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Organic fertilization has been proposed as an alternative approach to supply nutrients for crops, in the frame of organic and sustainable agriculture, with the aim to decrease high inorganic fertilization rates, protect the environment and decrease production costs for farmers. Since different types of organic fertilizers, such as manures, olive mill wastewater (OMW), sewage sludge (SS), crushed pruning wastes, composts and cover crops, exist as soil amendments to improve soil fertility, enhance plant nutrition and sustain the productivity of tree crops, their role as biofertilizers has been fully analyzed under the most important published papers. In addition, the benefits and drawbacks of organic fertilization, in a comparative approach with inorganic fertilization, are presented and discussed. Within the most important advantages of organic fertilizers, the enhancement of beneficial soil microorganisms and the improvement in soil physical properties and fertility should be included, while their most important disadvantage is their inability to directly satisfy the prompt N nutritional needs of tree crops, due to slow N mineralization rates. Finally, some novel aspects on the interrelation among innovative organic fertilizers for tree crops, sustainable field management, crop productivity and fruit quality are also included in this review, under the light of the most important and recent research data existing in the literature, with the aim to provide recommendations and future directions for organic fertilizers by tree growers.
Theocharis Chatzistathis; Victor Kavvadias; Thomas Sotiropoulos; Ioannis Papadakis. Organic Fertilization and Tree Orchards. Agriculture 2021, 11, 692 .
AMA StyleTheocharis Chatzistathis, Victor Kavvadias, Thomas Sotiropoulos, Ioannis Papadakis. Organic Fertilization and Tree Orchards. Agriculture. 2021; 11 (8):692.
Chicago/Turabian StyleTheocharis Chatzistathis; Victor Kavvadias; Thomas Sotiropoulos; Ioannis Papadakis. 2021. "Organic Fertilization and Tree Orchards." Agriculture 11, no. 8: 692.
Under the current and future climate crisis, a significant rise in soil salinity will likely affect vine productivity in several Mediterranean regions. During the present research, the rootstock effects on salinity tolerance of Merlot and Cabernet Franc grapevine cultivars were studied. In a pot hydroponic culture, own-rooted Merlot and Cabernet Franc grapevine cultivars or grafted onto the rootstocks 1103 P and 101-14 Mgt were drip-irrigated with saline water. A completely randomized 3 × 2 × 2 factorial experiment was designed with two vine rootstocks or own-rooted vines, two scion cultivars, and 100 mM NaCl salinity or control treatments, with six replications. A significant effect of scion cultivar, rootstock, and salinity was observed for most of the measured parameters. At the end of salinity stress period, leaf, shoot, root, and trunk nutrient concentrations were measured. Salinity stress increased Chloride (Cl) and Sodium (Na) concentrations in all parts of the vines and decreased leaf concentrations of Potassium (K), Calcium (Ca), Magnesium (Mg), Nitrogen (N), and Iron (Fe). In contrast, salinity stress increased leaf Boron (B) concentrations, whereas that of Manganese (Mn) remained unaffected. Leaf chlorophyll concentration decreased from 42% to 40% after thirty and sixty days of salt treatment, respectively. A similar trend was observed for the CCM-200 relative chlorophyll content. Salinity significantly decreased steam water potential (Ws), net CO2 assimilation rate (A), and stomatal conductance (gs) in all cases of grafted or own-rooted vines. Sixty days after the beginning of salt treatment, total Phenolics and PSII maximum quantum yield (Fv/Fm) decreased significantly. The rootstock 1103 P seems to be a better excluder for Na and Cl and more tolerant to salinity compared to 101-14 Mgt rootstock.
Kleopatra-Eleni Nikolaou; Theocharis Chatzistathis; Serafeim Theocharis; Anagnostis Argiriou; Stefanos Koundouras; Elefteria Zioziou. Effects of Salinity and Rootstock on Nutrient Element Concentrations and Physiology in Own-Rooted or Grafted to 1103 P and 101-14 Mgt Rootstocks of Merlot and Cabernet Franc Grapevine Cultivars under Climate Change. Sustainability 2021, 13, 2477 .
AMA StyleKleopatra-Eleni Nikolaou, Theocharis Chatzistathis, Serafeim Theocharis, Anagnostis Argiriou, Stefanos Koundouras, Elefteria Zioziou. Effects of Salinity and Rootstock on Nutrient Element Concentrations and Physiology in Own-Rooted or Grafted to 1103 P and 101-14 Mgt Rootstocks of Merlot and Cabernet Franc Grapevine Cultivars under Climate Change. Sustainability. 2021; 13 (5):2477.
Chicago/Turabian StyleKleopatra-Eleni Nikolaou; Theocharis Chatzistathis; Serafeim Theocharis; Anagnostis Argiriou; Stefanos Koundouras; Elefteria Zioziou. 2021. "Effects of Salinity and Rootstock on Nutrient Element Concentrations and Physiology in Own-Rooted or Grafted to 1103 P and 101-14 Mgt Rootstocks of Merlot and Cabernet Franc Grapevine Cultivars under Climate Change." Sustainability 13, no. 5: 2477.
