Harvest index is a critical factor influencing the grain yield of diverse wheat species under rain-fed conditions in the Mediterranean zone of southeastern Turkey and northern Syria

Tohru Kobata,Müjde Koç,Celaleddin Barutçular,Ken-Ichi Tanno,Masanori Inagaki

doi:10.1080/1343943x.2018.1445534

Abstract

Environmental and plant factors critical to the grain yields of bread (Triticum aestivum L.), durum (T. durum L.) and emmer (T. dicoccum L.) wheat cultivars were investigated at two Mediterranean rain-fed field sites: Adana in southeastern Turkey (2009 and 2010) and Aleppo in northern Syria (2009). The grain yield (GY) and biological yield (BY) of most cultivars were higher in Adana than in Aleppo, and the lower GY in Aleppo resulted from lower harvest index (HI) and lower BY due to higher temperatures and lower rainfall. The variations in the HI among cultivars were greater in Adana than in Aleppo. The GY was closely related to the HI but not the BY across cultivars at each site, and a higher GY was accompanied by a superior conversion-efficiency of incident radiation during the grain filling period for grain yield [GY/Ra, where Ra is the cumulative radiation for 30 days after heading (D30)] across all observations. The GY/Ra correlated negatively with the average temperature for D30, and higher HI values resulted in higher GY/Ra. In Adana, the time from anthesis to physiological-maturity decreased as the average temperature for D30 increased, resulting in a lower HI. Cultivars exhibiting the early heading trait can effectively escape the negative impacts of terminal high-temperature and water-shortage conditions on the HI. The results suggested that the HI is a critical factor for GY across diverse wheat cultivars under terminal high-temperatures and water-shortages in Mediterranean areas, and the BY is also an important factor under severe water-limitation conditions.

Highlights

With a global annual production of 730 million t in 2015, wheat is one of the world’s most important food crops
Our objective in this study was to clarify the environmental and plant factors that are critical to the grain yield (GY) of cultivars of three background sources, bread (Triticum aestivum L.), durum (T. durum L.) and emmer (T. dicoccum L.) wheat, at two Mediterranean rain-fed field sites, southeastern Turkey and northern Syria
The cumulative rainfall increased from sowing to approximately 150 days after sowing, and two- or threefold higher levels were detected in Adana than in Aleppo in 2009

Summary

Introduction

With a global annual production of 730 million t in 2015, wheat is one of the world’s most important food crops. The capacity of these diverse wheat species to adapt to environmental stressors, such as high temperature and limited water supply, has been less well studied than that of bread wheat (Zaharieva & Monneveux, 2014). The importance of the BY and HI on the GY if different wheat species with diverse phenotypes in rain-fed areas of the Mediterranean zone, where increases in temperature and water shortages are more severe, is not well known. Our objective in this study was to clarify the environmental and plant factors that are critical to the GY of cultivars of three background sources, bread (Triticum aestivum L.), durum (T. durum L.) and emmer (T. dicoccum L.) wheat, at two Mediterranean rain-fed field sites, southeastern Turkey and northern Syria. Einkorn wheat cultivars were grown but not included in the evaluation due to the difficulty associated with grain filling due to their late heading traits

Methods

Results

Conclusion