In Lebanon, barley is mainly grown as a fall-sown crop in the drier (annual precipitation <500mm) northern Bekaa Plain, which has an average altitude of 1000m above sea level. Relative to the coastal lowlands in Lebanon or in the Mediterranean region of North Africa and West Asia, the Bekaa has a relatively long, cold, and snowy winter. Frost may occur as late as mid-April.
Barley is known to have originated from the Fertile Crescent, which included Lebanon. Local barley landraces are expected to have been grown here for a long time and are well adapted to the local conditions. Thus, by studying the local landraces, it is possible to get a good idea on the requirements for good adaptation on the Bekaa.
Sixteen barley accessions collected from different parts of Lebanon were studied in this investigation. They represented all the Lebanese accessions stored at the gene bank of ICARDA (the International Center for Agricultural Research in the Dry Areas). Three accessions were collected from around the town Baalbeck on the Bekaa, whereas the rest came from the coastal areas. The former was two row-type, but the latter was six-row type.
The accessions were planted in November at the Agricultural Research and Educational Center in a single-row nursery containing other barley materials. The three two-row accessions grew more vigorously in the winter, headed earlier, and gave much higher yield than the six-row accessions. Astonishingly, these three two-row accessions yielded much better than Rihane and ER/Apm, which were released in Lebanon in 1989 and 1997, respectively. Both cultivars were bred at and introduced from ICARDA.
The three two-row Bekaa accessions were also studied in an unheated greenhouse under three different planting dates. In the December planting, the three accessions headed later than ER/Apm and Rihane, but earlier than Tokak (the dominant barley variety in the Central Anatolian Plateau of Turkey). But in the two later plantings (Feb. 2 and Mar. 10), the three accessions stayed prostrate for a long time and headed the latest.
One of the three two-row accessions (ICB 121728) was further studied with other barley genotypes in the summer without any cold treatment. The heading dates of the different genotypes are given in Table 1. The spring-type check, Harmal, headed 37 days after planting. It was followed by ER/Apm, Rihane, Tokak, and Assi (released in Lebanon in 1997) in that order. ICB 121728, similar to Plaisant (winter-type check) and Tadmor, did not head by the end of August, i.e., 73 days after planting.
Table 1. Heading dates of different barley genotypes (planted on June 17, 1998).
| Barley genotype | Date of heading |
|---|---|
| Harmal (spring-type check) | July 23 |
| ER/Apm (released in Lebanon in 1997) | July 29 |
| Rihane (released in Lebanon in 1998) | August 11 |
| Tokak (dominant Turkish variety on the Central Anatolian Plateau) |
August 13 |
| Assi (released in Lebanon in 1997) | boot stage on August 18 |
| ICB 121728 (two-row landrace collected in the Bekaa) |
tillering stage on August 18 |
| Tadmor (selection from Syrian landraces) | tillering stage on August 18 |
| Plaisant (winter-type check) | tillering stage on August 18 |
These two greenhouse studies show that the three barley landraces from the Bekaa have a strong vernalization requirement like a winter type. This strong vernalization requirement probably is needed to delay flowering to avoid possible late frost damage. This view is partly supported by the fact that Rihane and Assi, the 2 barley varieties released in Lebanon recently, also have some vernalization requirement.
The strong vernalization requirement of the local barley landraces points out clearly that a spring type is not going to perform well in the Bekaa. A spring type may only be suitable as a catch crop to be planted in late winter or early spring. Unfortunately, this fact was not widely known or was ignored in the past. Over the past years, different strains of spring barley were sent or introduced from international agricultural research centers into Lebanon. It seems that many farmers delay sowing deliberately to reduce the chance of having frost damage to their barley crops.
The barley accessions from Bekaa, and Tadmor, which was selected from the local barley collected near Palmyra(Tadmor) in Syria, showed strong vernalization requirement. Thus from the little data available, it seems that the climatic environment in the northern part of Syria is quite similar to that in the Bekaa.
The data suggest that the Turkish variety, Tokak, has similar vernalization requirement as Rihane or Assi, i.e., Tokak has some vernalization requirement, but not strong requirement. However, Tokak headed very late under normal planting in the field. It appeared that Tokak is sensitive to day-length. As the last spring-frost may occur in May on the Anatolian Plateau, such daylength sensitivity may prevent Tokak from initiating flowering at daylength shorter than that occurring in May in Turkey.
The French winter-type barley, Plaisant, has a strong vernalization requirement. It did not have problems with late frost in the field, but did not yield well due to its late heading and slow maturing. Under European conditions, summer is warm and not dry, so crops can take time to mature slowly. However, under Mediterranean environments, terminal drought associated with heat stress is usually a constraint to high yield. Thus a winter barley from Europe usually does not give high yield in the Bekaa.
In conclusion, barley landraces from the Bekaa, have a strong vernalization requirement, suggesting that spring type is not going to perform well here.