1,721,098 research outputs found
Ciliegio ad alta e media densità: gestire suolo, acqua e nutrienti
No full textI sistemi d’impianto ad alta e media densità per il ciliegio sono divenuti realtà anche grazie al nuovo materiale genetico. Per garantirne continuità di produzione è però fondamentale conoscere le caratteristiche fisiologiche e produttive di varietà e portinnesti in modo da gestire adeguatamente irrigazione e fertilizzazion
The fate of contaminants of emerging concern in wastewater-irrigated cherry trees: a preliminary assessment
Full text linkClimate change is limiting the availability of conventional irrigation water sources. The
adoption of wastewater reuse could be a valid alternative to face irrigation water shortages.
Unfortunately, current wastewater purification plants are often not equipped to eliminate contaminants of emerging concern (CECs). Consequently, treated wastewater used for crop irrigation could pollute
soils and plants with unknown effects of accumulation, biodegradation, and ab-/adsorption. The present
study evaluates, on potted cherry trees irrigated with municipal treated wastewater, the potential accumulation/
translocation of CECs in soil and plant matrices. From 17 CECs found in the wastewater, only
a few were found at a concentration above 2 μg/L (i.e., Candesartan and Hydrochlorothiazide).
Furthermore, only Candesartan and Hydrochlorothiazide were detected in the soil medium, while no
CECs were found in plant tissues (leaf). Further studies are necessary to better understand the different
CECs behavior and pathways in the water-soil-plant continuum. This should go together with an implementation
of analytical methods for the detection of CECs and related metabolites
Kiwifruit ecophysiological adaptations under moderate and severe deficit irrigation
Full text linkPrecision irrigation scheduling in fruit crops requires good knowledge of water relations. Knowing plants’ behavior and the strategies to be adopted under water stress allows irrigation scheduling to maximize water productivity and minimize water losses. Therefore, the aim of this study is (i) to analyze the relationships between sap flux density, leaf stomatal conductance and fruit diameter daily fluctuations, understanding the water dynamics among plant tissues, and (ii) to understand the effect of deficit irrigation on the fruit size and quality. Actinidia chinensis var. chinensis vines were submitted to four irrigation treatments, applied as percentages of crop evapotranspiration (ETc): 100 %, 68 %, 57 % and 40 % of ETc. Four vines per treatment were monitored with sap flow probes, using the Tmax method, and the same vines had fruit gauges installed to obtain continuous measurements of fruit diameter variations. Measurements of leaf gas exchange were performed throughout the day on six days during the season. Fruit dry matter content was also measured three times during the season and at harvest, together with fruit quality parameters (soluble solids content, firmness, and titratable acidity) at harvest. The comparison of the daily dynamics of sap flux density and leaf stomatal conductance reveals that sap flow continues rising after the beginning of stomatal closure, indicating refilling of storage tissues such as branches and leaves. However, fruit refilling starts at night, when there is less competition for water. Fruit average diameter (Øf) was significantly higher at the 68 % ETc treatment in comparison to control (100 % ETc), being this also significantly higher than the other deficit irrigation treatments (57 % and 40 % ETc). A vapor pressure deficit threshold was identified, above which stomata start to close, regardless of irrigation treatment. Deficit irrigation affected negatively kiwifruit vines sap flux density. Optimized irrigation management, avoiding overirrigation, might lead to higher fruit dry matter content without significantly reducing fruit diameter
Early apple fruit development under photoselective nets
Full text linkThe objective of this 2-year study (2017, 2019) was to evaluate the influence of photoselective nets on apple fruit growth, focusing on the initial fruit growth stages of “Pink Lady”. Trees were subjected to four photoselective nets (Blue, Red, White and Yellow) and a standard black one (serving as Control), resulting in 5 light environments (LE), all shading at 20%. From 20 to 90 DAFB, 32 fruit and extension shoots, for each LE, were measured for a total of 11 times during the season. For each LE, fruit gauges were also installed to monitor fruit daily growth parameters, from 50 to 90 DAFB. At harvest, all fruit from each light environment were weighed and quality parameters were measured on 40 fruit per treatment. For each year, correlations were made to test the influence of LEs on final fruit weight and quality, and the impact that extension shoot growth had on fruit growth. In both years, white and control nets led to the production of fruits with higher weight compared to the other treatments (blue, red and yellow nets). In 2019, LEs did not appear to influence the relationship between shoot and fruit growth, probably due to the higher crop load and the massive pruning carried out the previous year. The higher vegetative outburst in this year might have unbalanced resources towards the shoots, than towards the fruit. Results show how weather and orchard management heavily influenced the trees responses. Yet, the consistent findings of final fruit weight, for both years, indicate that different wavelengths influence fruit and shoot behavior, even at early phenological stages. Hence, growers searching for bigger fruit should refer to white and black nets. Further studies approaching this technology can help improve apple production management and knowledge of the use of photoselective nets
