Genetic diversity in mutated and non-mutated rice varieties.

We studied the genetic variability due to mutation induced by γ-rays (10, 15, and 20 Kr) on various traits of twelve rice genotypes. Mutated and non-mutated seeds were sown in the field between July 2013 and 2014 using a split plot design. Yield and yield-related trait data was recorded, which showed significant (P < 0.05) genotypic and irradiation effects. Gamma radiation exerted non-significant effects on the panicle length of all plants, indicating the uniformity of performance of this character at different radiation levels. The plant height, grains per main panicle, panicle length, 1000-grain weight, grain weight per main panicle, and fertility percentage was minimum in Basmati-198, Basmati-Pak, Shaheen-2000, Super Basmati, Basmati-385, and Super Basmati, respectively, when exposed to radiation at 20 Kr. However, Basmati-370 attained maximum flag leaf area at this level of radiation. Broad sense heritability ranged from 72.0 to 97.7%, indicating the possibility of selection during earlier generations. Phenotypic correlation was positive and significant between grain weight per main panicle with panicle length and flag leaf area. Number of grains per main panicle and genotypic correlation were positive among grain weight per main panicle, panicle length, fertility percentage, 1000-grain weight, and plant height, indicating the effectiveness of these traits in the selection for yield. Phylogenetic analyses revealed a pair-wise similarity ranging from 0.51-0.76 before mutation and 0.39-0.89 after mutation. This study proved that γ-rays at 20 Kr would be most effective in creating genetic variability in the existing germplasm.

A low-cost intervention for cleaner drinking water in Karachi, Pakistan.

OBJECTIVE: To pilot test an inexpensive, home-based water decontamination and storage system in a low-income neighborhood of Karachi. METHODS: Fifty households received a 20-L plastic water storage vessel with a high-quality spout and a regular supply of diluted hypochlorite solution. Twenty-five control households were recruited. Water samples were collected at baseline and during unannounced follow-up visits 1, 3, 6, and 10 weeks later. RESULTS: Baseline drinking water samples among intervention households were contaminated with a mean 9397 colony-forming units (cfu)/100 mL of thermotolerant coliforms compared with a mean 10,990 cfu/100 mL from controls. After intervention the mean concentration of thermotolerant coliforms decreased by 99.8% among the intervention households compared with an 8% reduction among controls. Two years after vessel distribution, 34 (68%) of the families were still using the vessel. Thirteen of the households had stopped using their vessel because it had broken after more than 6 months of use, a pattern most consistent with ultraviolet radiation-induced degradation of the plastic. CONCLUSIONS: In a highly contaminated environment, a specifically designed water storage container and in-home water chlorination was acceptable and markedly improved water quality. Where plastic water vessels will be exposed to substantial sunlight, ultraviolet light stabilizers should be incorporated into the plastic.