**3. Results and discussion**

system is reduced. In cereals, the processes involved in senescence are important because they occur during grain filling, and evidence suggests that early senescence may be yield-limiting [5]. Wheat genotypes vary in the timing of senescence initiation and also in the subsequent rate of leaf senescence. In wheat, the senescence rate was also found to be related to the yield under drought conditions [6, 7]. The quest of the causes of differences in leaf photosynthetic rate among interspecies and/or intraspecies of crops may be one of the important strategies of crop engineering [8]. In all these studies, leaf senescence was evaluated visually. Since senescence corresponds to yellowing due to chlorophyll loss [5], the identification of senescent parts of the leaf is quite easy. In this work, we used an alternative method for the evaluation of the leaf senescence based on numerical analysis of image. In addition, we study the efficiency of using the flag leaf senescence as tools

*Plant Science - Structure, Anatomy and Physiology in Plants Cultured in Vivo and in Vitro*

for select adapted durum wheat genotypes under semi-arid 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

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

**Genotype Origin Genotype Origin** Bousselem ICARDA/CIMMYT Altar84 CIMMYT Hoggar Spain Dukem CIMMYT Oued Zenati Algeria Kucuk CIMMYT Polonicum Algeria Mexicali75 CIMMYT Waha ICARDA/CIMMYT Sooty CIMMYT

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>

E, 36°8'N, 958 m above sea level) genotypes were

.

**2. Materials and methods**

INRAA, Setif, Algeria (5°20<sup>0</sup>

**2.1 Plant material and growth conditions**

**2.2 Agronomical and physiological measurements**

the relationships between the traits measured.

**Table 1.**

**82**

*Name and origin of tested genotypes.*

The ANOVA analysis demonstrates significant effect of genotypes and years on senescence parameters and GY. Based on the means comparison, the values of mean grain yield (2009–2013) varied from 37.84 q/ha for Oued Zenati to 44.7 q/ha for


#### **Table 2.**

*ANOVA analysis and means comparison of grain yield over four cropping seasons.*


#### **Table 3.**

*Ranking of tested genotypes based on the grain yield.*

Altar84 with general mean of 42.71 q/ha. Based on the climatic data, the defavorable cropping season is the first one (2009–2010) with mean grain yield equal 27.29 q/ha; during this season, the grain yield varied between 22.0 q/ha for Dukem to 31.93 q/ha for Mexicali**75**. In addition, the best season is 2010–2011 with mean grain yield of 58.49 q/ha, the highest grain yield registered by the genotype Waha (64.63 q/ha) (**Table 2**). The ranking based on the mean grain yield demonstrates that the genotypes Mexicali**75**, Hoggar, and Sooty (**Table 3**) have the best ranking with low values of standard deviation in the changement of ranking over years (1.48, 1.48, and 1.79, respectively); the mean grain yield of these genotypes varied between 44.69, 44.29, and 43.42 q/ha, respectively. A highly significant genotype and years effects was noted for Sa% (average senescence) and the date of midsenescence (Σ50s) (**Table 4**); the mean values over years of Sa% varied between 47.91% for the genotype Oued Zenati and 59.45% for Waha. For the last parameter


(Sa%), the genotypes with lowest values are the preferable and adapted genotype. However, the genotypes with highest values for the parameter mid-senescence (Σ50s) are the most tolerant and adapted genotypes; the mean values over years of mid-senescence varied between 464.14°C for the genotype Mexicali**<sup>75</sup>** and 309.66°C for the genotype Oued Zenati. The total mean rankings based on the senescence parameters demonstrate that the genotypes Mexicali**75**, Hoggar, and Sooty are the best genotypes under these conditions (**Table 5**). Our study showed significant correlation between grain yield and the parameter mid-senescence (Σ50s) (r = 0.91\*). Over 50 years ago, it was realized that the diversity in yield for most crops is mainly a consequence of variation in the duration, rather than the rate of photosynthetic activity [10], and so, delayed leaf senescence (i.e., stay-green) has long been considered to be a desirable trait in cereal breeding. Total flag leaf photosynthesis, chlorophyll content, the onset of senescence (at low nitrogen availability), and green leaf duration have all been found to be positively correlated with

