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Wheat Information Service
Number 75: 21-25 (1992)

An attempt to transferring stem solidity of Triticum aestivum to triticale (2n=6x=42). I. Investigations in F₁

S. M. Tsvetkov

Institut for Wheat and Sunflower, General Toshevo, Bulgaria


Summary

The stem solidity in wheat appears an decisive factor for the resistance to damages by wheat stem sawflies. A transfer of the solid stem from Triticum aestivum in triticale (2n=6x=42) was conducted through the use of the wide hybridization methods in a breeding way by application of simple and complex crosses. The solid stem of MBX-11-7 winter soft wheat was inherited dominantly in F₁ crossing with the 42-chromosome triticale T- AD-17-B (with hellow stem). The hybrid plants in F₁ with solid stem are distinguished for a lot of high meiotic disturbances reaching 96.80% compared to 46.36% for the male parent from male T-AD-17-B and 2.22% for the female parent form female MBX-11-7.


Introduction

Today it is known that the stem solidity, both in wheat and triticale, appears as decisive factor for their resistance to damages by European wheat stem sawfly Cephus pygmaeus L. (Yamashita 1937; Platt and Larson 1944; Larson 1959; McKenzie 1965; Tsvetkov 1973). According to Holmes and Peterson (1958, 1960, 1961) and Roberts (1954) the resistance in wheat, as related to the sawfly, can be divided into three categories: (1) lack of appeal to the ovipositing female and resistance to oviposition, (2) suppression of egg hatching or larval tunneling, and (3) nutritional requirement of larval. Holmes and Peterson (1962) established that the largest larval mortality occurs in solid stemmed wheat. The triticale varieties distributed now, similar of wheat and rye, are distinguished for hollow stem and poor resistance to the basic wheat pest.

In the literature there are no cases indicating the solid stem transfer from T. aestivum in triticale (2n=42) with the aim to develop forms with a solid stem resistance to Cephus pygmaeus L.


Materials and methods

The method of hybridization T. aestivum (solid stem) x Triticale (2n=42, hollow stem) was used. Winter common wheat MBX-11-7 (Bulgaria, solid stem), and triticale T-AD-17-B (Bulgaria, hollow stem) and AD-No.11 (Maya II-ARM"S", Mexico, hollow stem) were used as components for crossing.

Stem solidity was determined by three cross sections in the first top (ear-next) internode and by a cross section in the middle of every next (2nd, 3rd, 4th). The cross section of the first top internode were made 2.5 cm below ear, in the middle of the internode and 2.5 cm above the base (McNeal 1961). Degree of stem solidity was determined by the scale of Sapegin (1938) and that of Larson (1959): 1=hollow stem (thin walls); 2=hollow stem (thick walls); 3=intermediate stem solidity; 4=solid stem with extremely opening; 5=solid stem.
The analyses of the meiosis in PMC was conducted on preparations through squeezing of the object (Nikolov 1966).

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