Beneficial effect of secondary treated wastewater irrigation on nectarine tree physiology
No full textIrrigation with secondary treated wastewater (STW) as a support to traditional irrigation management is becoming a necessary alternative to addressing issues of water shortage and fertilizer saving. The application of STW on young potted plants of Prunus persica (L.); cv: Big Top, grafted on GF 677, was studied outdoors on two consecutive seasons, during which three different irrigation treatments were compared: 1) irrigation with STW; 2) irrigation with tap water with the addition of mineral fertilizer (TW + MF) and 3) irrigation with tap water (TW). To assess the effects of the different irrigation treatments, tree nutritional status, shoot growth, Stem Cross Sectional Area (SCSA), Trunk Cross Sectional Area (TCSA), leaf gas exchanges, plant water status, fruit growth, fruit yield and quality were monitored during both seasons. Tree nutritional status, vegetative growth, TCSA, cumulative plant photosynthesis, fruit growth and yield were positively influenced by STW irrigation, compared to TW. TW + MF trees showed the highest vegetative growth and vegetative/reproductive ratio. This induced a rise in their water use and a consequent decrease in stem water potential, indicating the onset of water stress conditions. Results indicated that there was no negative effect of STW application on any of the monitored parameters. STW partially improved the plant physiological, nutritional and productive performances due to its intrinsic fertilizing effect. These results encourage further studies on the possibilities to directly use STW as an alternative source for irrigating and fertigating fruit crops even in open field conditions
Cladode growth dynamics in Opuntia ficus-indica under drought
No full textCactus pear (Opuntia ficus-indica L. Miller) is a CAM plant with an extraordinary capacity to store water in its succulent stems (cladodes). However, the daily variations of cladode thickness is unknown. Studying cladode thickness fluctuations may be useful for the early prediction of plant dehydration stress. The objective of this study was to determine if age, water availability and temperature influence diel cladode shrinkage and enlargement dynamics in cactus pear. The experiment was conducted in a greenhouse from April to July 2014, using cactus pear plants, equally split into irrigated and unirrigated treatments, and unrooted cladodes detached from mother plants. Soil moisture content (SMC), soil water depletion over 24-h, cladode relative water content (RWC), cladode thickness, stomatal conductance (gs), cladode growth rates (area increase) and nocturnal malic acid accumulation were monitored in plants of various ages. Cladode shrinkage and enlargement dynamics were assessed using stem gauges and expressed as absolute growth rate (AGRthickness, μmmin-1). In unirrigated pots, drought decreased SMC, RWC,cladode thickness, cladode growth rate and gs. Younger cladodes lost water later than older ones. Detached cladodes exhibited gs activity 3-4 months after detachment. Trends of AGRthickness showed that there was a progressive reduction of diel swelling and shrinkage fluctuations as cladodes aged. Such fluctuations were minimized under severe drought when 1-year-old cladodes reached 8mm thickness and a RWC of about 45%. A positive correlation was found between SMC and AGRthickness. Temperatures were also directly correlated with AGRthickness, although this relationship was gradually lost as SMC decreased. Overall, cactus pears were able to maintain some growth at very low hydration levels, and cladode growth was highly responsive to rehydration after long periods of drought
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The Growth of the Kiwifruit in its Final Stages
No full textThe growth of nine fruit of Actinidia deliciosa ‘Hayward’ (kiwifruit) was monitored over several days in September 2005, during the last stage of fruit growth, using highly sensitive, custom-built fruit diameter gauges, which allow determination of minute variations in fruit size. These gauges were placed on fruit which, after their growth had been monitored for a few days, were subjected to girdling of the cane above and below the fruit, so to sever the phloem connection; subsequently, the fruit was detached and left in the same position in the canopy. The fruit gauges were left on the fruit throughout. Data collected allowed determination of: total fruit growth; the component of that growth due to phloem and to xylem contributions, and water loss by transpiration. In addition, an automated custom-built open system was used for direct measurement of fruit transpiration over time.
