BINAMASUR-10, THE FIRST DROUGHT TOLERANT LENTIL VARIETY REGISTERED IN BANGLADESH

Received 05 July, 2019 Revised 23 August, 2019 Accepted 24 August, 2019 Online 31 August, 2019


INTRODUCTION
Lentil (Lens culinaris Medik) 2n =14, of the family Leguminosae, is one of the ancient food crops originated in the Fertile Crescent of the Middle East (Renfrew, 1969). It was first domesticated in Southern Turkey; from there it moved to Europe and Asia (Ladizinsky, 1979;Cubero, 1984). Lentil is one of the oldest annual food crops that have been grown over 8,000 years (Oplinger et al. 1990; Dhuppar et al. 2012). It is an annually sown, cool-season food legume crop. Lentil placed the second position according to area and production but stand first in terms of usage among the pulse crops in Bangladesh (Afzal et al. 1999). As a food, its grain contains high amount of protein (19-35.5 %), 59% carbohydrate, 0.7% fat, minerals (K, P, Fe, Zn) and vitamins (β-carotene) for human nutrition (Bhatty, 1988;Afzal et al. 1999). Due to its high protein content and quality, it is called 'poor man's meat' (Bhatty, 1988). Malnutrition has become a threatening issue in Bangladesh. Pulses can play an important role in this aspect. Moreover, its straw is a valued animal feed (Erskine et al. 1990) and its cultivation also helps to improve soil nutrient status by adding nitrogen, carbon and organic matter to soil (Sarker and Kumar, 2011). The priority of agriculture today has been shifted towards nutritional security and climate-smart agriculture. Drought stress is an extremely universal and disadvantageous cause for crop yield loss in several areas of the world where lentils are grown by forming a community (McWilliams, 1986;Shrestha et al., 2006). Lentil crop when sown during autumn or winter in South Asian countries as well as Mediterranean environments, are to face, occurrence of intermittent drought during the vegetative growth and terminal drought throughout their reproductive period when temperatures are everincreasing and rainfall is declining (Yusuf et al., 1979;Siddique et al., 1999;Shrestha et al., 2006). Lentil responses to drought are quite disagreeing; some workers reported that lentil is most sensitive to drought at seedling and flowering stages (Yusuf et al., 1979), while others reported that it is sensitive to drought at flowering and pod formation stages (Shrestha et al., 2006;Mishra et al., 2014Mishra et al., , 2016 Therefore, the present investigation was undertaken to develop drought-tolerant lentil variety with the potential to achieve high yields in difficult climatic conditions. The release of this variety, named Binamasur-10 is the result of a long-term collaborative research partnership between ICARDA and the Bangladesh Institute of Nuclear Agriculture. It was selected from among 150 lines that were provided by ICARDA including some advanced lines of BINA as it demonstrated outstanding performances in field trials, which were held in the drought-prone zones of the Rajshahi and Chapainwabgonj districts. Binamasur-10, with its drought-tolerant trait, is expected to be gradually adopted throughout the North-Western drought-prone districts of the country.

