Yield response of corn to irrigation and nitrogen fertilization in a Mediterranean environment

Productivity and resource-use efficiency in corn (Zea mays L.) are crucial issues in sustainable agriculture, especially in high-demand resource crops such as corn. The aims of this research were to compare irrigation scheduling and nitrogen fertilization rates in corn, evaluating yield, water (WUE), irrigation water (IRRWUE) and nitrogen use (NUE) efficiencies. A 2-year field experiment was carried out in a Mediterranean coastal area of Central Italy (175 mm of rainfall in the corn-growing period) and corn was subjected to three irrigation levels (rainfed and supply at 50 and 100% of crop evapotranspiration, ETc) in interaction with three nitrogen fertilization levels (not fertilized, 15 and 30 g (N) m⁻²). The results indicated a large yearly variability, mainly due to a rainfall event at the silking stage in the first year; a significant irrigation effect was observed for all the variables under study, except for plant population. Nitrogen rates affected grain yield plant⁻¹ and ear⁻¹, grain and biomass yield, HI, WUE, IRRWUE and NUE, with significant differences between non-fertilized and the two fertilized treatments (15 and 30 g (N) m⁻²). Furthermore, deficit irrigation (50% of ETc) was to a large degree equal to 100% of the ETc irrigation regime. A significant interaction “N × I” was observed for grain yield and WUE. The effect of nitrogen availability was amplified at the maximum irrigation water regime. The relationships between grain yield and evapotranspiration showed basal ET, the amount necessary to start producing grain, of about 63 mm in the first and 206 mm in the second year. Rainfed crop depleted most of the water in the 0–0.6 m soil depth range, while irrigated scenarios absorbed soil water within the profile to a depth of 1.0 m. Corn in a Mediterranean area can be cultivated with acceptable yields while saving irrigation water and reducing nitrogen supply and also exploiting the positive interaction between these two factors, so maximizing resource-use efficiency.     

Detection and characterization of phytoplasmas in diseased stone fruits and pear by PCR-RFLP analysis in Turkey

During the late summer-early autumn of 2002, surveys were carried out in Turkey to determine the presence of phytoplasma diseases in fruit trees. Phytoplasmas were detected and characterized by PCR-RFLP analysis and TEM technique in stone fruit and pear trees in the eastern Mediterranean region of the country. Six out of 24 samples, including almond, apricot, peach, pear and plum, gave positive results in PCR assays. RFLP analysis usingSspI andBsaAI enzymes of PCR products obtained with primer pair f01/r01 enabled identification of the phytoplasmas involved in the diseases. Stone fruit trees, including a local apricot variety (‘Sakıt’) and a pear sample, were found to be infected with European stone fruit yellows (ESFY, 16SrX-B) and pear decline (PD, 16SrX-C) phytoplasmas, respectively. This is the first report in Turkey of PD phytoplasma infecting pear and of ESFY phytoplasma infecting almond, apricot, myrobalan plum and peach; ESFY phytoplasma infecting Japanese plum was previously reported. http://www.phytoparasitica.org posting July 21, 2005.     

Pasteurized tumoral autograft and adjuvant chemotherapy for the treatment of canine distal radial osteosarcoma: 13 cases

OBJECTIVE: To report outcome in 13 dogs with distal radial osteosarcoma, without evidence of metastasis, treated by a combination of adjuvant chemotherapy and a pasteurized autograft limb-sparing procedure. STUDY DESIGN: Prospective clinical study. ANIMALS: Thirteen dogs with distal radial osteosarcoma. METHODS: Limb-sparing procedure was performed using an autograft from the excised tumoral segment, pasteurized at 65 degrees C for 40 minutes. Adjuvant chemotherapy (cisplatin or cisplatin and doxorubicin) was administered in all dogs. RESULTS: Mean and median survival times were 531 and 324 days, respectively (range, 180 to 1,868 days). Overall survival was 100% at 6 months, 50% at 12 months, 44% at 18 months, and 22% at 24 months. Lung metastasis occurred in 5 (38%) dogs. Observed complications were local recurrence (2 dogs, 15%), allograft infection (4 dogs, 31%), and implant failure (3 dogs, 23%). Limb function was good in 12 dogs (92%) and fair in 1 dog. CONCLUSIONS: Pasteurized bone autograft derived from the tumoral bone segment was an effective alternative to cortical bone allograft for limb sparing in canine distal radial osteosarcoma, in terms of feasibility, pattern of healing, complications, and survival. CLINICAL RELEVANCE: Use of a pasteurized bone autograft eliminates the need for a canine bone allograft bank and has the added advantage of good fit to the recipient site.     

Calcium mineral nutrition increases the tolerance of Quercus ilex to Phytophthora root disease affecting oak rangeland ecosystems in Spain

Root rot caused by the soil-borne pathogen Phytophthora cinnamomi is leading to significant oak tree mortality in rangeland ecosystems in south western Spain. Susceptibility to P. cinnamomi infections of Q. ilex seedlings with a standard nutrition, deficient in K⁺, and deficient in Ca²⁺, was tested. Oaks deficient in K⁺ showed high values in Ca²⁺ content and were tolerant to the disease. Nutritional deficiency in Ca²⁺, however, did not lead to a higher K⁺ level in plants and induced poorer root development. In addition, K⁺ plant content does not appear to have any effect on pathogen tolerance. Based on these results, we conclude that satisfactory calcium nutrition may confer Holm oaks with a greater tolerance to root disease caused by P. cinnamomi. For this reason, limestone supplements are recommended as a measure against root rot caused by P. cinnamomi in rangelands in southern Spain, as a good option for control of oak root disease.     

