Drought stress is a major factor‐limiting grass growth. The production of reactive oxygen species (ROS) increases under stress conditions and causes cell oxidative damage. This study investigated the effect of sodium nitroprusside [a nitric oxide (NO) donor] treatment on drought stress in two turfgrass species, creeping bentgrass and tall fescue. Physiological characteristics such as relative water content (RWC), ion leakage, chlorophyll and proline content, and activity of superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) were evaluated after 40 d drought stress and in the recovery stage. Results showed that nitric oxide (NO) treatment, especially 150 μm, could maintain significantly higher RWC and reduce ion leakage under drought stress conditions in both species. Furthermore, both turfgrass species showed higher chlorophyll and proline content after drought stress period when sprayed with NO, while chlorophyll and proline content of control plants declined. Drought stress significantly reduced SOD and APX activity, while NO treatment induced higher SOD and APX activity under drought conditions. After recovery, leaf RWC returned to the control level; however, NO‐sprayed plants showed higher RWC compared to controls. Both turfgrass species exhibited lower chlorophyll content at the recovery stage when exposed to severe drought stress, and NO application increased chlorophyll content compared to controls. No significant differences were found between NO treatment and control plants for proline and SOD activity, but APX activity of NO‐sprayed plants was higher than in the control plants. These results suggest that foliar application of NO may alleviate drought stress in turfgrass by maintaining membrane stability and inducing antioxidant enzyme activity.

No abstract

No abstract

Alstroemeria with beautiful and long shelf life of cut flower is one of the most important ornamental plants. This plant could propagate by splitting of the in vivo produced rhizomes but the propagation rate is rather low. In the present study, regeneration ability of plantlets was compared using in vitro and in vivo grown rhizome buds as explants. In vitro and in vivo grown rhizome buds were cultured on MS basal medium with 3 different compositions of growth regulators (1, 0.2 mg l-1 NAA with 1 mg l-1 BA and 0.2 mg l-1 IAA with 1 mg l-1 BA). Cultures were incubated in 18 ± 1°C at 16 h photoperiod. Four subculture of explants were done on the same fresh media with 3 weeks intervals. The results showed that in vivo rhizome bud produced the largest number of small rhizome and roots on medium containing 0.2 mg l-1 NAA with 1 mg l-1 BA.

An experiment was conducted in order to investigate the effects of exogenous polyamines (PAs) on the development of mycorrhizae in roots, nutrient uptake and vegetative and reproductive growth ofFreesia hybrida‘Golden Wave’. Corms of freesia were inoculated withRhizophagus intraradicesat sowing time and treated once a week by one of three PAs, putrescine (Put), spermidine or spermine, in concentrations of 0.05 and 0.1 mM each as foliar application or soil drench. Application of PAs, especially as soil drench, increased mycorrhizal colonization as well as the growth and development of inoculated plants. Among the three PAs, Put in 0.1 mM concentration was the most effective in increasing colonization, enhancing floral stem length and diameter, floral spike length, floret number on main and lateral spikes and increasing corm and cormlet weight, corm diameter and cormlet number. Sole application of arbuscular mycorrhizal fungi had no significant effect on the flowering time but soil drench with 0.1 mM Put accelerated flowering by about 17 days. Application of PAs elevated leaves N, P, K, Mg, Fe and Zn and corms’ P, K, Ca, Fe and Zn concentration of inoculated plants. Our results suggest that soil drench application of PAs, especially Put, positively influenced mycorrhizal inoculation and nutrient uptake, which leads to improving growth, flower and corm production and quality of mycorrhizal plants of freesia.