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In order to find out the change rule of SPAD value in lettuce leaves and the rapid, non-destructive and more accurate detection method of chlorophyll content in lettuce leaves under intercropping mode, the effect of intercropping on SPAD value in lettuce leaves was studied and the correlation model between chlorophyll content and SPAD value was established. The results show that the SPAD value of lettuce leaves increases at first and then decreases slowly with the development of the days of aerosol culture, and intercropping has obvious advantage in the middle and late stages of aerosol culture. At the same time, the results show that the regression equations of chlorophyll a, chlorophyll b and total chlorophyll content with SPAD value are best fitted by power equation, exponential equation and power equation respectively, and the coefficients of determination are 0.8302,0.6719 and 0.8503 respectively. The models are verified. It is found that the predicted value and the measured value of chlorophyll a, chlorophyll b and total chlorophyll content have a good correlation, and there is no significant difference, which shows that the regression models have a good prediction effect on chlorophyll content. The results provide a theoretical basis for the effect of intercropping on SPAD value of lettuce leaves and provide a reference method for rapid, nondestructive and more accurate detection of chlorophyll content in lettuce leaves.

Objective: To analyze the psychometric performance of Prosocial Tendencies Measure (PTM) for undergraduates in Guangdong province. Methods: Stratified random sampling method was used to select 1109 undergraduates from 10 colleges in Guangdong province.PTM was used to investigate them. Cronbach's α coefficient and split-half reliability were used to analyze the internal consistency of the questionnaire.Convergent validity, discriminant validity and factor analysis were used to evaluate its structural validity. Celling and floor effect were used to analyze its sensitivity. Results: Cronbach's α coefficient of the total questionniar was 0.94 and cronbach's α coefficient of 6 dimensions were 0.82~0.87, which met with the requirements of the group comparison. Spearman - Brown split-half coefficient of the total questionniar was 0.95, and the split half reliability of 6 dimensions were 0.83~0.88. The calibration success rate of convergent validity and discriminant validity of the 6 dimensions were all 100%. One component obtained from 23 items which cumulative variance contribution rate was 82.31%. The total score and scores of 6 dimensions were all positive skew distribution, with floor effect in 6 dimensions. Conclusions: The psychometric properties of PTM for undergraduates in Guangdong was valid and reliable.