Inheritance for resistance to herbicides (imidazolinone) in chickpea (Cicer arietinum L.)

One of the most important biotic stress factors which limit the chickpea (Cicer arietinum L.) production in the world is weeds. Weeds are one of the widespread problems for both winter and early spring-sown chickpeas. Weeds cause up to 98% loss of yield in winter sown chickpea fields. Even the weeds can be controlled by cultural, biological and chemical methods, cultural methods are the best ones to protect the environment. Nevertheless, cultural methods like rooting the weeds and grubing up by hand are expensive applications especially in wide areas due to increasing labour costs in chickpea grower countries. Instead of these, there are variety of herbicides that can be used as pre-sowing, pre-emergence and post-emergence. First two of the applications are not effective to control weeds which germinate later and chickpea is adversely affected by post-emergence herbicides. One of the most effective methods to control the weeds is to use imidazolinone (IMI) tolerant varieties. There have been efforts to find out IMI tolerant varieties by altering acetohydroxyacid synthase (AHAS) enzyme using mutation breeding and classical breeding methods. By using mutation breeding, a special mutant of Cicer reticulatum Ladiz. which can be easily crossed with the cultivated chickpea has been found which is toletant against imidazolinone (IMI). In this study, it is aimed to: (i) intrograte IMI-tolerant gene(s) from Cicer reticulatum Ladiz. into the cultivated chickpea, (ii) determine the heritability of herbicide tolerance, (iii) compare with AHAS or ALS (acetolactate synthase) enzymes and (iv) some amino acids in IMI-susceptible and IMI-tolerant chickpea genotypes. This project consists of two parts as field and greenhouse trials. Field trial which was conducted in ecological conditions of Antalya in which Department of Field Crops, Bati Akdeniz Agricultural Research Institute (BATEM), Ministry of Food Agriculture and Live Stock, located at Aksu, Antalya. Cicer arietinum L. (ACC 1054) (♀), the mutant of C. reticulatum (AWC 611HR) (♂) and F1 and F2 obtained from these parents and BC1 (ACC 1054 x F1 ve F1 x AWC 611HR) plants were used as plant materials. Herbicide with ai (active ingredient) of 100 g Imazethapyr (Pursuit®, BASF) was applied as suggested dose of 20 ml/da during seedling stage. After the application, chickpeas were evaulated for their phenological, morphological and agricultural traits according to 1-3 Scale (1=Tolerant and 3=Susceptible). Also, chlorophyll amounts were measured 7, 14 and 21 days after IMI herbicide application. These measurements were determined separately for each plant and control group (no herbicide application). 10 and 20 days after chlorophyll measurements, the relation between lysine, isoleucine, valine amino acids and resistance against herbicides and AHAS and ALS enyzmes were determined for tolerant and susceptible plants by taking leaf samples. Greenhouse trial was conducted in ecological conditions at Akdeniz University Seed Growing and Agricultural Biotechnology Research and Application Center, Antalya. Pre-trials of selected IMI group herbicide was completed on parent plants in greenhouse. Three seeds of parents were sown in each of four pots. One pot was reserved from each genotype as control when the plants reached seedling stage. Herbicide with 100 g/L Imazethapyr active matter was applied as the half of the suggested dose (10ml/da), suggested dose (20ml/da) and two times of the suggested dose (40ml/da) to one each of three remaining pots. 7, 14 and 21 days after the application, changes at the plants were observed and chlorophyll amounts were measured. Chickpea parents, hybrids (F1, F2) and back crosses (BC1) which were germinated at the nursery were transplanted in the greenhouse. Herbicide with 100 g/L Imazethapyr ai was applied to the one row of sown F1 plants at suggested dose of 20 ml/da. After the application, chickpeas were evaulated for tolerance against the herbicide according to 1-3 scale (1=Tolerant and 3=Susceptible). Other genotypes completed their normal growth and development periods. All the plant materials grown in the greenhouse were evaulated for their phenological, morphological and agricultural traits. 7, 14 and 21 days after the application, chlorophyll amounts of the entreated genotypes were measured. Similarly, chlorophyll amounts of the entreated genotypes were also measured. 10 and 20 days after chlorophyll measurements, the relation between lysine, isoleucine, valine amino acids and resistance against herbicides and AHAS and ALS enyzmes were determined for tolerant and susceptible plants by taking leaf samples. Because of interspecific breeding, hybrid vigour or heterosis (%) was determined at F1 plants. Besides, heterobeltiosis (%) was detected for number of pods and seeds per plant and biological yield and seed yield. Because of interspecific breeding and using mutant plants for breeding F2 plants, intensive transgressive segregations were detected by the means of yield and yield criterias. In the light of gathered findings; it is determined that the genes related with IMI resistance can be intrograte into the cultivated chickpea by hybridizations. As all of the F1 plants died after herbicide application, it is concluded that the gene or genes playing role in IMI tolerance were resesive. It is also determined that IMI resistance is polygenic by concluding that the genes controlling the divergences (IMI tolerant or IMI susceptible) of F2 and back crossed plants were located in the nucleus instead of the cytoplasm. AHAS enzyme was found to be higher in IMI tolerant chickpeas compared to the susceptible ones. Amount of chlorophyll was found to be similar in IMI tolerant chickpeas compared to the control group. In contrast, decrease of chlorophyll amount was detected in IMI susceptible plants. Lysine, isoleucine and valine amino acids were found to be higher at IMI resistant plants compared to susceptible ones. According to the findings; it is surmised that marker assisted selection (MAS) can be easily done with the AHAS level of the plants.