Photosynthetic Properties and Potentials for Improvement of Photosynthesis in Pale Green Leaf Rice under High Light Conditions
The genetic diversity of durum wheat (Triticum durum Desf.) is held by landraces, which are generally considered to be endemic to a particular region to which they are well adapted. To evaluate the effect of climate in the countries of origin on their agronomic performance, 172 durum wheat landraces from 21 Mediterranean countries were grown in northeastern Spain. Average long-term climatic data of the main wheat-growing areas in each country of origin allowed us to identify four climatic zones in the Mediterranean Basin, steadily varying from warm and dry to cool and wet. The phenology, biomass, and yield of landraces were affected by the climatic zone of origin. The climatic zone accounted for 32.8, 28.3 and 14.5 % of variance for days to anthesis, plant height, and grain filling rate, respectively. The number of days to heading and anthesis steadily increased when moving from the warmest and driest zone of origin to the coldest and wettest one. Landraces collected in the warmest and driest zone had a smaller biomass, a lower chlorophyll content in the flag leaf, more fertile tillers, spikes and grains m−2, a lower grain filling rate, lighter grains, and lower yields than those originated in colder and wetter zones. Landraces collected in countries with high solar radiation showed a shorter cycle until anthesis and smaller height and biomass accumulation, while higher temperatures after anthesis resulted in more tillers and spikes. Landraces from countries with high potential evapotranspiration during grain filling had significantly lower grain filling rates and grain weight.