Zaheer Ahmad

GENOTYPIC VARIATIONS OF PHOSPHORUS UTILIZATION EFFICIENCY OF CROPS

Intra-specific variations of phosphorus-utilization efficiency (PUE) hold great promise in rationalizing the application of cost-intensive phosphatic fertilizers in resource-poor situations, and to extend the useful life of the phosphate reserves in the world. In developed countries, efficient P-using crops may find significance in protecting the environment by reducing pollution of surface and ground water resources. This paper briefly reviews some of the work done so far on genotypic variations of Phosphorus (P)-nutrition of crops. Several physiological mechanisms responsible for such variations have been recognized. Various screening techniques to select P-efficient genotypes are also discussed. In addition, a brief historical account is also given on plant genetic approach to tackle soil problems.

Phosphorus nutrition of cotton cultivars under deficient and adequate levels in solution culture

In low-input agricultural systems that characterize most of the developing world, nutrient-efficient crop cultivars may play significant role in improving crop productivity. Phosphorus (P) deficiency is a common phenomenon in cotton growing areas of Pakistan, however the farmers are reluctant to apply it due to its price and fear of lack of response. A solution culture experiment was conducted to evaluate 10 commonly grown cotton cultivars for their relative efficiency to utilize deficiently and adequately supplied P, using Johnsons solution. Phosphorus deficiency markedly reduced shoot dry weight (SDW), root dry weight (RDW), whole plant dry weight controlled by plant P contents under P deficient conditions, suggesting an internal regulation in addition to the influence exerted by external P supply. The conclusions from experiment were that differences in growth existed among cotton cultivars exposed to same P concentration in the growth medium. Cultivars, which were efficient in both P-acquisition and P-utilization, were efficient accumulators of biomass under adequate as well as deficient level of P supply.

Calcium and salt-tolerance of rice

The impact of calcium (Ca) supply on the growth and yield of rice was studied in nutrient and soil culture experiments. In solution culture experiment, the effect of external‐Ca supply (0.5, 1.0, 1.5, 2.0, 3.0, 4.0 mM Ca) on the growth and shoot composition of two rice cultivars, varying in salt‐tolerance, in the presence and absence of 100 mol m− 3 NaCl was measured in a four week trial. In soil culture experiment, Ca (as gypsum; CaSO4 · 2H2O) was applied at the rates of 0, 10, 25, 50 and 100% of gypsum requirement (GR) of the saline‐sodic soil (after determining its GR). A positive, improving and stimulative effect of Ca was noted in growth characteristics (shoot and root weight and tillering capacity) in both the cultivars at 1.0 to 1.5 mM Ca; above this concentration, Ca had inhibitory effect. Although increasing supply of Ca tended to decrease sodium (Na) and chloride (Cl) concentration in the shoots of both rice cultivars, shoot‐concentrations of Na and Cl were much lower in NIAB‐6 (salt tolerant) than IR 1561 (salt sensitive). An increase in potassium(K):Na ratio, an indication of salt tolerance, was observed at 1.0 mM Ca and above in both rice cultivars under saline environment. Result, confirmed in salt affected soils of two different types (saline and saline sodic), showed an improvement in the paddy yield of both salt tolerant and salt sensitive rice cultivars due to Ca application as gypsum at the rate of 25% of GR of soil. Excessive rates of Ca either in solution culture or soil were detrimental for plant growth and paddy yield. The ameliorative effect of Ca was because of increased Ca:Na ratio of the growth medium.

Rifaximin Therapy in Patients of Irritable Bowel Syndrome Without Constipation Randomized Controlled Trial

Irritable Bowel Syndrome (IBS) is a common condition affecting lives of patients across the globe. The statistics are much worse than previously thought. Studies showed that 9 23% of the world population is suffering from IBS. Very few options are available with inadequate efficacy and a dire need for newer options. Rifaximin is one such promising drug. This study has been conducted to determine the efficacy of rifaximin therapy in IBS patients. Objective: The efficacy of rifaximin was compared with a placebo in controlling the symptoms of irritable bowel syndrome. Study design: Randomized Controlled Trial. Setting: Medicine Outpatient Clinical Department, Allied Hospital, Faisalabad. Duration of study: 27-05-2015 to 2611-2015. Sample size: 620 (310 in each group) were enrolled in the study after fulfilling inclusion criteria. Sampling technique: Non-Probability Consecutive Sampling. Results: 620 patients were enrolled in this study. Mean age of study population was 28.31 + 6.45 (Table I). 298 (48.1%) were male and 322 (51.9%) were female. Patients were divided into group A and Group B. Group A received rifaximin and group B received placebo. In group A, improvement in IBS symptoms with Rifaximin was noted in 171 (55.1%) as compared to 90 (29.03%) in group B (p-value <0.0001). Conclusion: Rifaximin is effective in treatment of IBS without constipation. Prescribing rifaximin should be considered in treatment of IBS patients as it provides a promising treatment option which is cost effective and has fewer side effects.