Diversity and geographic distribution of stem solidness and environmental stress tolerance in a collection of durum wheat landraces from Turkey

Variation and geographic distribution of stem solidness and environmental stress tolerance were assessed under dryland conditions in a collection of 2420 durum wheat landrace morphotypes collected in 28 administrative provinces of Turkey. The former trait is known to confer resistance to wheat stem sawfly – a serious pest insect in West Asia and North Africa. Both characters were scored on a visual five-level scale. Score mean values and frequency distributions in the different provinces were significantly different for both traits according to analysis of variance and chi-square test, respectively. Two groups of provinces emerged with high frequency of solid-stemmed, and hollow-stemmed accessions, respectively. The former could be of interest in durum wheat breeding against the sawfly. The group of solid-stemmed province germplasms was collected at lower altitude than the other, being also different on average for higher temperatures and evapotranspiration, and shorter growing season at sites of origin. Overall frequency of morphotypes tolerant to stress conditions prevailing in the evaluation site was rather low (10%). This low frequency may be due to low adaptation of materials in this harsher environment than those of origin where rainfall is usually higher and temperatures markedly lower. Nonetheless, differences among provinces in frequency distribution of stress tolerant morphotypes were evidenced. The relatively more tolerant gene pools originated either along the western coast or in the southern part of the country, along the Fertile Crescent. The least tolerant province germplasms originated either in the North along the Black Sea or in the highlands of the eastern Anatolian Plateau. Germplasm from provinces Malatya and Izmir combined good levels of both stem solidness and stress tolerance.     

Amelioration of water stress effects on wetland rice by urea-N,plant growth regulators,and foliar spray of a diazotrophic bacterium Klebsiella sp.

Some of the measures suggested for amelioration of drought effects include application of N fertilizer and plant growth regulators (PGRs). Since N₂-fixing bacteria produce plant growth substances (PGRs), the effect of foliar application of an active strain of Klebsiella sp. (KUPOS) on IR-50 rice was examined using three foliar sprays applied at 10-day intervals. Irrigation once every 3 days was essential for plant growth. Application of KUPOS and 40 kg N ha^-1 improved grain yield of acutely water stressed plants from 330 kg ha^-1 to more than 1300 kg ha^-1 along with an improvement in several growth variables and yield determinants. Indole acetic acid, kinetin and GA₃, in a mixture of 10^-4 M of each, were less effective than KUPOS in alleviating stress effects. The adverse effects of water stress on respiration and photosynthesis as indicated by CO₂ exchange were also alleviated by these treatments. While uptake of K, Mg, Ca, Fe and Mo was increased, Na content decreased, accompanied by an increase in proline content. The order of effectiveness of the treatments was 40 kg N ha^-1 >KUPOS>PGRs.