Phyllotaxis and handedness in date palm (Phoenix dactylifera L.)

The present study had as objectives to measure the palm leaf divergence angle in the field, to determine the frequency of trees and offshoots showing clockwise and counterclockwise phyllotaxis, to establish the relationship between phyllotaxis of the mother tree and that of its offshoots, and, finally, to determine the effect of the divergence angle value on production. Materials and methods. The vegetal material was composed of four Moroccan cultivars of Phoenix dactylifera L. Observations were conducted in the south of Morocco on 20 trees per cultivar and four offshoots per tree. The divergence angle was measured on adult trees whereas phyllotaxic direction (clockwise or counterclockwise) was noted for both offshoots and adult trees. Results and discussion. This study showed that the phyllotaxic direction of the offshoots presents a clockwise or counterclockwise phyllotaxis independently of the mother plant. The divergence angle varied depending on the cultivar. This character is an interesting criterion, both for the selection of the best adapted cultivars for the marginal date palm growing regions, and for an optimal production

Variations in physicochemical and microbiological characteristics of ‘Mejhoul’ dates (Phoenix dactylifera L.) from Morocco and new countries of its expansion

Mejhoul’ date cultivar originated from Morocco and largely spread around the world. It is of high commercial value and is considered to be one of the best-exported dates concerning its fruit quality and size in comparison with other cultivars. This study aims to investigate variations within the physicochemical and microbiological characteristics of ‘Mejhoul’ dates sampled from its original growing areas in Morocco and other countries, where the cultivar is expanded in the recent years. Dates samples were collected from the most important production areas of the ‘Mejhoul’ cultivar in Morocco (Figuig, Bouanane, Boudnib, Difat Ziz, Rissani and Zagora) and the United States of America, Kingdom of Saudi Arabia, Jordan and Palestine. Variance analysis of pH, moisture, ash and sugar content show a significant difference (p < 0.05) within ‘Mejhoul’ cultivar samples. Statistical analysis (Principal Component Analysis “PCA”) allows the classification of samples into three groups. The first group holds ‘Mejhoul’ samples from Morocco, including Figuig, Boudnib and Difat Ziz, characterized by high water content and high density of TVC and Yeasts. The second group is composed of all international samples (Palestine, Jordan, USA and KSA) in addition to samples from Rissani (Morocco), presents reverse characteristics compared to the first group. The third group includes ‘Mejhoul’ from Bouanane and Zagora (Morocco). Despite the availability of favorable conditions, making Morocco an ideal area for ‘Mejhoul’ production. However export of this date cultivar remains limited from Morocco due to uncontrolled production techniques and environmental factors

Effect of harvesting and post-harvest practices on the microbiological quality of dates fruits (Phoenix dactylifera L.)

In Morocco, many dates varieties are produced and marketed, including local and imported dates, mainly Deglet Nour variety. The present study aimed to evaluate microbiological contamination on ten varieties of dates from four different production areas in Morocco, from the date market of Marrakech, and from the imported Deglet Nour variety, and to show effects of harvesting and post-harvest practices on the microbiological quality of dates. Physicochemical data presented that the pH of studied varieties varies between 5 and 6 and water activity from 0.28 to 0.62. Microbiological analysis displayed that samples from Tata region presented the highest microbial spoilage with Total Viable Counts (TVC) ranging from 4.2 log CFU.g-1 to 2.6 log CFU.g-1 and yeast/moulds reaching 2.99 log CFU.g-1. Deglet Nour dates imported from Algeria, and Tunisia were less contaminated (TVC <1.0 log CFU.g-1, yeasts/moulds <1.0 log CFU.g-1). Coliforms, Bacillus sp. and Staphylococcus were not found in any sample. Results revealed that some varieties produced and marketed in Morocco are affected by microbial spoilage, which can be assigned to uncontrolled dates processes of harvesting and post-harvesting practices

Calibration of Thermal Dissipation Probes for Date Palm (Phoenix dactylifera L.)

The quantification of water flow through the stem is vital for date palm (Phoenix dactylifera L.) to promote a good water stress management. The thermal dissipation probe (TDP) method developed by Granier is widely used to evaluate transpiration of forest trees; however, there are contradictory reports regarding its reliability. Considerable errors in estimated sap flux density, which might be due to a lack ofspecies-specific calibrations. The TDP method uses a mathematical model that is based on an empirical equation to estimate sap flux density, which is claimed to be applicable to all tree species, independently of wood structure and anatomy. At the laboratory, we compared the rate of water uptake by cut stems with sap flux estimates derived from the TDP method to assess the validity of the method.Our calibration results were considerably different compared to the Granier’s original equation. Moreover, sap flux density was overestimated by 18.2 ± 0.5% when the original calibration parameters of Granierare employed. However, using new calibration parameters improved the accuracy of sap flow measurements. Our results indicated that it is not appropriate to use a general equation for different species. Therefore, previous estimations of date palm’s water requirement through thermal dissipation probes should be revised