MATERIALS AND METHODS
Lentil accessions were collected from International Centre for Agricultural Research in the Dry Areas (ICARDA) including some advanced mutant lines from Plant Breeding Division, BINA. The field evaluation with 150 lentil accessions was conducted at BINA sub-stations Ishurdi and Magura, representative lentil growing areas of Bangladesh during 2006-2007. Thirteen accessions were selected based on yield and yield contributing characters. Preliminary yield trial was conducted with these 13 accessions along with popular, high yielding and widely cultivated variety BARI Masur-5 as a check to compare the performance of the accessions at Ishurdi and Magura during 2008-09, the study followed the randomized complete block design with three replications. Unit plot size was 2 m x 1.2 m. Row to row and plant to plant distances were 30 cm and 2-3 cm, respectively. Nine promising lines were selected based on earliness, disease reaction, yield and yield contributing characters. The advanced yield trials were conducted with these nine promising lines and BARI Masur-5 at the same locations during 2010-2011. The regional yield trials were also conducted with two accessions (amongst from nine promising lines) and BARI Masur-5 at Magura and Ishurdi during 2011-12. Yield related data were recorded from the study. Based on the yield performance of the previous years, on-station and farmers' field trials were also carried out with two promising lines and a popular check with BARI Masur-5. On-station trials (during 2012-13 & 2015-16) were replicated in thrice at Ishurdi, Magura, Rajshahi and Chapainawabganj and farmers' field trials (during 2012-13 & 2015-16) were non-replicated and practised at Ishurdi, Magura, Rajshahi and Chapainawabganj. The unit plot size was 10 m x 10 m in each location. Here also only yield data were recorded. Mean differences of different parameters including seed yield were tested by Duncan's Multiple Range Test (Steel and Torrie, 1960). Three accessions along with two check varieties, BARI Masur-4 and Utfala were tested against stemphylium blight, Rust and root rot/wilt at BINA sub-station farm Ishurdi and Magura. The incidence of foot and root rot of lentil was recorded at 10 days interval. The incidence of the disease was calculated by the following formula: Drought screening was carried out with three varieties and four lines at the glasshouse of Sibersdorf Laboratory in Vienna. Simultaneously, on-station trial was carried out at BINA sub-station Chapainawabganj and farmers field trials were conducted at drought-prone areas i.e in Rajshahi and Chapainawabganj district under rainfed condition. Four concentrations 0.0%, 10%, 15%and 20% of polyethene glycol (PEG-6000) were used to induce plant-water deficit stress in an aerated hydroponic system. For evaluating tolerance in the studied lines, STI (Stress Tolerance Index) were computed (Fernandez, 1992) as follow: where, YPi and YSi are the seed yield of lines in normal and stress conditions, respectively, and n is the mean of all lines in normal conditions. observed that significant differences were found for all the characters among the accessions except number of branches per plant. The shortest duration was observed for the accessions LG-96, and LG-22.

