Response of water and nitrogen coupling to zinnia growth in arid areas

In order to evaluate the effect of water and nitrogen coupling on the growth of zinnia in arid areas, this study took the tall zinnia of the "Pink Dreamland" series as the research object, and used the integrated technology of drip irrigation and water and fertilizer under film to fertilize and irrigate, and a total of 3 water regulation levels and 3 nitrogen application levels were set up, among which the water regulation levels were W₁ (75%~85% field water holding capacity FC), W₂ (65%~75%FC) and W₃ (55%~65%FC). The nitrogen fertilization levels were N₁, (90 kg·ha-1), N2 (150 kg·ha-1) and N3 (210 kg·ha-1). Based on three different irrigation levels and nitrogen application, 9 water nitrogen control treatments and one control treatment (CK) based on full irrigation (W3) and local nitrogen application (270 kg·ha-1), with a total of 10 water nitrogen combination treatments. The results showed that the SLA, Ph, Sd, Pn and Tr of Zinnia zinnia first increased and then decreased under low nitrogen conditions and showed a wave-like undulating trend of first increasing and then decreasing under medium and high nitrogen conditions. Compared with the other treatments and CK, W₂N2 significantly increased the content of SLA, Ph, Sd, Pn, Tr and soluble protein by 9.41%~43.08%, 6.87%~14.98%, 9.53~17.42, 6.20%~57.27, 1.83%~16.37 and 9.85~21.11, respectively. Therefore, the above trends indicate that the appropriate water-nitrogen ratio can promote the photosynthesis of Zinnia, increase the accumulation of nutrients in Zinnia, and increase its resistance to drought environment.