Under high organic matter content, even under low extractable soil P concentrations, sufficient or over-sufficient foliar P levels may be found. This multi-year study aimed at examining the effects of organic matter content and irrigation management on (a) soil fertility, (b) P-cycle related soil enzymes (acid and alkaline phosphatase, pyrophosphatase) and (c) foliar nutrient concentrations. Irrigated and non-irrigated groves of fully productive trees of the cultivar “Chondrolia Chalkidikis” with low organic matter (LOM < 1.5%), medium organic matter (1.5% < MOM < 2.5%) and high organic matter (HOM > 2.5%) were selected for the experimentation. It was hypothesized that olive groves receiving high inorganic fertilization and irrigation inputs (usually with medium to relatively low organic matter content) would show higher soil and foliar P concentrations compared to the non-irrigated groves with higher organic matter content receiving manure applications. Most of the soil variables (including the three enzymes’ activities) were affected by differences in organic matter content. However, organic matter content did not show a significant influence on foliar nutrient concentrations. Olive trees, especially those cultivated in soils with high organic matter content (receiving organic fertilization), can over-satisfy their P nutritional needs, even though soil analyses show low soil extractable P concentrations, probably due to the high enzymatic activity of acid and alkaline phosphatases. The practical conclusion of this study is that P fertilizer recommendations should be primarily based on foliar P rather than on extractable soil P.
Niki Christopoulou; Theocharis Chatzistathis; Efimia Papatheodorou; Vassilis Aschonitis; Nikolaos Monokrousos. The Crucial Role of Soil Organic Matter in Satisfying the Phosphorus Requirements of Olive Trees (Olea europaea L.). Agriculture 2021, 11, 111 .
AMA StyleNiki Christopoulou, Theocharis Chatzistathis, Efimia Papatheodorou, Vassilis Aschonitis, Nikolaos Monokrousos. The Crucial Role of Soil Organic Matter in Satisfying the Phosphorus Requirements of Olive Trees (Olea europaea L.). Agriculture. 2021; 11 (2):111.
Chicago/Turabian StyleNiki Christopoulou; Theocharis Chatzistathis; Efimia Papatheodorou; Vassilis Aschonitis; Nikolaos Monokrousos. 2021. "The Crucial Role of Soil Organic Matter in Satisfying the Phosphorus Requirements of Olive Trees (Olea europaea L.)." Agriculture 11, no. 2: 111.
One of the most important issues for modern agriculture is how to decrease fertilization rates and enhance the sustainability of crops, without decreasing yields. Two inorganic (zeolite—zeo; vermiculite—ver) amendments and their mixtures with an organic soil amendment (goat manure) (i.e., zeo + ver, manure + ver, manure + zeo) were tested, and compared to the application of a controlled release fertilizer (CRF), in order to investigate if they were able to satisfy the nutritional needs of Solanum lycopersicon L. plants. For this purpose, a 112-day pot experiment was performed. After zeo and manure application, exchangeable K was increased from 16.5 times to 37.5 times. At the end of the experiment, total plant biomass was significantly higher in the CRF treatment, compared to the ver treatments (ver, ver + manure). Leaf K concentration was significantly higher in the zeo treatment (5.93% dw), compared to those determined in the CRF, ver, and ver + manure. In contrast, significantly higher foliar N was found in the CRF (4.83% dw) and zeo + ver (4.24% dw) treatments, compared to manure + ver. Finally, photosystem II (PSII) activity was significantly higher in ver, and this was ascribed to the optimum foliar Mn found in this treatment (138 mg kg−1 dw). It is expected that these data will provide a thorough insight towards decreasing chemical fertilization inputs and enhancing the sustainability of Solanum lycopersicon L. crop.
Theocharis Chatzistathis; Vasileios Tzanakakis; Anastasia Giannakoula; Polyxeni Psoma. Inorganic and Organic Amendments Affect Soil Fertility, Nutrition, Photosystem II Activity, and Fruit Weight and May Enhance the Sustainability of Solanum lycopersicon L. (cv. ‘Mountain Fresh’) Crop. Sustainability 2020, 12, 9028 .
AMA StyleTheocharis Chatzistathis, Vasileios Tzanakakis, Anastasia Giannakoula, Polyxeni Psoma. Inorganic and Organic Amendments Affect Soil Fertility, Nutrition, Photosystem II Activity, and Fruit Weight and May Enhance the Sustainability of Solanum lycopersicon L. (cv. ‘Mountain Fresh’) Crop. Sustainability. 2020; 12 (21):9028.
Chicago/Turabian StyleTheocharis Chatzistathis; Vasileios Tzanakakis; Anastasia Giannakoula; Polyxeni Psoma. 2020. "Inorganic and Organic Amendments Affect Soil Fertility, Nutrition, Photosystem II Activity, and Fruit Weight and May Enhance the Sustainability of Solanum lycopersicon L. (cv. ‘Mountain Fresh’) Crop." Sustainability 12, no. 21: 9028.
