English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In Tunisia (36.5oN, 10.2oE, Alt.10 m), rainfall isthe major factor govering olive production. Annual and seasonal falls arevariable following years and regions, making yields of olive treesfluctuating consistently. Irrigationwas applied since the 70th in the intensive olive orchards toimprove and stabilize olive production. This study aimed to determine the cropwater needs of olive orchards and the rainfall frequencies at which they arecovered following age and site of olive production. For this purpose, therainfall distribution functions were established for different cities ofTunisia (Tunis, Bizerte, Beja, Nabeul, Sidi Bouzid, Gabes and Sousse). For allsites and growing periods, the reference evapotranspiration (ET0)was computed by using several methods. Their performance against thePM-ET0 (Penman-Monteith) estimates wasevaluated graphically and statistically for a better adaptation them to theexisting environmental conditions, particularly when dataare missing to compute ET0-PM. Results show that ET0 estimates strongly correlate with ET0-PM with r values of up to0.88. Particularly, the methods of Turc and Ivanov appropriately predict the ET0-PMin all climatic regions of Tunisia, constituing an appropriate alternative fordetermining ET0 when data are missing to compute ET0-PM.However, although the Turc method performs well with all climatic zones ofTunisia, the Ivanov method appears to be more appropriate to the northern areas(Beja and Bizerte), though a poorer agreement was found when using the Eaglemanmethod. Estimates of ET0 by using the Hargreave-Samani (HS) formulafor the east-southern area (Gabes, arid climate) show satisfactory agreementwith ET0-PM estimates. It appears also that at a given site, themost appropriate method for ET0 estimation at annual scale may bedifferent from that giving the best value of ET0 when consideringthe growing stages of the olive tree, for example, the method of Turc, althoughit was appropriate when estimating the annual ET0 value for Sousse,it wasn’t adequate at seasonal scale. In opposite, although the method of BC issuitable for stages 1, 2, 4 and 5 at Sousse, the appropriate method for theoverall cycle is that of Turc. This indicates that there is no weather-basedevapotranspiration equation that can be expected to predict evapotranspirationperfectly under every climatic situation due to simplification in formulationand errors in data measurement. However, we can say that when data are missing,ET0 can be estimated with a specific formula; that of Turc can beappropriately used for Tunis, Sidi Bouzid, Sousse and Beja at annual scaledespite of their appartenance to different climatic regions, while the methodof Ivanov is quite valuable for Bizerte and Nabeul. Results show also thatvalues of P-ETc recorded during the irrigation period are negative even foryoung plantations, with lowest and highest deficits observed at Beja and Gabescities, respectively. The driestperiod is that of July-August for all sites with F values exceeding 0.9 in mostcases. Only 10% of water needs are supplied by rainfall during this period offruit development. Therefore, irrigation is needed all time for adult treeseven at the rainiest locations. For young plantations, irrigation becomesnecessary beginning from the second period of tree development, i.e. April-Junefor Bizerte, Beja, Nabeul and Tunis and since the early spring period for bothyoung and old plants for Gabes and Sidi-Bouzid. It appears from this analyzebased on the seasonal rainfall frequencies and water needs computed with thePM-method, that there is a need for irrigating olive plantations aging more than 5years in most case studies and especially when olive is cultivated in thewestern areas of Tunisia. Results indicate also that the use of no adequatemethod to estimate ET0 allowed overestimating or underestimating ofirrigation water needs. So it is desirable to have for Tunisia a method thatestimates ET consistently well and future research is needed to reconcile whichshould be the standard method of calculating the change in the crop coefficientover time. However, despite a quite good performance of the PM-equation in mostapplications, particularly when it is used for irrigation scheduling purposes,some problems may appear because of lack of local information on Kc-values anddetermination of the effective rainfall. Additional research is needed ondeveloping crop coefficients that use the Penman-Monteith equation whencalculating ET. In conclusion we can say that on the basisof the results produced, we can decide for each region and growing period ifcomplementary irrigation is needed or not. Indicative amounts are given foreach case study.

american journal of plant sciences

Rainfall Distribution Functions for Irrigation Scheduling: Calculation Procedures Following Site of Olive (&amp;lt;i&amp;gt;Olea europaea&amp;lt;/i&amp;gt; L.) Cultivation and Growing Periods