Role of extrafloral nectaries of Vicia faba in attraction of ants and herbivore exclusion by ants

Acacia pycnantha secreted extrafloral nectar during winter. This coincided with flowering and not with herbivore damage to phyllodes. Phyllodes with axillary racemes or phyllodes towards the tips of branches were more likely to have nectar secretions than phyllodes without axillary racemes or away from the tips of branches. Although most phyllodes were damaged by herbivores to some extent, this damage had occurred prior to the secretion of extrafloral nectar in winter. Further damage to phyllodes was negligible during winter. A variety of birds, including silvereyes and several species of honeyeaters and thornbills, consumed extrafloral nectar and in the process brushed against inflorescences. The activity of these birds in Acacia pycnantha, relative to their use of other plants, increased during the period of nectar secretion. When birds were excluded from flowering branches by mesh, pod production was significantly reduced. Natural rates of pod production were low and variable. These observations and results strengthen the role of birds as pollinators of Acacia pycnantha and we argue that these extrafloral secretions aid pollination and not reduction in herbivore damage in Acacia pycnantha.

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Role of some rhizospheric Pseudomonas on the growth and physiology of broad bean (Vicia faba) under salt stress conditions

Acta Agrobotanica ◽

10.5586/aa.1794 ◽

2019 ◽

Vol 72 (4) ◽

Author(s):

Boubaker Idder ◽

Rachid Djibaoui ◽

Hocine Abdelhakim Reguieg Yssaad ◽

Abdelhak Djoudi

Keyword(s):

Salt Stress ◽

Chlorophyll Content ◽

Vicia Faba ◽

Broad Bean ◽

Plant Growth Promoting Bacteria ◽

Total Chlorophyll ◽

Plant Tolerance ◽

Bacterial Strains ◽

Total Chlorophyll Content

Salt stress affects the development and growth of plants in various ways as a result of its effect on water relationships, photosynthesis, and nutrient absorption by physiological and biochemical processes. Consequently, several researchers have increasingly studied the effect of plant growth promoting bacteria (PGPR) as promoters and enhancers under saline environment. The main goals of this study were to examine the manifested response of the broad bean plant under saline conditions and to evaluate the role of some Pseudomonas isolates in improving plant tolerance to salt stress. Three Pseudomonas strains were isolated (P1 and P7 from a saline soil and P15 from a vineyard soil). These isolates were screened by salinity and used as inoculums in Vicia faba plants (OTONO variety) irrigated with two saline solutions (NaCl; 100 and 150 mM L−1) and one without salinity. The results show that salinity decreased the fresh weight, total chlorophyll content, and the Na+/K+ ratio, but it increased proline accumulation in inoculated and noninoculated plants. The inoculation of V. faba plants with P1, P7, and P15 strains significantly increased the production of fresh biomass in the presence and absence of salt stress, and positively affected the accumulation of proline and the Na+/K+ ratio. The inoculation with bacterial strains increased the total chlorophyll content in plants at all salt treatment levels, especially the P1 strain that showed a significant effect.

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