Differential tolerance of the woody invasive Hakea sericea to drought and terminal heat stress.

Drought and extreme temperatures are likely to be more common and intense in the Mediterranean region as a consequence of climate change. Both stresses usually arise together in the field, but our understanding of their joint influence on the performance of invasive alien species (IAS) is limited. Thus, the main objective of the present study is to fill this gap by analyzing the individual and combined effects of drought and terminal heat stress on the leaf physiology, biochemistry and growth of Hakea sericea Schrader, one of the most problematic IAS in the Mediterranean-type ecosystems. In this study, 1-year-old plants of H. sericea were exposed to four treatments under controlled conditions: control (CT), drought (DS), terminal heat stress (Ht), and combined Ht and DS (DHt). The DS treatment alone caused a marked reduction in shoot biomass, net photosynthetic (A) rate and stomatal conductance, while increasing the proline content, as compared with CT plants. In turn, the Ht treatment promoted the accumulation of malondialdehyde but hastened the decline in all gas exchange parameters, and also decreased leaf photosynthetic pigments, carotenoids, proline and relative water contents Exposure of H. sericea plants to the combined DHt exacerbated the impacts of Ht, which was accompanied by significant decreases in net photosynthetic and transpiration rates, and intrinsic water-use efficiency. Principal component analysis clearly separated the DHt from the other treatments and revealed similarities between DS and CT treatment. These findings suggest that xerothermic weather conditions might modify the fitness, competitive ability, resilience and spread of this IAS, thereby providing opportunities for its control.

Comparative study of plant growth-promoting bacteria on the physiology, growth and fruit quality of strawberry.

BACKGROUND: The strawberry (Fragaria × ananassa Duch.) is, among small fruits, the most cultivated and commercialized in Portugal. Recent studies have evidenced the positive effect of plant growth-promoting bacteria (PGPB) inoculation on strawberry production and, at the same time, provided an alternative strategy to reduce the use of fertilizers. In this study the effects of root inoculation with three PGPB strains (Pedobacter sp. CC1, Bacillus safensis B106 and Bacillus subtilis B167A) on the physiology, growth, fruit production and quality of strawberry cv. Camarosa are presented. RESULTS: PGPB inoculation significantly accelerated crop maturation, with inoculated plants fruiting about 2 weeks earlier than non-inoculated plants. Inoculated plants with Pedobacter sp. CC1 and Bacillus safensis B106 influenced the gas exchange parameters of strawberry plants. The contents of total phenolics and flavonoids in strawberry leaves were found to be greater with Pedobacter sp. CC1, when compared with non-inoculated plants. Furthermore, plants inoculated with the same bacterial strain showed enhancement in the dimensions of fruits, especially fruit length, and shape as well as in the total soluble solids content (°Brix). CONCLUSIONS: The results showed that the PGPB Pedobacter sp. CC1 improved performance of strawberry plants, suggesting that it could be a potential biofertilizer for strawberry plant nutrition. © 2019 Society of Chemical Industry.

Incidência e distribuição de amblyomma cajennense em regiões corporais de eqüinos das raças mangalarga marchador e bretão postier, naturalmente infestados / Amblyomma cajennense: adults distribution and incidence on the body of naturally infested mangalarga marchador and bretao postier horses

The objective of this study is to verify the incidence and the distribution of the tick Amblyomma cajennense tick in some infected regions of equines'body. Fifteen animals, 8 mares and 7 colts from Mangalarga Marchador and Bretão Postier races, raised in the Zootechny Institute Farm, Federal Rural University of Rio de Janeiro, were selected. From July, 1996 to May, 1997 (every 21 days) the animals were submitted to examination, mapping and ingurgitated females countig in 14 previously determined regions: face, lower jaw, neck, breast, shoulder-blade, armpits, former limbs, womb, back, flank, hip, udder, posterior limbs and perianal. The observed regions were classified in: anterior, posterior, median, right side and left side. The deviation analysis was made taking into account a random blocks delineation, whose scores were previously transformed on square root in order to decrease their dispersion, and subsequently analyzed by deviation analysis. During the observation time, the total of ticks was 1.434: 55.2 per cent corresponding to the anterior region and 44 per cent to the posterior region. It was also noticed a significant difference - 5 per cent - in June and April, occuring the higher parasitic incidence, regarding to September, with a lower incidence. On the right and left sides and median region of the animals body, the variation was: 27.7 por ciento, 30.1per cent and 42.2 per cent, respectively. The counting was higher in June; however, from August to September have showed lower incidences. On mares the distribution was: 59.5 per cent on the anterior region and 40.5 per cent on the posterior region: 32.9 per cent on the right side, 28.1 per cent on the left side and 39 per cent on the median region. It was noticed significative difference among the countings averages on the three last regions in June (with higher incidence) and averages December, May, September, January and February averages (with lower incidences, respectively).