The results suggested that all the pure Basmati lines or genotypes initiate flowering within a specific range of day length duration and temperature. Delaying the transplanting date did not significantly affect the fl...The results suggested that all the pure Basmati lines or genotypes initiate flowering within a specific range of day length duration and temperature. Delaying the transplanting date did not significantly affect the flowering time of studied Basmati lines. Maximum threshold of daily minimum temperature (MT) was 24°C during both the years. Likewise, maximum threshold of daily day-length (DL) durations was 12 hours and 18 minutes during both the study years. Results showed that the flowering was maximum when the MT and DL values were optimum as depicted by peak of the trend lines, where maximum lines flowered. Maximum flowering initiations took place when DL was about 11 hours and 15 minutes indicating Basmati as short day plant which flowers maximum when day lengths are shorter and dark or night duration is longer. During 2013, 1st date trial showed strong relationship between flowering initiation with dates of flowering during the flowering period as depicted by higher regression (R2 = 0.837) values. In 2nd date trial during the same year, the value is lower (R2 = 0.513) depicting less relationship of flowering initiation with the dates of flowering. The same trend was observed in 2014 trial. In 1st date trial, strong relationship between flowering initiation with dates of flowering during the flowering period as depicted by higher regression (R2 = 0.864) values, was observed. In 2nd date trial during the same year, the value is lower (R2 = 0.1789) depicting very poor relationship of flowering initiation with the dates of flowering, and the same trend (R2 = 0.0544) in 3rd date of trial.展开更多
Rice is food for more than half of the world population and the most consumable cereal in most of the countries. Pakistan is the fifth largest exporter of rice. However, Bacterial leaf blight (BLB) caused by Xanthomon...Rice is food for more than half of the world population and the most consumable cereal in most of the countries. Pakistan is the fifth largest exporter of rice. However, Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae is the most devastating and serious threat to rice production in many countries of the world including Pakistan. To combat this disease, innate genetic resistance of the plant plays vital role along with being environmentally friendly and economical. In this study, thirty-one (31) Near Isogenic Lines (NILs) having Xa4, xa5, Xa7, xa13 and Xa21 reported BLB tolerant genes and 34 locally developed rice lines were investigated under natural field conditions at three agro-ecologically different locations with highest disease occurrence records (BLB hotspots) viz., Sheikhupura, Hafizabad and Gujranwala, Punjab, Pakistan in order to assess their respective genetic resistance and G × E interactions against the disease. Thirty-one (31) lines were categorized under resistant cluster, twenty-eight (28) were moderately resistant, six (6) were moderately susceptible and one (susceptible check) was in susceptible category. Grouping of different lines/varieties under same cluster shows their significantly similar response against BLB disease in corresponding environment. Among the studied NILs, only one line showed polymorphism for all five resistant genes, two lines had four;seven lines had three genes, seven lines showed di-genic while five lines showed mono-genic polymorphism. These resistant lines with multiple-genes for BLB resistance can be evolved as a new BLB resistant variety and also be utilized as donor parent in breeding programs for developing new cultivars with horizontal resistance against more than one target pathotypes and environments. Xa4 and xa13 were found to deliver significant resistance against the local pathotypes in studied germplasm and NILs.展开更多
文摘The results suggested that all the pure Basmati lines or genotypes initiate flowering within a specific range of day length duration and temperature. Delaying the transplanting date did not significantly affect the flowering time of studied Basmati lines. Maximum threshold of daily minimum temperature (MT) was 24°C during both the years. Likewise, maximum threshold of daily day-length (DL) durations was 12 hours and 18 minutes during both the study years. Results showed that the flowering was maximum when the MT and DL values were optimum as depicted by peak of the trend lines, where maximum lines flowered. Maximum flowering initiations took place when DL was about 11 hours and 15 minutes indicating Basmati as short day plant which flowers maximum when day lengths are shorter and dark or night duration is longer. During 2013, 1st date trial showed strong relationship between flowering initiation with dates of flowering during the flowering period as depicted by higher regression (R2 = 0.837) values. In 2nd date trial during the same year, the value is lower (R2 = 0.513) depicting less relationship of flowering initiation with the dates of flowering. The same trend was observed in 2014 trial. In 1st date trial, strong relationship between flowering initiation with dates of flowering during the flowering period as depicted by higher regression (R2 = 0.864) values, was observed. In 2nd date trial during the same year, the value is lower (R2 = 0.1789) depicting very poor relationship of flowering initiation with the dates of flowering, and the same trend (R2 = 0.0544) in 3rd date of trial.
文摘Rice is food for more than half of the world population and the most consumable cereal in most of the countries. Pakistan is the fifth largest exporter of rice. However, Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae is the most devastating and serious threat to rice production in many countries of the world including Pakistan. To combat this disease, innate genetic resistance of the plant plays vital role along with being environmentally friendly and economical. In this study, thirty-one (31) Near Isogenic Lines (NILs) having Xa4, xa5, Xa7, xa13 and Xa21 reported BLB tolerant genes and 34 locally developed rice lines were investigated under natural field conditions at three agro-ecologically different locations with highest disease occurrence records (BLB hotspots) viz., Sheikhupura, Hafizabad and Gujranwala, Punjab, Pakistan in order to assess their respective genetic resistance and G × E interactions against the disease. Thirty-one (31) lines were categorized under resistant cluster, twenty-eight (28) were moderately resistant, six (6) were moderately susceptible and one (susceptible check) was in susceptible category. Grouping of different lines/varieties under same cluster shows their significantly similar response against BLB disease in corresponding environment. Among the studied NILs, only one line showed polymorphism for all five resistant genes, two lines had four;seven lines had three genes, seven lines showed di-genic while five lines showed mono-genic polymorphism. These resistant lines with multiple-genes for BLB resistance can be evolved as a new BLB resistant variety and also be utilized as donor parent in breeding programs for developing new cultivars with horizontal resistance against more than one target pathotypes and environments. Xa4 and xa13 were found to deliver significant resistance against the local pathotypes in studied germplasm and NILs.
