**3.2 New herbicide-resistant lines were obtained by using the breeding method**

Herbicide resistance from wild species and resistant lines was transferred to cultivated sunflower by *hybridization* (*interspecific* and *intergeneric*). Self-pollination and yearly treating of the selected material were carried out. A high percentage of resistant plants was obtained from different crosses.

When treated with Pulsar 40 + Stomp 330 ЕК in 2009, 17 plants were killed and 4 were slightly affected out of 21 plants in total from hybrid material of the cross L. 1607 *Matricaria* sp. For three of them, a normal seed set was obtained [24]. Since then, a new elite inbreed line (**Figure 4**) has been develop, and it can be deployed in the making of herbicide resistant hybrids.

A.*H. argophyllus gophyllus*B.*H. petiolaris* C. *H. annuus* (w.f.).

**Figure 3.** *A.* H. argophyllus. *B.* H. petiolaris. *C.* H. annuus *(w.f.).* *Pesticides and Sunflower Breeding DOI: http://dx.doi.org/10.5772/intechopen.104478*

**Figure 4.** *Elite line from cross* H. annuus Matricaria sp*.*

**Figure 5.** *(A) Susceptible plants and (B) resistant.*

The introduction of genes for resistance to *IMI* from wild species or from resistant genotype into elite *B* or *R* lines is done by backcrossing accompanied with continual resistance screening and elimination of sensitive and yellow flash plants.

During the first 2 weeks, the phenotypical distinction of plants is observed: resistant, intermediate with less yellow flash, dead plants (susceptible) (**Figure 5**) and intermediate with severe "yellow flash" (**Figure 6**).

Heterozygous plants are less tolerant than homozygous ones. Therefore, different herbicide concentrations are needed for screening and selecting phenotypically the genotypes, without injuring the tolerant or killing the heterozygous plants.

This is clearly shown in field conditions (**Figure 7**). However, there arises a new issue: stress. Thus, plants develop at different rates during the vegetation (growing) season.

Now, we have 30 more inbreed lines and 150 forms in different generation (from hybridization and mutagenesis), resistant to herbicides (Pulsar or Express). Some of

#### **Figure 6.**

*Effect of imidazolonone herbicide treatments on the produced crop: 15 days after treatment the effect of "yellow flash" phenomenon is observed on some plants (the less resistant to completely susceptible plants).*

#### **Figure 7.**

*Breeding for tolerance to herbicides by hybridization. (A) Screening for resistance totribenuron-methyl (SU-res) and imidazolonone (IMI-res) herbicide in field trial conditions—susceptible (dead) and resistant (normally developing) plants. (B) One resistant from many plants and (C) plants at different rates of vegetation.*

#### *Pesticides and Sunflower Breeding DOI: http://dx.doi.org/10.5772/intechopen.104478*

them have specifically morphological traits: *mutation* as *white pollen color*, *fasciation*, *wrinkled leaf*, *zig-zag stem,* and other (**Figure 8**). Many of the lines were with good combining ability, increased 1000-seed weight, high seed oil content, early maturity, and resistance to some diseases. Some of the lines could directly be used as parent forms of sunflowers for human food.

Except through *hybridization*, *genetic variability* in cultivated sunflower can be increased by *mutations*. Induced mutations are caused by humans, by treating plants with various physical or chemical agents. Mutagens create a wide range of heritable changes in sunflower. Mutations are most frequently observed in morphological traits, oil quality, resistance to herbicides, resistance to low or high temperatures, and other traits. In fact, some of the new traits can be used as morphological markers.

There were some *deformations* of sunflowers (**Figure 9**) after treatment with herbicides. These defects often are a result of the impact of the stress factor and the

*3. Fasciation of stem*, *inflorescence* and *leaves;*

**Figure 8.**

*Mutagenesis. 1. Zig-zag stem. 2. White pollen color. 3. Fasciation of stem, inflorescence, and leaves. 4. Wrinkled leaves. 5. Yellow spotting. 6. Altered shape of inflorescence with densely spaced disk flowers. 7. Different colors of the ray flower and center of the head. 8. Funnel-shaped ray flower.*

inability of the plant to adapt to it. Some of the extreme cases are of fertile disk flowers (*f*) in the sterile inflorescence (*st*) or vice versa, but more often plants simply do not develop normally or cannot produce a next generation.
