**3.3 A new line with resistance to herbicides Pulsar and Express was developed**

The aim of the first experiment was to establish genetic variability (*geneplasm*) and sources (wild species and cultivated sunflower forms and lines) of herbicide resistance. The field trial was separated in three parts: the first part for treatment with herbicide Pulsar 40 (120 mL/dka)—*P*, the second part used as a control (not treated)—*K*, and the third part for treatment with Express (5 g/dka)—*SU* (**Figure 10**). The materials were sprayed during the optimum time as to test them for resistance to IMI herbicides is the stage of three to five pairs of permanent leaves. The dose of Pulsar was found to

**Figure 9.**

*Deformations of sunflower after treatment with herbicides. 1. Branching (A), hardening (B), elongation (C) and breaking at the base (D) of the stem. 2. Deformation of the inflorescence. 3. Fertile disk flowers (*f*) in the sterile inflorescence (*st*) or vice versa.*

effectively control several weeds and have a highly effective control of parasite broomrape (*O*. *cumana*), but it was not so capable of controlling *Convolvulus arvensis* properly.

The 2020 and 2021 placement of the crops is laid out in the same way, but the treatment doses are increased—165 mL/dka for Pulsar and 6.2 g/dka for Express

**Figure 10.** Р *group,* K *group, and* SU *group.*

**Figure 11.** Р *group,* K *group, and* SU *group in experiment, 2020.*

**Figure 12.** *Drought impact.*

(**Figure 11**). This increase is in order to clear the heterozygous plants faster, i.e., to leave only those fully resistant (homozygous) to herbicides.

The drought during (**Figure 12**) this period was an additional stress factor besides the increased concentration of the chemicals. But, despite everything, we still have new elite *B* lines.

**Figure 13.** *Mutant line with new morphological traits, 2015. A and B: Mutant plant. C: Leaf. D: Inflorescence and leaf.*

Herbicide resistance (IMI and SU) was successfully transferred from the different sources into elite *R* and *B* lines. Two years ago, we, *Mihsan* breeding group, reported a new form of sunflower with a new type of combined resistance to herbicides [42] (**Figure 13**). The study continued, and now, we have a line in homozygous state that is suitable for molecular analysis, which is the only thing that can show exactly what has happened.

The initial cross was between our mutant line and one American line, IMI type. The aim was to transfer IMI resistance into the morphologically specific line. The first treatment was done on the F2 generation. Seeds from IMI resistant F2 plants were divided into three groups. Every one of two groups was treated separately with herbicide Pulsar (*Р* group) or Express (*SU* group). The received result was a very high percentage (60–95%) of alive plants in both the groups. After self-pollination, in F4 hybrid generation, four numbers (all from seeds of only one plant from the previous year) from the *SU* group and five numbers from the *Р* group were with 100% alive plants. The original F2 plants are the initial parents of two of these numbers. The mentioned two numbers from the *Р* group were used as donors of pollen for hybridization of seven not-resistant to herbicides B lines after emasculation. The aim was to understand how this new trait transmits (the mode of inheritance). F1 and F2 plants were treated with Pulsar. A different percentage (20–80%) of alive plants was received in every one of crosses. F2 plants were received from alive isolated F1 plants. The results were varying—numbers with all dead plants, numbers with all alive plants, and numbers with different percentage (7–92%) alive plants.

In 2020 and 2021, the treatment doses were increased for both detergents. As a result, in 2021, four numbers with plants in the sixth hybrid generation were homozygous for trait resistance to both herbicides. These were already *new elite B lines*. Out of the treated 11 lines, in one, all the numbers were dead in both the groups of

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

treatment. In this same sixth generation, and with increasing treatment doses, a different and very interesting result was obtained, namely, in three lines, all numbers showed complete resistance to herbicide Express, but when treated with Pulsar, some of the plants were affected. It is also interesting to note that 95% of the affected plants die after the Pulsar treatment, and up to 2% of the plants produce only a few seeds. On the other hand, the plants affected by Express branch and deform their inflorescence, but about 80–90% of them survive. In a small proportion of these plants, however, no seed set is obtained after isolation and self-pollination. Three numbers of F4 plants from crosses between not-resistant B lines and plants with this new trait—resistance to both herbicides—show complete resistance to both herbicides.

## **4. Conclusion**

In conclusion, it can be said that sunflower breeders use various methods in order to get new *genetic variability* (by interspecific and intergeneric hybridization and mutagenesis) in new elite lines that after having their combining abilities examined are later used for making new hybrids. The choice of methods is closely connected to the breeding goals set in advance, as well as the available staff, equipment, inheritance of the most significant agronomic traits, available genetic resources, and other factors. Molecular marker-assisted selection (MAS) can also be used to check herbicide tolerance.

The chemical industry is constantly creating new pesticide agents that are highly selective, slightly poisonous to humans, decompose quickly, and do not contaminate crop production. In this way, many of the disadvantages of the chemical method are avoided, and the possibility of widespread application is improved. Despite the increased use of biofertilizers and various biological control methods (entomopathogenic bacteria and fungi, predatory insects, parasitic insects, etc.), *the creation of resistant varieties* (both to the pests themselves and to the used chemicals), and many more, which make it possible to reduce the use of pesticides, the question arises: Which is the best and safest option for us, humans? Everyone has to answer for themselves, finding the balance between all the options, while trying to preserve the environment.

#### **Acknowledgements**

I would like to thank *Mihsan* Ltd. for giving me the opportunity to present these results and photographs.
