**2. Materials and methods**

## **2.1 Plant material and growth conditions**

A set of 10 genotypes of durum wheat (*Triticum durum* Desf.) (**Table 1**) were planted during four cropping seasons (2009–2013), in the experimental fields of INRAA, Setif, Algeria (5°20<sup>0</sup> E, 36°8'N, 958 m above sea level) genotypes were grown in randomized block design with four replicates. Plots were 5 m � 6 rows with 0.20 m row spacing, and sowing density was adjusted to 300 g m�<sup>2</sup> .

### **2.2 Agronomical and physiological measurements**

Grain yield (GY) is determined from sub-samples taken from harvested grains of each plot. Leaf senescence (S) was evaluated by numerical image analysis (NIA) according to Hafsi et al. [9]. Leaves were photographed on black surface, between 11:00 and 12:00 solar time with a color digital camera (Canon, Power Shot A460, AiAF, China). Images were analyzed using IPP (Image Pro Plus, Version 4, Media Cybernetics, Silver Spring, MA, USA) software. Senescence was expressed as the ratio of senesced area to total leaf area (in %). Measurements were carried out 10 times between flowering and the end of senescence on three flag leaves for each genotype. Ten dates of assessments were expressed in sums of temperatures after flowering (Σt1 � Σt10) and the corresponding senescence values (S1 � S10). In addition, the date of mid-senescence (Σ50) was evaluated from the experimental curves S = f (Σt) as the sum of temperature corresponding to an S value of 50%. Data were analyzed using Costat; the analysis of variance was performed for senescence parameters and grain yield. Linear correlation analysis was used to determine the relationships between the traits measured.


#### **Table 1.** *Name and origin of tested genotypes.*
