Muhammad Arshad Javed

Genetic analysis of quantitative traits in rice (Oryza sativa L.) exposed to salinity

Abstract The release of rice cultivars with improved performance in saline environments is reliant on an understanding of the genetic control of plant and panicle characters in plants exposed to salinity. The regulation of agro-physiological characters of rice plants grown in a saline environment was thus investigated. A complete diallel cross was prepared from 8 parental rice accessions with a range of tolerances to salinity. F1 hybrids and parents were grown in saline-sodic soil in artificially constructed salinity blocks. At maturity, the plant height, productive tiller number per plant, panicle length, primary branch number per panicle, panicle fertility, time to maturity, shoot dry weight, shoot Na, Ca, and K concentrations, and paddy yield were recorded. Additive and dominant genetic effects contributed significantly to the total heritable variation observed for plant height, panicle length, and sodium and potassium shoot concentrations. Additive genetic effects were important for the expression of variation of productive tiller number per plant and the number of primary branches per panicle, while dominant genetic effects were important for the expression of variation of the number of days to maturity. Plant height and primary branch number per panicle are traits that may be readily improved by selection in saline environments.

Evaluation of Trichoderma isolates as potential biological control agent against soybean charcoal rot disease caused by Macrophomina phaseolina

ABSTRACT Macrophomina phaseolina (Tassi) Goid remains the prevailing causal agent of charcoal rot disease that significantly suppresses the yield of a variety of oilseed crops. Its wide host range and ability to survive under arid conditions, coupled with the ineffective use of fungicides against it, have spurred scientific endeavours for alternative avenues to control this phytopathogen. Hence, the present study aimed to provide empirical evidence of the efficacy of three fungal isolates (T2, T10 and T12) of Trichoderma harzianum as biological control agents against charcoal rot in soybean (Glycine max L.). The results of the in vitro studies revealed that all three fungal isolates significantly inhibited the growth of M. phaseolina phytopathogen, with T12 showing considerably higher inhibition effect than T2 and T10 isolates. T12 inhibited the growth of M. phaseolina in the dual culture (72.31%) and volatile production (63.36%) assays, and the hyperparasitism test indicated cell lysis following the interactions with T12 mycelia. T12 isolate was mostly effective in field experiments, observable in the attained minimum plant disease indices both in the soil incorporation (11.98%) and seed inoculation (5.55%) treatments, in comparison to isolates T2 and T10. Moreover, the stem and root lengths, as well as the seed weight, were considerably increased, as compared to the control. Hence, the findings reported in the present study supported the applicability of T12 isolate as possible alternative to fungicides for the control of charcoal rot in soybean.

Microbial Effects on Seed Germination in Malaysian rice (Oryza sativa L.)

Seed germination is the basis of plant growth as it determines the viability of rice. A laboratory experiment was conducted to observe the effect of microbial inoculation on seed germination and seedling growth of two lowland rice varieties (Mahsuri and Sri Malaysia 1) and two upland rice landraces (Panderas and SK-1). The experiment was conducted using wet filter paper in Petri dish. The design of the experiment was completely randomized (CRD) with three replicates. Three selected growth promoting microbes Nitrosomonas europaea , Rhodopseudomonas palustris and Acinetobacter sp . were used in the experiment. Seeds inoculated with those microbes and the Petri dish were kept in the dark for five days and subsequently subjected to light condition for another five days. The seed germination and other related attributes were measured. Significance and non significant differences were observed for growth parameters and germination traits, respectively. Among the microbes, Nitrosomonas europaea and its combination performed better in root length and combination of Rhodopseudomonas palustris and Acinetobacter sp . promotes the best growth of shoot. Nitrosomas europaea has shown to play a major role in the germination rate growth in all varieties. It is therefore concluded that growth promoting microbes may have positive effects on germination of rice seeds.

Development of Novel Protocol to Al3+ Stress Tolerance at Germination Stage in Indica Rice through Statistical Approaches

Rice production is decreasing by abiotic stresses like heavy metals. In such circumstances, producing food for growing human population is a challenge for plant breeders. Excess of Al3+ in soil has become threat for high yield of rice. Improvement of crop is one of potential solution for high production. The aim of this study was to develop the new method for optimization of Al3+ toxicity tolerance in indica rice at germination stag using two-way ANOVA and Duncans multiple-range test (DMRT). Seeds of two indica rice cultivars (Pokkali and Pak Basmati) were exposed in different concentrations (control, 5 mM, 15 mM, and 20 mM) of Al3+ toxicity at pH 4 ±0.2 for two weeks. Germination traits such as final germination percentage (FG%), germination energy (GE), germination speed (GS), germination index (GI), mean time of germination (MGT), germination value (GV), germination velocity (GVe), peak value of germination (GPV), and germination capacity (GC) and growth traits such as root length (RL), shoot length (SL), total dry biomass (TDB), and germination vigour index (GVI) were measured. To obtain the maximum number of significance (≤ 0.01%) parameters in each concentration of Al3+ toxicity with control, two-way ANOVA was established and comparison of mean was done using DMRT. The results showed that 5 mM, 10 mM, and 15 mM have less significant effects on the above-mentioned parameters. However, 20 mM concentration of Al3+ produced significant effects (≤ 0.01%). Therefore, 20 mM of Al3+ is considered optimized limit for indica cultivars (Pokkali and Pak Basmati).

STABILITY ANALYSIS OF SOIL SLOPE IN SWABI, PAKISTAN

In this study, slope stability analysis for a particular type of soil in Swabi area was carried out using the method of slices. Gravity load and seismic load were considered in the stability analysis. SLOPE/W and SIGMA/W software of Geo studio package were used for analysis under both dry and completely saturated conditions. Pseudo-static approach was used for the seismic stability analysis. The peak ground acceleration value for stability analysis was obtained from the seismic hazard analysis. Two soil slope conditions were considered, and one was found in critical condition. Retaining wall, Soil nails and ground anchors were assumed in the analysis for stability of slope with critical condition. Peak ground acceleration value of 0.235g is determined with site specific deterministic seismic hazard assessment approach. The maximum displacement in the soil slopes with retaining wall, soil nails, and ground anchors are 0.0220, 0.01665 and 0.01529 feet respectively. Results showed that using ground anchors have a factor of safety 1.165 and both the horizontal and vertical deformation values are within the limit. Based on results, ground anchors technique was found to be a suitable method for slope stability in Swabi.