The olive tree (Olea europaea L.) is an emblematic, long-living fruit tree species of profound economic and environmental importance. This study is a literature review of articles published during the last 10 years about the role of beneficial microbes [Arbuscular Mycorrhizal Fungi (AMF), Plant Growth Promoting Rhizobacteria (PGPR), Plant Growth Promoting Fungi (PGPF), and Endophytes] on olive tree plant growth and productivity, pathogen control, and alleviation from abiotic stress. The majority of the studies examined the AMF effect using mostly Rhizophagus irregularis and Glomus mosseae species. These AMF species stimulate the root growth improving the resistance of olive plants to environmental and transplantation stresses. Among the PGPR, the nitrogen-fixing bacteria Azospirillum sp. and potassium- and phosphorous-solubilizing Bacillus sp. species were studied extensively. These PGPR species were combined with proper cultural practices and improved considerably olive plant’s growth. The endophytic bacterial species Pseudomonas fluorescens and Bacillus sp., as well as the fungal species Trichoderma sp. were identified as the most effective biocontrol agents against olive tree diseases (e.g., Verticillium wilt, root rot, and anthracnose).
Georgios Bizos; Efimia M. Papatheodorou; Theocharis Chatzistathis; Nikoletta Ntalli; Vassilis G. Aschonitis; Nikolaos Monokrousos. The Role of Microbial Inoculants on Plant Protection, Growth Stimulation, and Crop Productivity of the Olive Tree (Olea europea L.). Plants 2020, 9, 743 .
AMA StyleGeorgios Bizos, Efimia M. Papatheodorou, Theocharis Chatzistathis, Nikoletta Ntalli, Vassilis G. Aschonitis, Nikolaos Monokrousos. The Role of Microbial Inoculants on Plant Protection, Growth Stimulation, and Crop Productivity of the Olive Tree (Olea europea L.). Plants. 2020; 9 (6):743.
Chicago/Turabian StyleGeorgios Bizos; Efimia M. Papatheodorou; Theocharis Chatzistathis; Nikoletta Ntalli; Vassilis G. Aschonitis; Nikolaos Monokrousos. 2020. "The Role of Microbial Inoculants on Plant Protection, Growth Stimulation, and Crop Productivity of the Olive Tree (Olea europea L.)." Plants 9, no. 6: 743.
In the current paper we assess different machine learning (ML) models and hybrid geostatistical methods in the prediction of soil pH using digital elevation model derivates (environmental covariates) and co-located soil parameters (soil covariates). The study was located in the area of Grevena, Greece, where 266 disturbed soil samples were collected from randomly selected locations and analyzed in the laboratory of the Soil and Water Resources Institute. The different models that were assessed were random forests (RF), random forests kriging (RFK), gradient boosting (GB), gradient boosting kriging (GBK), neural networks (NN), and neural networks kriging (NNK) and finally, multiple linear regression (MLR), ordinary kriging (OK), and regression kriging (RK) that although they are not ML models, they were used for comparison reasons. Both the GB and RF models presented the best results in the study, with NN a close second. The introduction of OK to the ML models’ residuals did not have a major impact. Classical geostatistical or hybrid geostatistical methods without ML (OK, MLR, and RK) exhibited worse prediction accuracy compared to the models that included ML. Furthermore, different implementations (methods and packages) of the same ML models were also assessed. Regarding RF and GB, the different implementations that were applied (ranger-ranger, randomForest-rf, xgboost-xgbTree, xgboost-xgbDART) led to similar results, whereas in NN, the differences between the implementations used (nnet-nnet and nnet-avNNet) were more distinct. Finally, ML models tuned through a random search optimization method were compared with the same ML models with their default values. The results showed that the predictions were improved by the optimization process only where the ML algorithms demanded a large number of hyperparameters that needed tuning and there was a significant difference between the default values and the optimized ones, like in the case of GB and NN, but not in RF. In general, the current study concluded that although RF and GB presented approximately the same prediction accuracy, RF had more consistent results, regardless of different packages, different hyperparameter selection methods, or even the inclusion of OK in the ML models’ residuals.
Panagiotis Tziachris; Vassilis Aschonitis; Theocharis Chatzistathis; Maria Papadopoulou; Ioannis (John) D. Doukas. Comparing Machine Learning Models and Hybrid Geostatistical Methods Using Environmental and Soil Covariates for Soil pH Prediction. ISPRS International Journal of Geo-Information 2020, 9, 276 .
AMA StylePanagiotis Tziachris, Vassilis Aschonitis, Theocharis Chatzistathis, Maria Papadopoulou, Ioannis (John) D. Doukas. Comparing Machine Learning Models and Hybrid Geostatistical Methods Using Environmental and Soil Covariates for Soil pH Prediction. ISPRS International Journal of Geo-Information. 2020; 9 (4):276.
Chicago/Turabian StylePanagiotis Tziachris; Vassilis Aschonitis; Theocharis Chatzistathis; Maria Papadopoulou; Ioannis (John) D. Doukas. 2020. "Comparing Machine Learning Models and Hybrid Geostatistical Methods Using Environmental and Soil Covariates for Soil pH Prediction." ISPRS International Journal of Geo-Information 9, no. 4: 276.