In the Central Anatolian Plateau (CAP) of Turkey, the barley improvement programs traditionally focused on drought and winterhardiness with only a limited consideration to adaptation to micronutrient problems in the soil. However, in a FAO survey on top-soil for micronutrient deficiency in the 1970s, Turkey was found to be one of the countries with the highest boron (B) levels among 30 countries in the world, and it was suggested that B toxicity could be a problem in some areas in the CAP. Severe symptoms of B toxicity in barley and wheat were observed for many seasons at the Hamidiye field station near Eskisehir. Tokak (Tokak 157/37), the predominant barley variety in the CAP since its release in 1963, was recently found to be tolerant to high levels of soil B.

After considering the suggestions that high B soils could be a quite widespread problem in the CAP and that B-toxicity tolerance should be incorporated into future barley varieties, a project with the same title as this article was initiated in 1995. The aims are: (i) to quantify the degree and extent of B toxicity in the CAP, and (ii) to identify and develop barley varieties with high tolerance to B toxicity.

This project is the first to involve three different institutes in Turkey, and the International Center for Agricultural Research in Dry Areas (ICARDA). The personnel participating in the projects are: Muzaffer Avcí, Hüseyin Tosun, Taner Akar, and Nuzret Zencirci of the Central Research Institute of Field Crops (CRIFC), Ankara; Müfit Kalaycí, Arif Cíldír, and Turgrul Ince of the Transitional Zone Agricultural Research Institute (TZARI), Eskisehir; Fikret Eyüboglu of the Soil and Fertilizer Research Institute (SFRI), Ankara; and Sui-Kwong Yau, John Ryan, Mohamed Tahir, and S. Beniwal of ICARDA.

In 1995 and 1996, advanced lines from the CRIFC and TZARI were grown at Hamidiye, the high B site, and screened for B-toxicity tolerance at the seedling stage in a plastic house at ICARDA, Tel Hadya, Syria. The plot of grain yield of 102 lines at Hamidiye in 1996 versus the seedling B-toxicity symptom score is shown in figure 1. There was a high linear correlation of -0.64 (P<0.001) between the two traits. High yielding lines in the high-B site had high B-toxicity tolerance. This result shows clearly the usefulness of the seedling screening technique. Based on the seedling test, there was moderate, but significant, variation between entries. Most of the 226 lines screened so far were fairly tolerant. The least tolerant entries had less severe symptoms than the very susceptible check, Pirate. Twenty-four entries had less severe symptom scores than Tokak.

A survey of B-toxicity symptoms in farmers' barley fields was carried out in CAP in May 1996. During the 5-day journey, a stop was made every 10 to 15 km to check for B-toxicity symptoms. A total of 92 fields were surveyed. Most of the fields having moderate to high B-toxicity symptoms were in Ankara, Konya (where B probably associated with salinity), and Kirsehir areas. No symptoms were observed in farmers' fields in the high-rainfall Kutahya, Usak and Afyon areas as expected. Surprisingly, symptoms were also not detected in the Eskisehir area, except at Hamidiye Station. This might be caused by the uncommon event in the Eskisehir area that immediately after the cool April, there were high temperatures and no rain for three weeks. Thus roots of the stunted plants in the visited fields probably did not have the chance to reach the B layer in the subsoil.

During the survey two plant samples with and without symptoms were taken from each field whenever possible. A sample of the top-soil was also taken at a spot where plants with symptoms were found. Samples from this survey and from the soil survey of 1995 are being analyzed.