http://localhost:8080/handle/123456789/3756 Sat, 18 Apr 2026 13:43:48 GMT 2026-04-18T13:43:48Z http://localhost:8080/handle/123456789/4190 RESPONSE OF TRANSPLANTED AMAN RICE VARIETIES TO DIFFERENT SOIL MOISTURE LEVELS RAHMAN, MOHAMMAD MOHIDUR Due to irregular rainfall during aman season between July and November rice suffers from drought. Sometimes the farmers do not afford to provide irrigation in boro rice field; where providing irrigation in the aman rice field seldom happens leaving the best option to cultivate drought tolerant rice varieties in aman season. Considering the above conditions three pot culture experiments were carried out at Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during the period from July 2012 to November 2014 to study the performance of four transplanted aman rice genotypes (BRRI dhan56, BRRI dhan57, Binadhan-7 & BRRI dhan49) under three different soil moisture levels (100% field capacity moisture content or control, 70% of the control moisture and 40% of the control moisture). Another experiment under different PEG induced water stress conditions, was conducted to justify whether a lower soil moisture condition affects rice growth. The experiment was laid out in two factors Randomized Complete Block Design with four replications. The results indicated that plant height, tiller number, life duration, effective tiller, leaf area and total dry matter decreased under water stress. Increased dry matter investment to root in BRRI dhan49 helped to uptake more water under water stress. Relative water content, stomatal conductance and transpiration rate were found the highest at 100%FC condition and the lowest at 40%FC condition; but the reduction was comparatively lower in BRRI dhan56 and BRRI dhan49. BRRI dhan56 and BRRI dhan49 also performed comparatively better in PEG treatment. The grain yield and harvest index decreased with decreasing soil moisture in all the genotypes; BRRI dhan49 produced more than 90% relative grain yield under 70%FC treatment. Increased proline content in BRRI dhan56 and BRRI dhan49 helped them to give better yield under low soil moisture condition. The relative injury, chlorophyll content, soluble sugar content, starch content decreased with increasing water stress. The lower drought susceptible index (DSI) in BRRI dhan49 and BRRI dhan56 and higher in BRRI dhan57 and Binadhan-7 indicated that BRRI dhan49 and BRRI dhan56 were tolerant and BRRI dhan57 and Binadhan-7 were susceptible to water stress. A Thesis Submitted to the Faculty of Agriculture Sher-e-Bangla Agricultural University, Dhaka, In partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY IN AGRICULTURAL BOTANY SEMESTER: July-December, 2015 Tue, 01 Dec 2015 00:00:00 GMT http://localhost:8080/handle/123456789/4190 2015-12-01T00:00:00Z http://localhost:8080/handle/123456789/4189 RESPONSE OF RICE (Oryza sativa L.) GENOTYPES UNDER VARYING SUBMERGENCE DURATIONS AKHTER, NASIMA Three pot culture experiments were carried out in the field at Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during aman seasons of 2012 - 2014 to study the response of different rice genotypes under varying submergence durations and to identify the morphological, physiological and anatomical characters those contribute to submergence tolerance and to study the variations among the selected rice genotypes. The experiments were conducted with three tolerant (BRRI dhan52, IR64Sub1, FR13A) and one susceptible genotype (BR5) with four submergence treatments (0, 7, 14, and 21 days of submergence). All experiments were laid out in two factors RCBD with four replications. Different morphological and physiological processes were hampered due to submergence and there existed genotypic variations also. The lower stem elongation and less affected root dry matter help plants to survive under submergence condition. After desubmergence, tiller number, stomatal conductance, net assimilation rate, relative growth rate and absolute grain growth rate were less affected which helped BRRI dhan52 and FR13A to perform better. Different yield components such as number of panicles per plant, number of filled grain per plant, filled grain weight per plant and 100-grain weight were also less affected in BRRI dhan52 and FR13A compared to other two genotypes (IR64Sub1 and BR5). The results indicated that 7DS treatment in BRRI dhan52 produced more or less similar (99%) yield as compared to control which was followed by FR13A(81% of the control). Decreased grain yield per plant under submergence treatment was observed due to reduction in tiller number rather than grain weight per panicle. Larger aerenchyma formation, stronger arrangement of parenchyma, lower membrane leakage, higher proline content, higher stem carbohydrate and lower chlorophyll depletion in BRRI dhan52 and FR13A provided better