Salt Priming Protects Photosynthetic Electron Transport against Low-Temperature-Induced Damage in Wheat

Low temperature limits the photochemical efficiency of photosystems in wheat plants. To test the effect of salt priming on the photosynthetic electron transport in wheat under low temperature, the germinating seeds of a winter wheat cv. Jimai44 were primed with varying concentrations of NaCl solutions (0, 10, 30, and 50 mM NaCl, indicated by S0, S10, S30, and S50, respectively) for 6 d, and after 11 d of recovery, the seedlings were subsequently exposed to 24-h low-temperature stress (2 °C). Under low temperature, the S30 plants possessed the highest absorption flux per reaction center and higher density of reaction center per cross-section among the treatments. In addition, S30 plants had higher trapped energy flux for reducing QA and fraction of QA-reducing reaction centers and non-QB reducing center than the non-primed plants under low temperature, indicating that S30 plants could maintain the energy balance of photosystems and a relatively higher maximum quantum efficiency of photosystem II under low temperature. In addition, the low temperature-induced MDA accumulation and cell death were alleviated by salt priming in S30 plants. It was suggested that salt priming with an optimal concentration of NaCl solution (30 mM) during seed germination enhanced the photochemical efficiency of photosystems in wheat seedlings, which could be a potential approach to improve cold tolerance in wheat at an early stage.

Salt priming improves establishment of Distichlis spicata under saline conditions

Salt priming as a tool to establish Distichlis spicata (L.) Greene cv. Yensen-4a (NyPa Forage) plants into saline conditions was investigated in sand culture. Plants were pre-treated with 3 levels of salinity (0, 2, and 4 g NaCl/kg sand) for 36 days and then transplanted into 4 salinity treatments of 0, 2, 4, and 8 g NaCl/kg sand. Soil electrical conductivity (EC), Na and Cl concentrations in the sand, growth initiation, tiller formation, dry matter production, and salt excretion and uptake were measured. Plants pre-treated with 4 g NaCl/kg sand produced 6-fold more dry matter than plants pre-treated with 0 and 2 g NaCl/kg sand when transplanted into sand containing 2 g NaCl/kg. Survival and tiller formation were also higher with plants that had been pre-treated with 4 g NaCl/kg sand compared with plants pre-treated with 0 and 2 g NaCl/kg, when transplanted into 2 and 4 g NaCl/kg sand. The results suggest that salt priming improves establishment of Distichlis spicata when transplanted into low to moderate salinity conditions.

620 Enhancing Germination of Purple Coneflower (Echinacea angustifolia) Using Stratification, Salt Priming, and Biostimulants

Using herbs for medicinal purposes, ornamentals, and landscape plantings has increased significantly. Propagating from seeds is considered the most-efficient method of producing medicinal plants for commercial production. Among the herb seeds the purple coneflower (Echinacea angustifolia) was found difficult to germinate. Laboratory studies were conducted to: 1) determine optimum temperature from a temperature range 15 to 30 °C for seed germination; 2) determine effects of 5 10, 20, and 30 days of stratification at 5 and 10 °C in darkness on germination; and 3) determine effects of priming in the dark for 1, 3, 6, and 9 days with 0.1 M KNO3 and biostimulants at optimum temperature to enhance early emergence and final germination. Germination was enhanced from 45% in untreated seeds to 81% in seeds treated with either 50 ppm GA4/7 or 100 ppm ethephon at 24 °C. Final germination was 81% under daylight conditions when seeds were stratified in dark at 10 °C for 30 days over nonstratified seeds (13%). Priming seeds in 0.1 M KNO3 for 3 days significantly enhanced early germination to 70% with 100 and 150 ppm ethephon and final percent germination of 88% with either 100 ppm ethephon or 150 ppm GA4/7, while untreated control seeds resulted in 31% for same period of priming.

PRIMING PETUNIA

NaCl, KNO3 (0.3, 0.4, 0.5M), KH2P O4 (0.4, 0.5, 0.6M), and PEG 8000 (320 to 370 g/L with the increment of 10g/L) were used for priming Petunia `Ultra White' seeds for three to six days. Seeds were germinated in a growth chamber at 25C. Germination was recorded for seven days and the number of acceptable seedlings (seedlings with open cotyledon and normal root) was counted on the day seven. KH2P O4 at 0.6M was the best salt treatment. Rate of germination was improved by salt priming but the number of acceptable seedlings was lower than the control. Addition of GA (5 ppm) to the salt treatment was not effective. More abnormal seedlings were observed when seeds were primed in aerated salt solutions than when primed in petri dishes. Aerated PEG at 325 g/L for three days and 365 g/L for six days gave the best results. Priming in PEG improved percent of germination, rate of germination, and number of acceptable seedling as compared to control. Primed seeds lost some of the advantages of priming during 24hr air drying (22C), however quality was maintained when dried at 10C. Drying primed seed in 80% R.H. was not effective.