**Genotype Ranking based on Senescence parameters Mean**

*Leaf Senescence in Wheat: A Drought Tolerance Measure*

*DOI: http://dx.doi.org/10.5772/intechopen.89500*

**Sa% Σ50S Sa% Σ50S Sa% Σ50S Sa% Σ50S**

*Ranking of tested genotypes based on the senescence parameters.*

**ranking**

**2009/2010 2010/2011 2011/2012 2012/2013 Sa% Σ50S Sa% Σ50S**

10 8 1 10 1 10 3 9 2 10 5 3.49 0.80

Altar84 2 385955774 4 2.45 1.74 Sooty 5 6 5 3 4 3 8 10 5 5 3 1.47 2.58 Polonicum 7 5 2 8 3 8 6 8 3 9 5 1.94 1.36 Waha 9 10 9 6 10 6 10 3 10 8 8 0.49 2.23 Dukem 3 7 10 7577186 7 2.42 2.40 Mexicali**75** 1 1 4 2 2 2 1 6 1 1 1 1.10 1.85 Kucuk 8 9 3 1 7 1 9 4 9 2 4 2.23 2.93 Hoggar 4 4 7 4 6 4 4 5 4 3 2 1.26 0.63 Bousselem 6 2 6 9 8 9 2 2 6 7 6 1.96 3.29

**Total mean ranking**

**SD of ranking**

The results of this study demonstrate that the genotypes with highest values for the parameter mid-senescence (Σ50s) are the most tolerant and adapted genotypes. Based on the mean grain yield ranking, the genotypes Mexicali**75**, Hoggar, and Sooty have the best grain yield. In addition, the screening based on the senescence parameters showed that the genotypes Mexicali**75**, Hoggar, and Sooty are the preferable and adapted genotype. The combination between the rankings based on the GY and senescence parameters demonstrate that the genotypes Mexicali**75**, Hoggar,

and Sooty are the best and recommended genotypes under this condition.

wheat grain yield [11].

**4. Conclusion**

**85**

Oued Zenati

**Table 5.**

#### **Table 4.**

*ANOVA analysis and means comparison of senescence parameters over four cropping seasons.*


*Leaf Senescence in Wheat: A Drought Tolerance Measure DOI: http://dx.doi.org/10.5772/intechopen.89500*

#### **Table 5.**

Altar84 with general mean of 42.71 q/ha. Based on the climatic data, the defavorable

27.29 q/ha; during this season, the grain yield varied between 22.0 q/ha for Dukem to 31.93 q/ha for Mexicali**75**. In addition, the best season is 2010–2011 with mean grain yield of 58.49 q/ha, the highest grain yield registered by the genotype Waha (64.63 q/ha) (**Table 2**). The ranking based on the mean grain yield demonstrates that the genotypes Mexicali**75**, Hoggar, and Sooty (**Table 3**) have the best ranking with low values of standard deviation in the changement of ranking over years (1.48, 1.48, and 1.79, respectively); the mean grain yield of these genotypes varied between 44.69, 44.29, and 43.42 q/ha, respectively. A highly significant genotype and years effects was noted for Sa% (average senescence) and the date of midsenescence (Σ50s) (**Table 4**); the mean values over years of Sa% varied between 47.91% for the genotype Oued Zenati and 59.45% for Waha. For the last parameter

**Genotype 2009/2010 2010/2011 2011/2012 2012/2013 Mean over all**

48.56 (e)

63.26 (ab)

56.69 (cd)

55.85 (cd)

67.76 (a)

57.64 (cd)

55.63 (d)

60.83 (bcd)

60.12 (bcd)

61.11 (bc)

58.74 (a)

\*\*\* \*\*\* \*\*\* \*\*\* \*\*\*

Min 35.31 269.77 44.51 356.78 48.56 350.01 47.35 190.54 47.91 309.66 Max 49.3 338.85 63.44 625.25 67.76 628.48 58.51 289.63 59.45 464.14

