Study of drought tolerance indices in some bread and durum wheat cultivars

الملخص EN

Two experiments was conducted during 2013-2014 growing season at the Research Field belong to College of Agriculture, Salahaddin University, Erbil, Kurdistan Region, Iraq in order to identify drought-tolerant cultivars of bread and durum wheat.

The first experiment was conducted under rainfall (stress) conditions.

The second experiment was conducted under rainfall and irrigation (non-stress) conditions.

Ten bread wheat cultivars (Mexipak, Abu-graib 3, Adnania, Rabia, Ipa 99, Tammoz 2, Aras, Cham 4, Cham 6 and Adana 99) were planted on 15 Nov, 2013 using Randomized Complete Block Design with three replicates in each of experiment.

The same two experiments were applied to ten cultivars of durum wheat (Senator Capelii, Cocrate- C 71, Om-Rabi 5, Wahat AlIraq, Coseim N, Cham 3, Acsad 65, Ofanto, LD 357 E and Simeto).

Some drought tolerance indices were calculated for every cultivar using the corresponding non-stressed and stressed grain yield/plant in each replication.

Results showed a significant reduction in grain yield for bread and durum wheat cultivars under stress conditions.

Grain yield under rainfall (Ys) and irrigated (Yp) conditions was significantly and positively correlated with geometric mean productivity (GMP), harmonic mean (HM), mean productivity (MP), stress tolerance index (STI), modified stress tolerance index (K1STI, K2STI), and germination stress index (GSI) in bread wheat and with GMP, HM, MP, STI, yield index (YI), K1STI, K2STI, stress non stress production index (SNPI) and GSI in durum wheat revealed that these indices were more reliable to select high yielding bread and durum wheat cultivars under rainfall and irrigated conditions.

Screening drought tolerant cultivars using mean rank, standard deviation of ranks and rank sum (RS) distinguished cultivars, Mexipak, Abu-graib 3, Rabia Tammoz 2 and senator capelii, Wahat Al-Iraq, Cham 3 and Acsad 65 exhibited low standard deviation of rank, with least RS was the most drought tolerant bread wheat and durum wheat cultivars, respectively.

We can identify the cultivars with high and stable yield in both conditions which are (Mexipak [1], Abu-graib 3 [2] and (Senator Capelii [1], Coseim N [5], LD 357 E [9] in bread and durum wheat cultivars, respectively therefore, we can recommend these cultivars as superior cultivars for planting under conditions of drought stress.

Cluster analysis showed that the bread and durum cultivars, based on indices tended to group into three groups: tolerant, semi-tolerant and sensitive cultivars.