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Rice (Oryza sativa L.) is an important target crop for water use reduction because of its greater input water requirement than other crops. The pot experiment was conducted to evaluate the effect of two different levels [full irrigation and deficit irrigation (50% Plant Available Moisture)] on the growth, yield, chlorophyll content and water use efficiency of improved rice lines. Preliminary test for drought tolerance for the one hundred improved rice lines was conducted and screened under pot experiments in the dry season of 2018. After screening this test, the selected rice lines were grown at two different water levels in the screen house during the rainy season of 2019. Each experiment was assigned as a randomized complete block design with three replications at Yezin Agricultural University. The result of the preliminary test in 2018 found that among the one hundred YAU improved rice lines, seven lines were tolerant to deficit irrigation. In 2019, all selected rice lines were also tolerant to deficit irrigation. These lines also produced the best performance of the plant growth, the grain yield and yield component characters when compared with the checked variety. However, deficit irrigation for all selected lines reduced these characters when compared with full irrigation. The five rice lines under deficit irrigation produced the high chlorophyll content and water use efficiency when compared with full irrigation. Thus, it can be concluded that the highest drought-tolerant rice lines would be useful for plant breeding program. [ABSTRACT FROM AUTHOR]

Soil salinity has become a serious threat to crop productivity worldwide. Salt tolerance for rice varieties vary with different stages against salinity. This study was to evaluate the effect of three different levels [0.2, 6.0, and 8.0 dS m-1] of salinity on the growth and yield of improved rice lines at different growth stages. This study was conducted as two-factor factorial in a randomized complete block design with three replications at Yezin Agricultural University in 2017 and 2018. After screening at seedling and vegetative stages, the selected rice lines were grown at three different salinity levels [3.3, 6.0, and 7.6 dS m-1] in the field. Among the one hundred improved rice lines, thirteen lines were tolerant to 8.0 dS m-1 during three weeks of application at seedling stage. Studies at vegetative stage showed that these thirteen lines were tolerant to 6.0 dS m-1 during six weeks of application. However, seven rice lines were moderately tolerant to 8.0 dS m-1 during six weeks of application in term of leaf mortality. In the field experiment, all seven rice lines were tolerant to 6.0 dS m-1 at all growth stages, whereas death occurred at 7.6 dS m-1. All agronomic parameters such as tiller numbers, panicle numbers and grain numbers per panicle were grown up to maturity under 6.0 dS m-1 at field condition. All these parameters were found to be major cause of yield reduction under saline conditions. [ABSTRACT FROM AUTHOR]