chlorophyll fluorescence parameters of leaf growth changed little with age and the difference between varieties was not significant.(4)Different node stolon seedling Pn had significant difference and three varieties’ Pn size were Ⅰ1>Ⅱ1>Ⅰ2>Ⅱ2 with section 1 position seedlings Pn of Princess was the largest and section 2 seedlings Pn of Beauty was the largest, as so the specific leaf we ight. The sections′ leaf relative water content both were located in more than 80%. Leaf tissue structure parameters and fluorescence parameters. of different node seedlings in section 1 the maxi mum.(5)Compared with the controls, by 75% shading treatment, Pn diurnal variation curves of Princess and Sweet Charlie both became a single peak. Pn diurnal variation curves of Beauty both had a single peak in different shading treatments. Pn-PAR response curves and Pn-CO2 response curves of three varieties both showed a hyperbola in different shading treatments. 50% shading treatment with the different degree reduced the AQY, LCP, CCP and improved CCP, CSP of strawberry. Three varieties’ photosynthetic pigment content and leaf tissue structure parameters changed in different shading treatments, but the difference was not significant. In addition, the 50% shading treatment have improved the parameters’ value of Fv/Fm、Fv/Fo、Fv′/Fm′、ΦPSⅡ.