Isa Keramatlou; Saeid Navabpour; Khalil Zainilnejad; Elahe Tavakol; Seyyed Mehdi Hosseini Mazinani
Abstract
Introduction
Low temperature is one of the major abiotic stresses which can cause a significant reduction in olive growth and productivity mainly at late autumn, winter and early spring. Although olive is moderately freezing tolerant, temperatures below a certain threshold -7oC can damage the plant, ...
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Introduction
Low temperature is one of the major abiotic stresses which can cause a significant reduction in olive growth and productivity mainly at late autumn, winter and early spring. Although olive is moderately freezing tolerant, temperatures below a certain threshold -7oC can damage the plant, while at -12oC damage may be serious enough to threaten the life of the tree. Different cultivars of olives have diverse reactions to cold stress and so, the selection of cold resistant cultivars is the most effective method to avoid frost damages. First step to achieve this goal, is indentifying tolerant cultivar and genotypes in olive area growing. Due to extensive and high freezing damage in November 2016, the objective of the present study was to evaluate morphological characteristics and selection of single -tolerant cold trees.
Materials and Methods
The present study was carried out in some cold tolerant olives after freezing event in December 2016 in Eastern region of Golestan province of Iran. After freezing stress Healthy olive trees were identified in tow major olive cultivation regions and then were evaluated in four stages. Thus, this study included: 1- Meteorological data analysis, 2- Evaluation of freezing stress symptoms in olive orchards and identification of single tolerant trees, 3-stugy of single tolerant cold trees in 4 stages. For each genotype, studies on morphological traits (Tree age, location altitude, dip direction and its percentage, previous yield, tree height, canopy height, average of canopy diameter, canopy volume, canopy surface area, trunk perimeter, trunk diameter, trunk cross section area, length of internodes, growth habit, canopy density, canopy defoliation, barksplit ranging, flowering and fruit set) based on CFC / IOOC / 03 and Lodolini et al. (2016) results.
Results and Discussion
History of cold climate in the last two decades showed freezing event several times cause damage to olive orchards. The last freezing stress occurred with the entrance of the cold air to the Golestan province and a sudden drop in temperature to less than 0 degrees Celsius and stability of these conditions for 5-days in the late of November, 2016. The temperature drops below 0 ° C began on November 23 and lasts for 4-days. However, the main damage to the olive orchards is on November 25, when temperature is - 7 ° C. The minimum temperature recorded in the studied regions in November 25, Maravehtapeh, Gonbad, Kalaleh and Minoudasht are -14.2, -12.7, -12.3 and -8.5 ° C, respectively. Symptoms of freezing damage on olive tree can range from shoot tip burns and defoliation up to bark split on branches or trunk. After 4 stages visiting olive orchards, Finally, from 218 primary individual trees, 58 trees were introduced for further evaluation. Location altitude (meters above sea level) of the idividual trees are 81-411 in the CTO-17 and CTO-5 genotypes, respectively. Generally, 93% of all trees identified in sloping land orchards, and the Percentage variation for this trait is 48. 99. Fruit production of selected olives before freezing event in 2016 showed except of 13 trees, 44 of olives was of 2-60 kg/tree. Tree height was 2-6.82 in CTO-35 and CTO-17 genotypes, respectively. However, average of canopy diameter in all genotypes was 2.68. Also, trunk diameter (TD) and trunk cross section area (TCSA) was maximum in CTO-29 and minimum in CTO-9. But the average of this trait was 17.13 cm. Variation between genotype in internode length changed between 1.05 in CTO-20 and 16.2 in the CTO-49. Reduction of internode spaces and shoot growth, even though the total node number is normal resistance of the olive tree to cold is reduced. Leaf defoliation is one of the most important symptoms of freezing event. The study of selected trees showed that 48 trees (83%) did not showed symptoms of leaf loss, and only 10 trees showed less than 50% leaf loss. Except for the CTO-54 genotype, which showed symptoms of bark spliting on one-year shoots, no evidence of bark spliting observed in other selected olives.