RESULTS AND DISCUSSIONS
LG-129 was the shortest and LG-137 was the tallest among the tested accessions for plant height.
LG-208 produced the highest number of pods followed by LG-73. The boldest seed with the highest 100-seed weight was observed in the accessions LG-73, LG-208 and LG-137. The accession LG-208 produced higher number of pods and the highest seed yield of 1987 kg/ha. Performance of accessions grown at Magura is presented in Table 5. Maturity period was the shortest for the accessions LG-96. The accession LG-73 was the tallest among the other accessions and the check variety. In case of 100-seed weight the highest 100-seed weight was observed in LG-208. Accessions, LG-208 and LG-73 produced higher seed yield of 1845 kg/ha and 1816 kg/ha and yield increased 31.21% and 22.11%, over the check, respectively. Evaluating the performance of the accessions, the better performed nine lines were selected for advanced yield trial with a popular check variety at Ishurdi and Magura during Rabi 2010-2011 (Table 3). The accessions LG-150 was the tallest among the entries. The accession LG-208 produced the highest number of pods/plant. The shortest maturity period was required for the entry LG-208 and also the highest seed yield was found in LG-208 at Ishurdi and Magura. Considering the superior performance of the selected accessions, multi-location yield trials were conducted with three selected line at three locations: Ishurdi, Magura and Jessore during Robi 2011-12 (Table 4). Results revealed that the accession LG-208 produced the highest number of primary branches as well as the highest number of pods per plant. This accession LG-208 also produced the highest seed yield at all the locations. Accession LG-208 also required the shortest maturity period. On-station and farmers' field trials were carried out with two promising lines and a check BARI Masur-5 at Ishurdi, Magura, Rajshahi and Chapainawabganj. On-station trials were replicated and farmers' field trials were non-replicated. Only seed yield per plot was recorded in Kg/ha. The exotic line LG-208 produced the highest seed yield in the research management practice at all the locations (Table 5). Similar trend of seed yield was found by the lines in farmers' management practices (Table 6). Average seed yield of 1852 and 1780 kg per hectare, for LG-208 and LG-209, respectively (Table 7).          Disease reaction against root rot and wilt complex, stemphylium blight and rust were examined in field from 2006 to 2008 at Ishurdi and Magura. Results are presented in Table 8, 9 and 10. The test accessions showed less infection than the check variety. The application of Rovral 50WP can control the disease when sprayed three times at an interval of 7 days starting from the initiation of the disease. The accession LG-208were found with less disease incidence against root rot compared to the susceptible and resistant variety Utfala and BARI Masur-4 (Table 8), respectively and this line also showed moderately resistant to moderately susceptible to stemphylium blight under natural condition ( Table 9). The cultivar Utfala is highly susceptible to stemphylium blight which is similar to the present findings (Sarker et al. 2004). Rust is also a major foliar disease in Bangladesh but it can be controlled with seed treatment. All the tested accessions along with a check variety, LG-208 showed moderately resistant to moderately susceptible to the disease. Genotype LG-208 had significantly highest seed setting and harvest index under 20% PEG induced drought and considered as the most tolerant which is correlated with field trials in drought prone areas (Chapainawabganj and Rajshahi). Drought screening was carried out with three varieties and four lines at the glasshouse of Sibersdorf Laboratory in Vienna. Drought stress was imposed to 14-days old seedlings. Observations were recorded on seed yield (Table 11). Results of analysis of variance showed that significant differences exist in terms of yield and harvest index between normal and stress condition. It indicates that not only the levels of drought induction had different effects on characters, but studied /varieties/lines had also different reactions to drought stress. Kumar et al. (2012) observed high diversity for biological yield, seed yield and HI in 43 genotypes of lentil in drought stress condition. The results revealed that drought stress decreased traits of seed yield and harvest index and it was clear that reaction of characters due to drought stress was different. Drought stress or water deficient had significant impact on yield and its components and in a study of Panahyan-e-Kivi et al. grain weight. Stress Tolerance Index (STI) introduced by Fernandez (1992) is a perfect tool to select, determine and identify the genotypes that have the maximum yield in normal and stress conditions. STI index revealed that the studied lines had high diversity in reflected to drought stress (Table11). While lines LG-208 and BARI Masur-6 in normal condition and in stress condition had maximum values of seed yield and harvest index, line LM-206-1, LM-512-1 and LM-206-2 had the lowest productivity in both conditions. Seed yield of LG-208 was more than BARI Masur-6 in both conditions. In accordance with Table 11, it revealed that genotypes LG-208 was the most tolerant line comparing to other lines. Therefore to cultivate in the area where lentil lines faces drought stress, this line might be recommended. On other hand, lines LM-206-1, LM-512-1, LM-206-2 and Binamasur-6 were the most sensitive to drought stress. This line is also tolerant to rust and stemphylium blight and seedling mortality rate is less than the other traditional varieties. In respect of yield potential and diseases reaction, LG-208 performed the best over year and location. Therefore, this exotic line has been registered as a variety, Binamasur-10 for cultivation all over the country.

CONCLUSION
Climate change is an added concern, increasing overall temperatures, altering the distribution of precipitation and aggravating drought conditions in numerous regions worldwide. Drought stress caused the substantial reduction in yield and its components. Results indicated that considerable variations exist related to yield and harvest index among the lentil varieties and lines. These traits could be used for screening drought tolerance in lentil. The results revealed that yield and harvest index were the main keys for indirect selection for tolerance to water stress. The exotic lentil line LG-208 i.e., Binamasur-10 has been found that had remarkable tolerance to drought stress. Binamasur Nawabganj. The variety has also economic significance to other districts that are Kushtia, Magura, Chuadanga, and Ishurdi. This variety can be cultivated in drought prone area to get a better yield.