adaptation capabilities of these genotypes under submergence condition. But in BR5, though the proline content was higher just after desubmergence, the injury label was much higher in this genotype and cells lost their normal physiological functions. Lower chlorophyll a/b ratio in BRRI dhan52 and FR13A indicated that chlorophyll a content was more affected and chlorophyll b content was less affected due to submergence. The genotype BRRI dhan52 showed more submergence tolerance compared to the other genotypes. A Thesis Submitted to the Faculty of Agriculture Sher-e-Bangla Agricultural University, Dhaka, In partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY IN AGRICULTURAL BOTANY SEMESTER: July-December, 2015 Tue, 01 Dec 2015 00:00:00 GMT http://localhost:8080/handle/123456789/4189 2015-12-01T00:00:00Z http://localhost:8080/handle/123456789/3757 PERFORMANCE OF DIFFERENT AUS RICE GENOTYPES UNDER WATER DEFICIT CONDITIONS JASMINE, HALIMA SAYEED ABSTRACT Water deficit encountered by rice plant is a common feature in Bangladesh especially in dry season for which rice is grown by supplying irrigation water. Aus rice is a dry season crop dependent on rain or irrigation. In Bangladesh, the Aus rice faces drought problem at vegetative stage. So, it is necessary to develop or introduce drought tolerant high yielding Aus rice varieties. Different rice research institutes like BRRI, BINA have released some drought tolerant rice varieties. Further improvement of those and other rice varieties are required in order to meet up the future rice demand. Considering the above statements four pot experiments were carried out during September 2012 to July 2014 at Agricultural Botany field of Sher-eBangla Agricultural University, Dhaka. Plants were grown in the rain protected polyethylene shelter to avoid rain under natural light conditions. The first experiment was conducted with eleven BRRI rice varieties (BR21, BR24, BRRI dhan42, BRRI dhan43, BRRI dhan48, BRRI dhan55) and other lines BR6976-11-1, OM1490, BR6976-2B-15 along with the tolerant check varieties Hashikalmi and Dharial. These rice varieties were used to find out their response of roots to water deficit in the soil of root elongation tubes. Due to water stress shoot height decreased and root length increased. And other three experiments were conducted with four drought treatments such as 0 days (control), 7, 10 and 15 days and drought imposed in different age of the plants in the earthen pots. The morpho-physiological and biochemical changes reduced plant growth rate due to water deficit affecting decline in leaf area, specific leaf area, shoot dry weight, panicle dry weight, panicle number, panicle length, number of effective tillers, total dry matter content, stomatal conductance, proline content and grain yield etc. After anthesis, the SPAD value gradually decreased towards maturity. Among the genotypes, BRRI dhan55 produced the highest number of tillers and grain yield per plant. It revealed that Hashikalmi showed significantly taller plant throughout the growing period and developed more tillers. The sensitive genotypes showed reduction in leaf area, number of leaf, dry matter, tiller number and took much longer time to recover and develop new organs. The grain sterility percentage was much higher in BR6976-2B-15 due to water stress treatment compared to other genotypes. The grain yield per plant recorded was the highest at control treatment and gradually decreased with the increasing water deficit duration in all the genotypes. But the grain yield was less affected in BRRI dhan55 and Hashikalmi due to water deficit treatment. Anthocyanin, and proline were increased, sugar and starch were decreased under water deficit conditions. Leaf accumulates anthocyanins under drought conditions and the red colour increased as the intensity of water deficit was increased. Under water stress condition RWC was significantly reduced. RWC declined with the increase of water deficit condition. Stomatal conductance was higher at early drought condition (1 st to 3 rd drought stress) and gradually decreased towards maturity at late water deficit condition (4 th to 6 th drought stress) in all the genotypes. Stomatal conductance was higher in BRRI dhan55 and Hashikallmi and lower in BR 6976-2B-15. The tolerant genotypes BRRI dhan55 and Hashikalmi were less affected under water deficit treatment compared to susceptible genotypes. Among the genotypes, BRRI dhan55 and Hashikalmi were tolerant and BR6976-2B-15, BR6976-11-1 was sensitive or susceptible to water stress considering the different parameters. A Thesis Submitted to the Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY IN AGRICULTURAL BOTANY SEMESTER: July-December 2015 Tue, 01 Dec 2015 00:00:00 GMT http://localhost:8080/handle/123456789/3757 2015-12-01T00:00:00Z