Conclusions
Although olive is the most cold-hardy of the subtropical fruit trees, some varieties can withstand low temperatures better than the other. Although temperatures at which olive trees can be damaged vary, depending on climatic conditions, temperatures at or below -7°C are often critical. The most important symptoms were leaf defoliation, bark split, and limb dieback. Finally, because of different influence of environmental factor in different regions, evaluation of location, yield and morphological traits showed some of cold tolerant olive in different region had a similar behavior, thus by supplementary molecular studies, it can be hoped that among recognized trees, cold resistant cultivars with acceptable yields were introduced.
Isa Karamatlou; Mohammad Mehdi Sharifani; Hossein Sabori
Abstract
Introduction: Persian walnut (Juglans regia L.) is a large, wind-pollinated, monoecious, dichogamous, long lived, perennial tree cultivated for its high quality wood and nuts throughout the temperate regions of the world. Growth model methodology has been widely used in the modeling of plant growth. ...
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Introduction: Persian walnut (Juglans regia L.) is a large, wind-pollinated, monoecious, dichogamous, long lived, perennial tree cultivated for its high quality wood and nuts throughout the temperate regions of the world. Growth model methodology has been widely used in the modeling of plant growth. Mathematical models are important tools to study the plant growth and agricultural systems. These models can be applied for decision-making anddesigning management procedures in horticulture. Through growth analysis, planning for planting systems, fertilization, pruning operations, harvest time as well as obtaining economical yield can be more accessible.Non-linear models are more difficult to specify and estimate than linear models. This research was aimed to studynon-linear regression models based on data obtained from fruit weight, length and width. Selecting the best models which explain that fruit inherent growth pattern of Persian walnut was a further goal of this study.
Materials and Methods: The experimental material comprising 14 Persian walnut genotypes propagated by seed collected from a walnut orchard in Golestan province, Minoudasht region, Iran, at latitude 37◦04’N; longitude 55◦32’E; altitude 1060 m, in a silt loam soil type. These genotypes were selected as a representative sampling of the many walnut genotypes available throughout the Northeastern Iran. The age range of walnut trees was 30 to 50 years. The annual mean temperature at the location is16.3◦C, with annual mean rainfall of 690 mm.The data used here is the average of walnut fresh fruit and measured withgram/millimeter/day in2011.According to the data distribution pattern, several equations have been proposed to describesigmoidal growth patterns. Here, we used double-sigmoid and logistic–monomolecular models to evaluate fruit growth based on fruit weight and4different regression models in cluding Richards, Gompertz, Logistic and Exponential growth for evaluation of fruit growth according to length and width(diameter) of fruit. Then to determine the most efficient model, different parameters of evaluation of model fitting were used. The best model was selected based on the highest value of R2and the lowest values for RMSE, AIC and BIC. The data were analyzed using SAS software (version 9.2) and Solver in Microsoft Excel.
Results and Discussion
Growth model based on fruit weight: According to the actual and estimated growth model based on fruit weight, double sigmoid function and logistic–monomolecular model showed a good prediction of fruit weight changes versus time data (days after full bloom). However, in general according to evaluation criteria, double sigmoid model was the best model to predict walnut fruit weight. Based on total fruit weight, fruit growth occurs at two stages: in the beginning of the growth phase, there is a slow growth for 30 days and then it is continued with a rapid growth until 60 days after full bloom. Thereafter, growth was again slow. At the beginning of the second phase of growth (70 to 85 days after full bloom), fruit growth increased again and then, walnut fruits started to ripe on the tree in summer, bright green husk (outer pericarp layer) changed to a yellowish color and the growth again decreased (130 days after full bloom).
Growth model based on fruit length and width measurements: Based on the actual and estimated growth pattern the Richard model describes the growth of fruit better than other models. The first phase lasted for about 15 days and the second phase of growth was very rapid and it lasted for 35 daysin most of genotypes. Then, fruit length and width did not change significantly until harvesting time. However, due to subtle changes of fruit length and width following fruit rapid growth stage, fruit weight is preferred for describing fruit growth of the Persian walnut. During the first phase of development, increasing size and weight are associated with the formation of new and larger cells and tissues. The second phase includes attainment of final nut form, and it is characterized mainly by chemical changes. These include changes in the shell as the cells become lignified and more important changes in kernel composition.
Conclusion: Based on thes tatistical testing and goodness of the fit, the best model between six nonlinear growth models, was double-sigmoid and Richard model swhich can be used to accurately predict fruit growth based on fruit weight, fruit lengt hand width, respectively.
