Diethyl Aminoethyl Hexanoate Priming Ameliorates Seed Germination via Involvement in Hormonal Changes, Osmotic Adjustment, and Dehydrins Accumulation in White Clover Under Drought Stress

Drought is a serious outcome of climate change reducing the productivity of forage species under arid and semi-arid conditions worldwide. Diethyl aminoethyl hexanoate (DA-6), a novel plant growth regulator, has proven to be involved in the amelioration of critical physiological functions in many agricultural crops under various abiotic stresses, but the role of the DA-6 in improving seed germination has never been investigated under drought stress. The present study was carried out to elucidate the impact of the DA-6 priming on seeds germination of white clover under drought stress. Results showed that seed priming with the DA-6 significantly mitigated the drought-induced reduction in germination percentage, germination vigor, germination index, seed vigor index, root length, shoot length, and fresh weight after 7 days of seed germination. The DA-6 significantly increased the endogenous indole-3-acetic acid, gibberellin, and cytokinin content with marked reduction in abscisic acid content in seedlings under drought stress. In addition, the DA-6 significantly accelerated starch catabolism by enhancing the activities of hydrolases contributing toward enhanced soluble sugars, proline content and ameliorated the antioxidant defense system to enhance the ability of reactive oxygen species scavenging under drought stress. Furthermore, exogenous DA-6 application significantly increased dehydrins accumulation and upregulated transcript levels of genes encoding dehydrins (SK2, Y2SK, or DHNb) during seeds germination under water deficient condition. These findings suggested that the DA-6 mediated seeds germination and drought tolerance associated with changes in endogenous phytohormones resulting in increased starch degradation, osmotic adjustment, antioxidants activity, and dehydrins accumulation during seed germination under water deficient condition.

Plant Growth Regulators Increase Soybean Yields by Delaying Leaf Senescence in Maize (Zea mays L.)-Soybean [Glycine max (L.) Merr] Relay Strip Intercropping System

Background: The shading caused by maize inhibited the growth of soybean, reduced the yield of soybean under maize-soybean relay strip intercropping system. To investigate whether foliar spraying different types of plant growth regulators could improve the growth and yield of intercropped soybean.Methods: A field experiment was conducted in 2018 to evaluate the effect of foliar spraying 6BA (6-benzylaminopurine), S3307 (uniconazole) and DTA-6 (diethyl aminoethyl hexanoate), at the soybean beginning flowering stage, on the growth and yield of three soybean varieties (i.e., Nandou 25 (ND25), Gongqiu 8 (GQ8) and Guixia 3 (GX3)).Result: The leaf area index of three soybean varieties were highest in DTA-6 at 35 days after spraying (DAS) and no significant difference (p less than 0.05) were observed among three plant growth regulators. The chlorophyll a and chlorophyll b content under 6BA and DTA-6 treatments were significantly higher than CK and S3307 at 35 DAS. The activities of antioxidant enzymes (i.e., SOD (Superoxide dismutase) and CAT (Catalase) and antioxidant substances (i.e., GSH (Glutathione) were increased after spraying 6BA, S3307 and DTA-6 in three soybean varieties at 35 DAS. Independent soybean varieties, foliar spraying 6BA, S3307 and DTA-6 increased the soybean yield, pods per plant, 100-grains weight and grain per plant and the effect of DTA-6 (60 mg l -1) treatment were best than others.

Induction of Adventitious buds from stem explants in Aoectochilus formosanus

In order to explore the optimal culture conditions for adventitious bud regeneration of stem explants in Aoectochilus formosanus, the stem segments from the sterile seedlings were used as explants, and different concentrations of diethyl aminoethyl hexanoate (DA-6), kinetin (KT), Cu2+ and glutamine (Gln) were separately added into MS medium containing 6-benzylaminopurine (6-BA) and naphthaleneacetic acid (NAA), and the induction rate and the induction multiple of adventitious buds were recorded and analyzed. The results showed that the regeneration of adventitious buds could be promoted, when 2 mg/L DA-6, 0.4 mg/L KT and 15 mg/L Gln were added in mediums. However, the effect of Cu2+ on the regeneration of adventitious buds in A. formosanus was enhanced by low concentration and suppressed by high concentration, and the best concentration of Cu2+ was 5 mg/L.