Role of EDEM in the release of misfolded glycoproteins from the calnexin cycle

The mechanisms that determine how folding attempts are interrupted to target folding-incompetent proteins for endoplasmic reticulum-associated degradation (ERAD) are poorly defined. Here the alpha-mannosidase I-like protein EDEM was shown to extract misfolded glycoproteins, but not glycoproteins undergoing productive folding, from the calnexin cycle. EDEM overexpression resulted in faster release of folding-incompetent proteins from the calnexin cycle and earlier onset of degradation, whereas EDEM down-regulation prolonged folding attempts and delayed ERAD. Up-regulation of EDEM during ER stress may promote cell recovery by clearing the calnexin cycle and by accelerating ERAD of terminally misfolded polypeptides.     

Intra-varietal genetic diversity of the grapevine (<Emphasis Type="Italic">Vitis vinifera</Emphasis> L.) cultivar ‘Nero d’Avola’ as revealed by microsatellite markers

The Sicilian grape cultivar ‘Nero d’Avola’ is among the oldest and most cultivated in the island, taking part in the production of several red wines exported worldwide, including DOC wines (Etna Rosso and Cerasuolo di Vittoria). Due to the ancient origin and repeated clonally propagation of the cultivar, phenotypic variability has been observed. Clone identification in this important cultivar has so far relied on phenotypic and chemical traits analyses, often affected by environmental conditions. Genetic markers, such as microsatellites, are particularly useful for cultivar identification, parentage testing, pedigree reconstruction and population structure studies. In the present paper, microsatellites were used to analyze the intra-varietal genetic diversity among 118 plants of ‘Nero d’Avola’, collected in 30 vineyards displaced in different areas of Sicily. Out of 22 microsatellites, 11 showed polymorphism among samples and 15 different phylogenetic groups were identified. Results show that ‘Nero d’Avola’ actually comprises different genetic profiles, although most of clones share a common origin.     

Phenotypic recurrent selection in common bean (Phaseolus vulgaris L.) based on performance of S2 progenies

Summary The effect of a recurrent selection procedure for improving seed yield per plant was evaluated in common bean. Progress was registered after three cycles of recurrent selection with S2 progeny evaluation performed on the grain yield/plant. Gain from selection was estimated by field testing 45 random S2 lines from each of the C0, C1 and C2 populations. Response to selection for seed yield/plant was 6 g from C0 to C1 and 4.4 g from C1 to C2. The seed yield improvement was due principally to an increase in pods/plant; little contribution was provided by the 1000-seed weight and seeds/pod traits. Broad-sense heritability and genotypic variance for grain yield remained high in all cycles which suggests further gain from additional selection cycles. Grain yield/plant is significantly correlated to pods/plant and seeds/pod traits in all cycles, indicating that plants with favourable combinations of these traits could be identified. The proposed recurrent selection procedure appears to be effective in improving the population and extracting superior genotypes for varietal development.     

Photoinhibition of photosynthesis in needles of two cypress (Cupressus sempervirens) clones

Photoinhibition of photosynthesis and photosynthetic recovery were studied in detached needles of cypress (Cupressus sempervirens L.) Clones 52 and 30 under controlled conditions of high irradiation (about 1900 micromol m(-2) s(-1) for 60 min; HL treatment), followed by 60 min in darkness. The degree of photoinhibition was determined based on the ratio of variable to maximum chlorophyll fluorescence (Fv/Fm), which is a measure of the potential efficiency of photosystem II (PSII), and on electron transport measurements. The Fv/Fm ratio declined in needles of both clones in response to the HL treatment. Minimal fluorescence (Fo) increased in HL-treated needles of both clones. The HL treatment decreased rates of whole-chain and PSII activity of isolated thylakoids more in Clone 52 than in Clone 30. In needles of both clones, PSI activity was less sensitive to photoinhibition than PSII activity. In the subsequent 60-min dark incubation, fast recovery was observed in needles of both clones, with PSII efficiencies reaching similar values to those in non-photoinhibited needles. The artificial exogenous electron donors diphenyl carbazide (DPC), hydroxylamine (NH2OH) and manganese chloride (MnCl2) failed to restore the HL-induced loss of PSII activity in needles of Clone 30, whereas DPC and NH2OH significantly restored PSII activity in photoinhibited needles of Clone 52. Quantification of the PSII reaction center protein D1 and the 33-kDa protein of the water-splitting complex following HL treatment of needles revealed pronounced differences between Clone 52 and Clone 30. The large decrease in PSII activity in HL-treated needles was caused by the marked loss of D1 protein and 33-kDa protein in Clone 30 and Clone 52, respectively.