Abstract Tea polyphenols are one of the most important ingredients in Qingzhuan tea. Usually, a chemical method is used to determine tea polyphenols content, but it was time-consuming and laborious. This paper attempted to use near infrared spectroscopy (NIRS) technology combined with three partial least squares methods to predict tea polyphenols content quickly and nondestructively. The partial least squares (PLS), synergy interval PLS (siPLS) and genetic algorithm based PLS (gaPLS) were used to establish prediction models, the performance of the final model was showed by root mean square error of prediction (RMSEP) and determination coefficient (Rp2) in prediction set. The best spectral preprocessing method was multivariate scattering correction (MSC); the RMSEP and Rp2 of PLS model were 0.145% and 0.8974, respectively; the siPLS model was established with four spectral regions (4377.6 cm-1-4751.7 cm-1, 4755.6 cm-1-5129.7 cm-1, 6262.7 cm-1-6633.9 cm-1 and 7386 cm-1-7756.3 cm-1), whose RMSEP and Rp2 were 0.0652% and 0.9235, respectively; the gaPLS model was established with 36 spectra dada points and showed the best performance (RMSEP=0.0624%, Rp2=0.9769) compared with the PLS and si-PLS models. Therefore, the application of near infrared technology combined with the gaPLS method could predict tea polyphenols content in Qingzhuan tea more accurately and rapidly.

Safeners are an important tool used to ensure the safe using of herbicide. The objective of this paper was to investigate the protective effect of four 3-dichloroacetyl oxazolidine safeners (3-dichloroacetyl-2,2-dimethyl-1,3-oxazolidine [R-28725], racemate of 3-dichloroacetyl-2,2-dimethyl-4- ethyl-1,3-oxazolidine, and its two chiral stereoisomers) in reducing the injury caused by imazethapyr. Physiological and biochemical tests were conducted under laboratory condition, by using seed treatment with safeners and soil treatment with imazethapyr, respectively. The interaction of two safeners (R-28725 and R-stereoisomer) and imazethapyr reduced the injury of maize significantly, and also increased glutathione content, activity of glutathione S-transferases, and activity of acetolactate synthase in maize. When induced by R-stereoisomer, the GSH content in root and in shoot increased 100.7% and 73.6%, respectively. When induced by R-28725, the GST activity in vivo increased threefold and the GST activity in vitro more than doubled. The kinetic parameter Vmax of GST in the maize treated with R-28725 and R-stereoisomer increased by 102.2% and 81.9%, respectively, compared with the control. The results also showed that R-28725 and R-stereoisomer induced glutathione S-transferases affinity for the substrate of conjugation reaction significantly.