Fruit were examined at the specific time of the season, which is indicated in the literature as the one when loss of xylem and fruit trichome functionality occurs. The goal of this preliminary study was to verify experimentally whether xylem and fruit transpiration were reduced to zero at this time. Fruit grew slowly over the entire period of study (about 10 days in September), and the changes due to xylem inflow-outflow from the fruit were virtually zero, as was the shrinkage of fruit due to transpiration losses. These results confirm previous observations that, at the beginning of the third stage of fruit growth, there are no changes in fruit volume due to xylem flows, and to transpiration losses via the skin. These observations, coupled to the increase in dry matter content reported for the same time of the season, indicate that at stage 3 in kiwifruit an active model of phloem unloading must be adopted. In fact, without xylem and transpiration contributions to the fruit daily shrinking and enlarging, it would be difficult for the fruit to adjust its osmotic properties and turgor pressure in order to attract more solutes from the phloem by bulk flow (as appears to be the case in peach at stage III, for example). These data support either a diffusion based process of phloem unloading, or an active apoplastic mechanism. A careful examination of the velocity of fruit weight increase might shed some light on the type of process involved in phloem unloading
EFFECT OF MODERATE LIGHT REDUCTION ON ABSORBED ENERGY MANAGEMENT, WATER USE, PHOTOPROTECTION AND PHOTO-DAMAGE IN PEACH
No full textNet carbon assimilation increases with irradiance to a saturation point, above which absorbed light is in excess. Besides the temperature increase, with attendant water losses, light excess can increase the photoinhibition risks due to Reactive Oxygen Species (ROS) production. Plants developed a multi-pronged and synergistic photoprotective strategy involving the thermal dissipation, via the xanthophylls cycle, and the photochemistry transports (alternative electron transports and photorespiration). Plants, however, cannot completely avoid photo-damage, and have developed an effective, efficient and energy-dependent recovery system to repair the damaged photosystem II (PSII). This study reports the effect of 40% neutral shading of peach leaves on their gas exchange parameters, the absorbed energy management, and the PSII damage susceptibility during the day. Light reduction did not affect net carboxylation but, decreasing stomatal conductance and temperature under the highest daily irradiance, it increased water use efficiency (WUE). During the same time of the day the xanthophylls cycle quenched more energy in CTRL than in SHD, dissipating 65 and 50% of the absorbed energy, respectively. On the contrary SHD funnelled more energy to photochemistry than CTRL probably because at medium-low irradiance the xanthophylls cycle is pH limited. The susceptibility of PSII to photoinhibition was similar between the two treatments as the same exponential decay of the active PSII against the photon exposure (light intensity × time of exposure) was recorded. The maximal amount of active PSII damaged by a photon unit (Quantum yield of photoinactivation, Qy) was also not influenced by light reduction therefore, the more the absorbed photons, the more the photo-damage to be repaired (at energy cost). These preliminary results suggests that optimizing light interception can ameliorate the plant water use efficiency, without affecting net carbon assimilation and reducing carbon and energy costs for photosystems recovery
- …
