EFFECTS OF DIFFERENT LEVELS OF NaCl ON THE SEED GERMINATION OF CYAMOPSIS TETRAGONOLOBA L

Effects of four different levels of NaCl (05, 10, 15, 20 dS/m) on the seed germination of cluster bean (Cyamopsis tetragonoloba L.) cultivars were investigated. Only distilled water was used in the control. The experiment was conducted in the Petri dishes under laboratory condition and laid out in CRD comprising five replicates. The results indicated that the germination index (GI), seed vigor index (SVI), germination stress index and seedling length (radicle and plumule) decreased with increase of salinity levels and germination percentage (GP) was reduced significantly at the highest level of salinity (200 mM). However, mean germination time (MGT) and time taken for 50% germination (T50) increased by increasing salinity levels. Correlation coefficient between all possible combinations was estimated and the results indicated that GP, GI, MGT, T50, and SVI had significant positive or negative correlation with each other. Introduction Salinity is one of the major environmental stresses that decrease the crop production particularly, in the arid and semi-arid areas of the world (Schleiff 2008). Total salt affected area of the world is about 7% (Musyimi et al. 2007) and it is mainly restricted to arid and semi-arid regions where land degradation and population growth are of major concern (Geissler et al. 2010). In Pakistan, nearly 10 M ha areas are affected by different levels of salinity and it consists of 12.9% of total land in the country. The problem of salinity in the irrigated area of Pakistan occurred due to inadequate drainage practices (FAO 2008). Seed germination plays important role towards yield (Sanchez et al. 2014). To start with the process of germination of seeds, absorption of water is the first step that should occur under favorable environmental conditions (Tobe et al. 2001). Salinity of growth medium delays or prevents seed germination and later on seedling establishment and such conditions prevail mainly due to evaporation of water under high temperature. Germination percentage and seed vigor index are the important criteria for selection of salt tolerant cultivars (Bybordi 2010). Cluster bean (Cyamopsis tetragonoloba L.) also known as Guar is an important summer legume crop in Asian countries (Rao and Shahid 2011). It is mostly grown in the arid and semiarid regions and its uses are of multifarious nature as it is used for human consumption as well as forage for cattle (Satyavathi et al. 2014, Choy et al. 2015). Seeds of Guar contain Guar gum which is being used in wide range of industries such as textile, pharmaceutics, food industry, paint, and cosmetics (Mudgil et al. 2014, Jukanti et al. 2015). In view of the importance of cluster bean in the agrochemical industries and due to agrobotanical characters of this crop, this is gaining considerable attention to grow on abiotic stress hit areas (Ali et al. 2015). It is therefore, worthwhile to consider the problems caused by salinity in the production of this important crop and the main aim of the present study, was to examine the seed germinated and vigor indices under salinity stress. *Author for correspondence: <abubakar@ciitvehari.edu. pk>. Department of Horticultural Sciences, Faculty of Agriculture and Environmental Sciences, The Islamia University of Bahawalpur, Pakistan.