Biochar mitigates negative effects of salt additions on two herbaceous plant species

Addition of pyrolyzed biomass ("biochar") to soils has commonly been shown to increase crop yields and alleviate plant stresses associated with drought and exposure to toxic materials. Here we investigate the ability of biochar (at two dosages: 5 and 50 t ha(-1)) to mitigate salt-induced stress, simulating road salt additions in a factorial glasshouse experiment involving the broadleaved herbaceous plants Abutilon theophrasti and Prunella vulgaris. Salt additions of 30 g m(-2) NaCl to unamended soils resulted in high mortality rates for both species. Biochar (Fagus grandifolia sawdust pyrolyzed at 378 °C), when applied at 50 t ha(-1) as a top dressing, completely alleviated salt-induced mortality in A. theophrasti and prolonged survival of P. vulgaris. Surviving A. theophrasti plants that received both 50 t ha(-1) biochar and salt addition treatments showed growth rates and physiological performance similar to plants without salt addition. Biochar treatments alone also substantially increased biomass of P. vulgaris, with a ∼50% increase relative to untreated controls at both biochar dosages. Biochar did not significantly affect photosynthetic carbon gain (Amax), water use efficiency, or chlorophyll fluorescence (Fv/Fm) in either species. Our results indicate that biochar can ameliorate salt stress effects on plants through salt sorption, suggesting novel applications of biochar to mitigate effects of salinization in agricultural, urban, and contaminated soils.

Optimisation of potassium chloride nutrition for proper growth, physiological development and bioactive component production in Prunella vulgaris L

Prunella vulgaris L. is an important medicinal plant with a variety of pharmacological activities, but limited information is available about its response to potassium chloride (KCl) supplementation. P. vulgaris seedlings were cultured in media with four different KCl levels (0, 1.00, 6.00 and 40.00 mM). Characteristics relating to the growth, foliar potassium, water and chlorophyll content, photosynthesis, transpiration, nitrogen metabolism, bioactive constituent concentrations and yield were determined after three months. The appropriate KCl concentration was 6.00 mM to result in the highest values for dry weight, shoot height, spica and root weight, spica length and number in P. vulgaris. The optimum KCl concentration resulted in a maximum net photosynthetic rate (Pn) that could be associated with the highest chlorophyll content and fully open stomata conductance. A supply of surplus KCl resulted in a higher concentration of foliar potassium and negatively correlated with the biomass. Plants that were treated with the appropriate KCl level showed a greater capacity for nitrate assimilation. The Pn was significantly and positively correlated with nitrate reductase (NR) and glutamine synthetase (GS) activities and was positively correlated with leaf-soluble protein and free amino acid (FAA) contents. Both KCl starvation (0 mM) and high KCl (40.00 mM) led to water loss through a high transpiration rate and low water absorption, respectively, and resulted in increased concentrations of ursolic acid (UA), oleanolic acid (OA) and flavonoids, with the exception of rosmarinic acid (RA). Moreover, the optimum concentration of KCl significantly increased the yields of RA, UA, OA and flavonoids. Our findings suggested that significantly higher plant biomass; chlorophyll content; Pn; stronger nitrogen anabolism; lower RA, UA, OA and flavonoid accumulation; and greater RA, UA, OA and flavonoid yields in P. vulgaris could be expected in the presence of the appropriate KCl concentration (6.00 mM).

[Research on callus induction and plantlet regeneration of Prunella vulgaris]

OBJECTIVE

To study the conditions of callus induction and plantlet regeneration of Prunella vulgaris.

METHOD

By using the orthogonal experiment design, different explants, sucrose, plant growth substances and their ratio for callus induction and differentiation were optimized.

RESULT AND CONCLUSION

The inductivity of leaves was the highest, followed by stems, but callus of the leafstalks could not be induced. The main factor of affecting the formation of callus was 6-BA. The optimal medium for callus induction was MS + 6-BA 3.0 mg x L(-1) + NAA 0.1 mg x L(-1) + 2,4-D 0.5 mg x L(-1) + sucrose 3%. The optimal medium for callus differentiation was 1/2 MS + 6-BA 3.25 mg x L(-1) + NAA 1.25 mg x L(-1) + sucrose 2%. The optimal medium for rooting was MS + IBA 1.0 mg x L(-1) + sucrose 3%.

[Effects of seed priming on drought tolerence in Prunella vulgaris]

OBJECTIVE

To explore an effective way to increase drought tolerance of Prunella vulgaris seed.

METHOD

The treatment of drought stress to P. vulgaris seeds was made by the different concentrations of PEG solutions. Primed seeds germinated under 25% PEG.

RESULT

As concentrations of PEG increasing, seed germination percentage, germination index and vitality index reduced. Primed with 20%-25% PEG, 300-500 mg x L(-1) GA3 and 1.6%-2.0% KNO3-KH2PO4 could enhance three population seeds germination index and vitality index under drought stress. Treated with NaCl, seeds germination percentage and germination index of two population increased, which came from Nanjing Zijinshan and Anhui Jinzhai, respectively, while those of seeds from Gansu Chengxian reduced.

CONCLUSION

Treated with PEG, GA3, KNO3-KH2 PO4 under proper concentration, seed vigor, seed resistance under drought stress would increase.

[Effects of seed priming on salt tolerance in Prunella vulgaris seed germination under saline conditions]

OBJECTIVE

Selecting an effective way to increase salt-resistance of Prunella vulgaris seed through seed priming technology.

METHOD

The treatment of salt stress to P. vulgaris seeds was made by the different concentrations of NaCl solutions. Primed seeds germinated under 0.8% NaCl.

RESULT

As concentrations of NaCl increasing, seed germination percentage, germination index and vitality index reduced. Primed with 15%-35% PEG, 100-500 mg x L(-1) GA3 and 0.4%-2.0% KNO3-KH2PO4 could enhance seeds germination index and vitality index under salt stress while treated with NaCl seeds germination percentage reduced.

CONCLUSION

Treated with PEG, GA3, KNO3-KH2PO4 under proper concentration, the seed vigor, seed resistance under salt stress increased.

[Effects of seed priming on vigor of Prunella vulgaris seeds]

OBJECTIVE

To select an effective way to enhance vigor of Prunella vulgaris seeds.

METHOD

Three population seeds were treated at the 20 degrees C and dark enviroment.

RESULT

Priming with 20% - 30% PEG and 200 - 400 mg x L(-1) GA3 could enhance seeds germination and vigor. Germination percentage of three population seeds treated with 0. 6% - 3.0% NaCl reduced, but they started to germinate in advance. Treated with 0.6% - 2.4% KNO3-KH2PO4, germination rate and vigor of seeds in Zijinshan and Pan' an both increased and the one in Bozhou decreased.

CONCLUSION

Vigor of P. vulgaris seed treated with PEG and GA3 under proper concentration increases, while treated with KNO3-KH2PO, and NaCl low vigor seeds germination rate reduces.