Incentive effect of tax preferences towards the technological innovation of enterprises--Based on China's GEM listed companies.

The long R&D process, the high risk, and the externalities of technological innovation are challenges that enterprises have to meet when making decisions on R&D investment. Governments share this risk with enterprises through preferential tax policies. We summarized China's preferential tax policies related to enterprises and R&D innovation, and used panel data of listed enterprises from 2013 to 2018 in the Growth Enterprises Market (GEM) of the Shenzhen Stock Exchange to explore the incentive effects of current tax policies on the R&D innovation of enterprises. Through empirical analysis, we found that tax incentives significantly motivate R&D innovation input and promote output. In addition, we found that the income tax incentives are greater than that of the circulation tax, since the profitability of enterprise has a positive correlation with R&D investment. Meanwhile, the size of the enterprise is negatively correlated with the intensity of R&D investment.

Effects of soil water and nitrogen availability on photosynthesis and water use efficiency of Robinia pseudoacacia seedlings.

The efficient use of water and nitrogen (N) to promote growth and increase yield of fruit trees and crops is well studied. However, little is known about their effects on woody plants growing in arid and semiarid areas with limited water and N availability. To examine the effects of water and N supply on early growth and water use efficiency (WUE) of trees on dry soils, one-year-old seedlings of Robinia pseudoacacia were exposed to three soil water contents (non-limiting, medium drought, and severe drought) as well as to low and high N levels, for four months. Photosynthetic parameters, leaf instantaneous WUE (WUEi) and whole tree WUE (WUEb) were determined. Results showed that, independent of N levels, increasing soil water content enhanced the tree transpiration rate (Tr), stomatal conductance (Gs), intercellular CO2 concentration (Ci), maximum net assimilation rate (Amax), apparent quantum yield (AQY), the range of photosynthetically active radiation (PAR) due to both reduced light compensation point and enhanced light saturation point, and dark respiration rate (Rd), resulting in a higher net photosynthetic rate (Pn) and a significantly increased whole tree biomass. Consequently, WUEi and WUEb were reduced at low N, whereas WUEi was enhanced at high N levels. Irrespective of soil water availability, N supply enhanced Pn in association with an increase of Gs and Ci and a decrease of the stomatal limitation value (Ls), while Tr remained unchanged. Biomass and WUEi increased under non-limiting water conditions and medium drought, as well as WUEb under all water conditions; but under severe drought, WUEi and biomass were not affected by N application. In conclusion, increasing soil water availability improves photosynthetic capacity and biomass accumulation under low and high N levels, but its effects on WUE vary with soil N levels. N supply increased Pn and WUE, but under severe drought, N supply did not enhance WUEi and biomass.