RAPD genetic diversity of Albanian olive germplasm and its relationships with other Mediterranean countries

RAPD markers were used for the study of 19Albanian olive cultivars and two wild olives (oleasters). A total of 76polymorphic bands (4.8 polymorphic markers per primer) out of 107 reproducible were obtained using 16 primers. The number of bands per primer ranged from 4 to 10,whereas the number of polymorphic bands ranged from 1 to 9, corresponding to 71%of the total amplification products. All the accessions could be identified by the combination of four primers: OPA-19;OPA-02; OPK-16 and OPP-19. The dendrogram,based on Jaccard's index, included three major groups according to their origin: 1)most of the cultivars from the area of Berat (South of Albania) 2) cultivars from the Centre and Centre-North of Albania and3) cultivars from the Centre and North-West of Albania along with the oleaster from Elbasan. In order to evaluate the origin of Albanian cultivars they were compared to those diffused in other countries like Greece, Italy and Turkey, due to geographical and historical affinity among these countries, by using a one way AMOVA. Although most of the genetic diversity was attributable to differences among cultivars within each country (91.47%) significantφ-values among countries(φ_st = 0.085; p < 0.001)suggested the existence of RAPD phenotypic differentiation. Significant φ-values in all pairs formed by Albania with the other countries were observed. These results are consistent with the autochthonous origin of Albanian cultivars. This revised version was published online in August 2006 with corrections to the Cover Date.     

Evaluation of photosynthesis,physiological, and biochemical responses of chickpea (Cicer arietinum L. cv. Pirouz) under water deficit stress and use of vermicompost fertilizer

One goal in the face of drought stress conditions is to increase growth and yield through the reduction of negative effects of stress. Vermicompost can play an effective role in plant growth and development and in reducing harmful effects of various environmental stresses on plants due to its porous structure, high water storage capacity, having hormone-like substances, plant growth regulators, and high levels of macro and micro nutrients. This study considered the physiological, biochemical, and photosynthetic responses of the chickpea to different combinations of vermicompost and water stress in a greenhouse environment. Two factors were involved, addition of vermicompost to soil at four ratios: control (100 wt% (weight percentage) soil); 10 wt% vermicompost+90% soil; 20 wt% vermicompost+80 wt% soil; 30 wt% vermicompost+70 wt% soil weight percentage, and treatment of water stress at three levels including 75, 50, and 25% of field capacity. The results showed that vermicompost had a significant effect on all traits under stress and non-stress conditions. Application of vermicompost in soil, especially at the levels of 20 and 30 wt% significantly increased all studied traits under non-stress conditions. Under moderate stress conditions, vermicompost at 30 wt% treatment resulted in a significant increase in the photosynthetic pigments, CO₂ assimilation rate, internal leaf CO₂ concentration, transpiration, the maximal quantum yield of photosystem II (PSII) photochemistry (F_v/F_m), concentrations of Ca and K in root and leaf tissues, proline and soluble protein contents in root tissues. Peroxidase (POX) and catalase (CAT) enzyme activities decreased significantly with increasing proportions of vermicompost, but the activity of superoxide dismutase was not significantly different. In conclusion, the above results showed that vermicompost fertilizer had a positive effect on physiological, biochemical, and photosynthetic responses of chickpea under non-stress and moderate stress conditions, but no positive effect was determined under severe water stress.     

Effect of ammonium or nitrate nutrition on photosynthesis,growth, and nitrogen assimilation in tomato plants

Nitrogen (N) is taken up by most plant species in the form of nitrate (NO ) or ammonium (NH ). Plant response to continuous NH nutrition is species‐dependent. In this study, we compare the responses of tomato (Solanum lycopersicum L. cv. Rio Grande) plants to N source (NO or NH ). To this end, early plant growth, photosynthesis, chlorophyll, carbohydrate, and N‐compound concentrations as well as the activities of main enzymes involved in N metabolism (nitrate reductase, nitrite reductase, glutamine synthetase, and glutamate dehydrogenase) were analyzed. Early plant growth was remarkably ameliorated under NH ‐ in comparison to NO ‐based nutrition. Concomitantly, photosynthetic activity, total chlorophyll, and carbohydrate concentrations were significantly increased. With increasing external NH concentration, NH accumulated mainly in roots. In addition, root protein concentration was significantly increased, reflecting high NH incorporation into organic nitrogen. Root glutamine synthetase (GS) activity was enhanced by NH for concentrations below 5 mM, whereas root glutamate dehydrogenase (GDH) activity increased in parallel to NH availability. Together with the positive effect of NH on tomato plant cv. Rio Grande growth, these results reveal that GDH could have, in addition to GS, a possible role in NH detoxification and tolerance of NH ‐based nutrition.     

Identification of a genetic lineage within Xanthomonas arboricola pv. juglandis as the causal agent of vertical oozing canker of Persian (English) walnut in France

A new bacterial disease of Persian (English) walnut (Juglans regia) has been observed in France. This disease, called vertical oozing canker (VOC), is characterized by vertical cankers on trunks and branches of affected walnut trees with oozing exudates. To determine the aetiology of the disease, a study was carried out in 79 walnut orchards and nurseries located in southeastern and southwestern France. Bacterial analysis from diseased samples yielded 36 strains identified as Xanthomonas arboricola and 32 strains identified as Brenneria nigrifluens on the basis of biochemical tests. The causal agent of VOC was identified as X. arboricola by pathogenicity tests on walnut. Fluorescent amplified fragment length polymorphism (F‐AFLP) was carried out on 36 strains of X. arboricola collected in this study, 24 strains of X. arboricola pv. juglandis isolated from walnut blight symptoms and one strain of X. arboricola pv. corylina included as an outgroup. Based on cluster analysis of F‐AFLP data, most X. arboricola strains responsible for main VOC outbreaks showed a high degree of similarity, forming a cluster clearly separate from strains of X. arboricola pv. juglandis isolated from walnut blight symptoms. It is suggested that VOC is caused by a distinct genetic lineage within the pathovar juglandis of X. arboricola that is also able to cause classical bacterial blight symptoms on walnut leaves and fruits.     

