Effect of VPD and potassium interactions on nutrient uptake and photosynthetic properties of tomato under high temperature
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DOI:10.7606/j.issn.1000-7601.2020.06.05
Key Words: tomato  vapor pressure difference  potassium level  nutrient absorption  photosynthetic response  CO2 response
Author NameAffiliation
ZHANG Jiayu College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China 
JIAO Xiaocong College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China 
SONG Xiaoming College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China 
DING Juping College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China 
BAI Ping College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China 
LI Jianming College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China 
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Abstract:
      Air Vapor Pressure Difference (VPD) is the main driving force for plant water transport, which affects the absorption of nutrients by crops. To investigate the absorption and photosynthetic characteristics of different VPD and potassium (K) on crop nutrient elements under high temperature is of great significance for the reasonable fertilization and environmental management of summer tomatoes. We used the tomato seedlings of Jinpeng 14-6 as test materials, and a potted plant model of nutrient solution was used to set 2 VPD treatments (HVPD, LVPD) and 3 K levels (2, 4 mmol·L-1, and 8 mmol·L-1). The effects of the interaction of VPD and K on nutrient absorption, light and CO2 response, and gas exchange parameters were studied. The results showed that, lowering VPD produced a dilutive effect on the N, P, and K contents in all organs of seedling plants, but the accumulation of N, P, and K significantly increased with increasing K levels, with total accumulation increase of N by 99.6%, 98.1%, and 44.7%, P by 57.4%, 50.4% and 51.6%, and K by 145.9%, 71.5%, and 30.6%, respectively. Plants under low VPD had larger light, CO2 concentration adaptation interval and high photosynthesis and related parameters, including photosynthetic rate Pn, stomatal conductance Gs, light saturation point LSP, apparent quantum efficiency AQY, dark respiration rate Rd, and the initial carboxylation efficiency CE, etc., and all reached the maximum at the medium K level. At the same time, transpiration rate Tr, light compensation point LCP, and photorespiration rate Rp were all significantly reduced. It is generally believed that high K levels under high VPD and medium K levels under low VPD improved tomato photosynthetic performance, N, P, and K absorption and dry matter accumulation, which can be used as indicators of high temperature fertilization and environmental management in summer.