LSD **5%** 1.24 5.34 4.12 16.23 5.28 13.33 1.33 26 1.68 8.16 Years effect \*\*\* \*\*\* \*\*\* \*\*\* \*\*\*

Oued Zenati

Altar84 38.96

Sooty 42.57

Polonicum 43.24

Waha 48.07

Dukem 40.31

Mexicali 75 35.31

Kucuk 45.19

Hoggar 40.95

Bousselem 42.8

Mean 42.67

Genotype effect

*\*\*\* P < 0.001*

**Table 4.**

**84**

49.30 (a)

(e)

(cd)

(c)

(a)

(e)

(f)

(b)

(de)

(cd)

(d)

290.9 (d)

333.54 (a)

305.17 (c)

312.82 (b)

269.77 (e)

298.59 (c)

338.85 (a)

286.63 (d)

316.92 (b)

334.46 (a)

308.76 (b)

44.51 (d)

58.94 (ab)

55.5 (bc)

51.53 (c)

63.44 (a)

60.26 (ab)

54.18 (bc)

54.12 (bc)

57.53 (bc)

56.79 (bc)

55.68 (b)

356.78 (f)

593.49 (cb)

594.93 (cb)

479.54 (e)

578.72 (c)

515.37 (d)

612.43 (ab)

625.25 (a)

594.25 (cb)

470.64 (e)

542.14 (a)

LSD **5%** 1.01 5.20 1.01 5.20 1.01 5.20 1.01 5.20

*ANOVA analysis and means comparison of senescence parameters over four cropping seasons.*

**Sa % Σ50S Sa % Σ50S Sa % Σ50S Sa % Σ50S Sa % Σ50S**

350.01 (g)

596.72 (bc)

598.16 (b)

489.44 (e)

584.29 (c)

518.60 (d)

615.66 (a)

628.48 (a)

597.48 (bc)

445.87 (f)

542.47 (a)

49.26 (e)

> 49.9 (e)

56.82 (b)

51.25 (d)

58.51 (a)

53.68 (c)

47.35 (f)

57.20 (ab)

49.36 (e)

47.84 (f)

52.12 (c)

240.95 (cd)

283.68 (ab)

196.90 (ef)

247.20 (c)

239.23 (cd)

217.24 (de)

289.63 (a)

190.54 (f)

260.77 (bc)

281.84 (ab)

244.80 (c)

**seasons**

309.66 (g)

451.86 (b)

423.79 (e)

382.25 (f)

418.00 (e)

387.45 (f)

464.14 (a)

432.73 (d)

442.35 (c)

383.20 (f)

52.3 409.54

47.91 (e)

52.77 (bc)

52.89 (bc)

50.47 (d)

59.45 (a)

52.97 (bc)

48.12 (e)

54.33 (b)

51.99 (cd)

52.13 (cd)

cropping season is the first one (2009–2010) with mean grain yield equal

*Plant Science - Structure, Anatomy and Physiology in Plants Cultured in Vivo and in Vitro*

*Ranking of tested genotypes based on the senescence parameters.*

(Sa%), the genotypes with lowest values are the preferable and adapted genotype. However, the genotypes with highest values for the parameter mid-senescence (Σ50s) are the most tolerant and adapted genotypes; the mean values over years of mid-senescence varied between 464.14°C for the genotype Mexicali**<sup>75</sup>** and 309.66°C for the genotype Oued Zenati. The total mean rankings based on the senescence parameters demonstrate that the genotypes Mexicali**75**, Hoggar, and Sooty are the best genotypes under these conditions (**Table 5**). Our study showed significant correlation between grain yield and the parameter mid-senescence (Σ50s) (r = 0.91\*). Over 50 years ago, it was realized that the diversity in yield for most crops is mainly a consequence of variation in the duration, rather than the rate of photosynthetic activity [10], and so, delayed leaf senescence (i.e., stay-green) has long been considered to be a desirable trait in cereal breeding. Total flag leaf photosynthesis, chlorophyll content, the onset of senescence (at low nitrogen availability), and green leaf duration have all been found to be positively correlated with wheat grain yield [11].