Influence of Vermicompost Fertilizer and Water Deficit Stress on Morpho-Physiological Features of Chickpea (Cicer arietinum L. cv. karaj)

One goal in the face of deficit water conditions is to increase growth and yield. Agro-industrial production frequently causes environmental pollution by using chemical fertilizers. In recent decades, bio-fertilizers such as vermicompost have been used as a safe alternative to chemical fertilizer. The present study considered the response of the chickpea to different combinations of vermicompost and water deficit stress in a greenhouse environment. Plant response was determined by measuring a range of morpho-physiologic parameters. The treatments were addition of 0%, 10%, 20%, and 30% of vermicompost to soil, and water deficit stress at the following levels: non-stress (100% of field capacity), moderate water stress (75% of field capacity), and severe water stress (25% of field capacity). The results showed that vermicompost had a significant effect on all traits under stress and non-stress conditions. The vermicompost treatments under non-stress conditions significantly increased plant height, number of pods, leaf area, stem and leaf dry weight, pod dry weight, chlorophyll a, carotenoid, total chlorophyll content, CO₂ assimilation rate, internal CO₂ concentration, and water-use efficiency over that of the control condition. The addition of 30% vermicompost under moderate and severe water stress conditions significantly increased plant height, number of pods, leaf area, leaf dry weight, carotenoids, and water-use efficiency over that of the control level. This study confirmed that vermicompost improved the morphological features, soil biological activity, and quality of the chickpea, but did not positively influence the physiological features under moderate and severe water deficit stress.     

Production and Germination of Oospores of Phytophthora infestans (Mont.) de Bary in Morocco

One hundred and eight isolates of Phytophthora infestans were collected from infected potato and tomato crops in the middle-north of Morocco during 1997–2000. Pairings of these isolates with tester isolates of mating type A1 and A2 revealed that 60% of the isolates were mating type A2 (65/108) and 40% were mating type A1. After 10 days incubation at 20 °C and a 16-h photoperiod, approximately 25% and 18% of the oospores produced in-vitro germinated in potato soil extract and potato root extract, respectively. Oospores were observed in potato leaf tissues in pairings that were fertile in-vitro. Maximum production of oospores was obtained in potato leaves of cultivars that were moderately susceptible (Desirée, Nicola) after 10 days of incubation at 15 °C and a 16-h photoperiod. These results confirm the presence of P. infestans strains that are sexually compatible under Moroccan climatic conditions. Production of oospores constitutes a threat for these crops because of the occurrence of recombinants with new virulences which may be difficult to control and as a consequence survival of oospores in absence of the host plant in the soil.     

Does the source of nitrogen affect the response of subterranean clover to prolonged root hypoxia?

Nitrogen (N) is taken up by most plant species in the form of nitrate (NO ) or ammonium (NH ). The plant response to continuous ammonium nutrition is species‐dependent. In this study, the effects of the source of N nutrition (NO , NH , or the mixture of NO and NH ) on the response of clover (Trifolium subterraneum L. cv. 45C) plants to prolonged root hypoxia was studied. Under aerobic conditions, plant growth was strongly depressed by NH , compared to NO or mixed N nutrition, as indicated by the significant decrease in root and shoot‐dry‐matter production (DW), root and shoot water contents (WC), leaf chlorophyll concentration, and chlorophyll fluorescence parameters (F₀, F_v/F_m). However, the N source had no effect on chlorophyll a–to–chlorophyll b ratio. Under hypoxic conditions, the negative effects of root hypoxia on plant‐growth parameters (DW and WC), leaf chlorophyll concentration, and chlorophyll fluorescence parameters were alleviated by NH rather than NO supply. Concomitantly, shoot DW–to–root DW ratio, and root and leaf NH concentrations were significantly decreased, whereas root and leaf carbohydrate concentrations, glutamine synthetase activities, and protein concentrations were remarkably increased. The present data reveal that the N source (NO or NH ) is a major factor affecting clover responses to hypoxic stress, with plants being more tolerant when NH is the N form used. The different sensitivity is discussed in terms of a competition for energy between nitrogen assimilation and plant growth.     

Nutrition and biochemical responses of chickpea (Cicer Arietinum L.) to vermicompost fertilizer and water deficit stress

Vermicompost can have an effective role in plant growth and nutrition. It can also reduce the harmful effects of stress caused by environmental factors. This study was a factorial experiment with a completely randomized plot design and three replications. The results showed that the calcium concentration (+40% +39%) of root and calcium (+71% +67%) and potassium contents (+49% +59%) of leaf under conditions of moderate and severe water stress increased under vermicompost treatments at the ratio of 30%. Sodium absorption (?37% ?21%) in moderate and severe conditions was significantly reduced by vermicompost treatment. In moderate and severe water stress, the growth medium of 30% vermicompost significantly enhanced proline (+39%) and soluble protein content (+28%) compared to the control. In conclusion, our results proved vermicompost fertilizer due to its structural properties and components, served to reduce the negative effects of water stress by increasing the absorption of calcium (Ca) and potassium (K), and decreasing sodium (Na) absorption that resulted in increased evaluations for proline and protein content.