Effect of seawater concentration on the productivity and nutritional value of annual Salicornia and perennial Sarcocornia halophytes as leafy vegetable crops

The halophyte Salicornia was recently introduced as a fresh vegetable crop that thrives in extreme salt conditions. Two annual Salicornia and two perennial Sarcocornia ecotypes were investigated for yield production and nutritional value in response to different seawater concentrations in the irrigation solution. A harvest schedule based on a three-week cycle gave better productivity than a two-week or a four-week cycle. Total yield declined with increasing percentage of seawater above 50% in the irrigation water, however annual plants had always ca 2–3-fold higher fresh biomass in comparison to their perennial counterparts. Increased percentages of seawater in the irrigation solution had the following effects on ion concentrations in the shoots: no change in Ca²⁺ and Mg²⁺, a slight increase in K⁺, and marked elevations in Na⁺ and Cl⁻. Importantly, total polyphenol, β-carotene and ureides, all known for their antioxidant capacities, rose with increasing seawater percentage, findings that indicated improved nutritional values for Salicornia and Sarcocornia irrigated with high concentrations of seawater. Impressively, both the annual Salicornia and the perennial Sarcocornia ecotypes exhibited high total shoot lipid contents of up to 2.41 and 2.06 mg g⁻¹ fresh weight, respectively, which included an omega-3 fraction of 47.6 and 41.2% of the total fatty acid content. Moreover, the high fatty acid content of the annual Salicornia ecotype was not significantly affected by increasing seawater concentrations. In this study, we thus demonstrated the feasibility of cultivating Salicornia and Sarcocornia by applying a multiple harvest system and 100% percentages of seawater in the irrigation water generating economic yields with high nutritional value. The findings also showed that Salicornia and Sarcocornia leafy vegetables may attract additional interest as an alternative source of omega-3 polyunsaturated fatty acids for human consumption, even when the crop irrigated solely with seawater.     

Effects of day length on flowering and yield production of Salicornia and Sarcocornia species

Salicornia is a new vegetable crop that can be irrigated with highly saline water, even at salt concentrations equivalent to full-strength seawater. During leafy vegetable cultivation, the onset of the reproductive phase is an undesired phenomenon that reduces yield and quality and prevents year-round cultivation. Knowledge about the regulation of floral induction in the members of the tribe Salicornieae, however, is lacking. To establish year-round cultivation, we studied the flower induction of five Salicornia and two Sarcocornia varieties. Plants were grown under two day lengths, 13.5 h and 18 h, and harvested by a repetitive harvest regime. A 13.5-h day length prevented flower induction in the Israeli Salicornia varieties, but a longer day length was required to prevent flower induction in two species originating from more northern latitudes. The onset of the reproductive phase under suboptimal short day length conditions severely reduced vegetative growth and yields in Salicornia. In Sarcocornia, the repetitive harvest regime prevented flowering, making it a promising candidate for year-round cultivation. Irrigating the plants with full-strength seawater (electrical conductivity 48 dS m⁻¹) vs. water with moderate salinity (electrical conductivity 10 dS m⁻¹) did not change the general flowering pattern of the studied Salicornieae members.     

Aphids detect approaching predators using plant-borne vibrations and visual cues

Journal of Pest Science - Aphids (Hemiptera: Aphididae) have a repertoire of defensive behaviors against insect predators and parasitoids that includes kicking, twitching, walking away and dropping...     

Dynamics of phosphorus phytoavailability in soil amended with stabilized sewage sludge materials

Reducing the environmental risk of soluble P loss from sludge-amended soils is essential for increasing soils capacity to utilize sewage sludge beneficially. Fresh dewatered anaerobically digested sewage sludge (FSS), stabilized with ferrous sulphate (FeSul–SS), calcium oxide (CaO–SS) and aluminum sulphate (alum–SS), each at three chemical-to-FSS ratios, or by composting (BSC), was applied to alluvial soil at rates of 150 and 300 mg P kg^? 1 soil. Changes in P phytoavailability in comparison to KH₂PO₄-amended soil were probed during 100 days of incubation by a P-bioassay and were compared to the concentration of water-soluble P (WSP) and Olsen-P. P phytoavailability was notably linked to the incubation duration and the stabilization process. In general, P phytoavailability at equal P-addition rates was KH₂PO₄ > > alum–SS > BSC ≥ FSS > CaO–SS > > FeSul–SS; and it was positively related to the added P rates, although with quite different patterns among the various sludge products. The concentration of inorganic WSP (WSP_i) extracted from the soil increased following the application of FSS or BSC, and additional P mineralization further increased its concentration during incubation. In contrast, in most cases the chemically stabilized sludges, especially the FeSul–SS, showed considerably reduced inorganic WSP concentrations relative to the untreated soil. The total WSP, Olsen-P and organic WSP (WSP_o) positively correlated to P phytoavailability, indicating that WSP_o plays a role in plant P utilization in these soils. It is concluded that all the chemically stabilized sewage sludge studied effectively controlled WSP_i in soil while still supplying P to support plant growth.     

