Chlorocholine chloride application effects on physiological responses for late season potato (Solanum tuberosum L.) under soil well-irrigated and drought-stressed conditions

The potted potatoes were grown in a greenhouse. During early tuber bulking stage, plants were exposed to full irrigation (FI), FI and chlorocholine chloride (FI+CCC), deficit irrigation (DI), and (DI+CCC) treatments for 18 days. The physiological responses relating to stomata and senescence parameters for late season potato were investigated. The results showed that the parameters of light response curve in FI+CCC and DI+CCC treated leaves on 18 days after treatment (DAT) were significantly improved those of in FI and DI controls, respectively. The net photosynthetic rate (A), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr) in FI+CCC and DI+CCC-treated leaves for late season potato were superior to those of FI and DI controls, respectively. Analysis of the pooled data on 18 DAT showed that Gs was logarithmically correlated with A; photosynthetic water use efficiency (PWUE), viz. A/Gs, increased linearly with decreasing Gs. Spraying 2.0 g l(-1) CCC resulted in an 35.0% and 124.0% increase in the content of CTK/ABA in FI and DI in potato leaves, respectively. The leaf water potential (Psi l), root water potential (Psi r) and relative water content (RWC) in FI+CCC and DI+CCC were significantly improved compared to those of FI and DI controls, respectively. Compared with FI and DI, FI+CCC and DI+CCC treatments saved 15.9% and 11.5% water and increased crop water use efficiency (WUE) by 34.3% and 27.9% during the experimental period, respectively. The relative electrical conductivity and the content of malondialdehyde (MDA) in FI+CCC and DI+CCC were less than those of FI and DI controls, respectively. The root vitality in FI+CCC, DI+CCC treatments were 39.5% and 54.4% higher than those of FI and DI treatments, respectively. Collectively, the results of this research identify that optimized application of CCC resulted in significant improvement in PWUE and WUE for late season potato under soil well-irrigated and drought stressed condition.