贝莱斯芽胞杆菌B006对不同水肥条件下娃娃菜生长及软腐病防效的影响

贝莱斯芽胞杆菌B006是一株高效生防菌株,但其在不同水肥条件下的防病促生效果尚不明确。本研究通过盆栽试验测定了不同土壤含水量和施肥条件下B006菌剂对娃娃菜生长及对软腐病防效的影响,结果表明：在土壤含水量为14%、施肥量为3.57 g/kg土的条件下,播种时沟施5 g B006菌剂（菌含量为1×10⁷ CFU/g）,出苗后浇灌B006菌悬液（3×10⁸ CFU/mL）可明显降低娃娃菜的发病率和病情指数,与相同条件下未施用B006菌剂处理相比,防效达77.4%。在日光温室开展土壤水势、施肥量及B006菌剂施用随机区组交互试验,结果表明：在土壤水势—50 kPa和追肥量1049.5 kg/hm²（N/P/K=18/5/13）条件下,施用B006菌剂可以促进植株生长,与土壤水势和追肥量分别为—50 kPa×1499.3 kg/hm²和—30 kPa×1499.3 kg/hm²的处理相比,娃娃菜产量分别提高了8.6%和11.2%。综上所述,适当少水、少肥并施用贝莱斯芽胞杆菌B006菌剂可以明显控制娃娃菜软腐病的发生,促进植物生长,并显著提高娃娃菜产量。     

Life-table analyses for the tomato leaf miner,Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae): effects of plant genotype

BACKGROUND

Host plant resistance plays an important role in integrated pest management programs. Crop resistance assessments commonly focus on only a single dependent variable, such as larval survival/plant damage, which limits the ability to appreciate the impact of host plants on pest populations in the full sense. Therefore, we performed life-table analyses for tomato leaf miner Tuta absoluta, on 19 Solanum lycopersicum genotypes and a wild Solanum habrochaites accession. These analyses assess the ability of the pest to attain a high population density on different tomato genotypes. Based on the resulting ranking of tomato resistance at the vegetative stage (45-day-old plants), we tested the resistance of six selected genotypes at the reproductive stage (4-month-old plants).

RESULTS

T. absoluta performance was significantly inferior on vegetative-stage S. habrochaites plants (LA 1777); time taken for the first instars to mine the leaves (5 ± 0.14 days), development time of early- and late-stage larvae (8.8 ± 0.2 and 4.2 ± 0.2 days, respectively), pupal period (11.2 ± 0.58 days), and total developmental time (29.4 ± 0.83 days) were significantly longer, fecundity was significantly lower (18.66 ± 7.24 days), and the highest total mortality (63.33%) also recorded compared with other genotypes, resulting in the lowest net reproductive rate (R₀) (11.20 ± 2.51). For the six selected genotypes, the ranking of plant resistance did not change between plants at the vegetative and reproductive stages.

CONCLUSION

This study suggested that of 20 screened tomato genotypes, LA 1777 and EC-620343 are the least suitable hosts for T. absoluta to establish fast-growing populations, and thus can be employed in integrated T. absoluta management. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Bioassays using detached tobacco leaves to determine the sensitivity of Peronospora tabacina to fungicides

Two bioassay methods are described which use detached tobacco leaves to measure the sensitivity of Peronospora tabacina to systemic fungicides. Tobacco leaves (13–15 cm²), treated with fungicides before or after detachment from the plant, were inoculated with sporangia in water drops and, after incubation in beakers and Petri plates, the disease severity and/or production of sporangia was determined 4–7 days after treatment with the fungicides. Of 15 systemic fungicides applied to detached leaves, eight N-phenylamides at 0.066?1.0 μg ml^?1 controlled blue mould; metalaxyl was the most effective fungicide. Isolates of P. tabacina, collected in the field from tobacco plants grown in soil treated with metalaxyl, were not resistant to the fungicide applied to detached leaves prior to inoculation. The fungicide, applied to leaves before detachment, was used to measure the efficacy of five systemic N-phenylamide fungicides sprayed on the basal and unsprayed distal portions of the leaves. Blue mould was controlled on the basal portion of the leaf by all the fungicides at 0.66?1.0 μg ml^?1, but it required the application of 3–30 times more chemical on the basal portion to achieve comparable blue mould control on the distal part of the leaf.     

Movement and distribution of ethylene in plants in relation to the regulation of growth and development

Work is described showing that ethylene does not move about the plant in physiologically significant amounts due to resistance in the longitudinal direction and loss by emanation from the surface of the plant. Nevertheless, changes in ethylene concentration in one part of the plant may influence concentrations in other parts. It is shown that the partition coefficients for ethylene between air and various plant organs are relatively high and may change in the course of development. These results are discussed in relation to compartmentation of ethylene within the plant and the possible implications of such compartmentation for the control of plant growth and development.