QTLs associated with tolerance of flooding during germination in rice (O<Emphasis Type="Italic">ryza sativa</Emphasis> L.)

Direct seeding of rice is increasingly being practiced in both rainfed and irrigated areas because of labor shortage for transplanting and opportunities for crop intensification. However, poor crop establishment remains a major obstacle facing its large-scale adoption in areas prone to flooding. Screening of over 8,000 gene bank accessions and breeding lines identified a few tolerant genotypes. One of these, Khao Hlan On, was selected for mapping QTLs associated with tolerance using a backcross population with IR64 as a recurrent parent. Survival of BC₂F₂ lines varied from 0 to 68%, and averaged about 28%. A linkage map of 1475.7 cM with an average interval of 11.9 cM was constructed using 135 polymorphic SSRs and 1 indel marker. Five putative QTLs were detected, on chromosomes 1 (qAG-1-2), 3 (qAG-3-1), 7 (qAG-7-2), and 9 (qAG-9-1 and qAG-9-2), explaining 17.9 to 33.5% of the phenotypic variation, and with LOD scores of 5.69–20.34. Khao Hlan On alleles increased tolerance of flooding during germination for all the QTLs. Graphical genotyping of the lines with highest and lowest survival verified the detected QTLs that control tolerance and some QTLs co-localize with previously identified QTLs for traits relevant to tolerance, which warrant further studies.     

The effect of manipulations of incubation temperature on embryonic and post-hatching growth of native Saudi chickens

Embryonated egg is an ideal, environment in which to investigate the effects of incubation temperature on the development of the chick embryo. The objective of the current study were to investigate the effect of increasing the incubation temperature of chick embryo by 1.2 degrees C for 7 days (ED4 to ED11) on the body movement and mass of native saudi chick embryo. This objective was extended to examine the influence of pre-hatching temperature on post-hatching growth. Therefore, a total of 180 hatching egg of native Saudi chicken divided into two equal groups incubated at temperature 37.5 degrees C. The incubation temperature was raised to 38.7 degrees C from ED4 to ED11 in treated group before being returned to the control group incubation temperature (37.5 degrees C). The study revealed that elevating the incubation temperature of the eggs of native Saudi chicken by just 1.2 degrees C, from 37.5 to 38.7 degrees C, during embryonic days (ED) 4-11 causes significant increase in embryonic movement as demonstrated in day 8 in the chicks incubated at 38.7 degrees C together with an increase in embryonic development, the embryos incubated at higher temperature were heavier in weights and exhibit significantly longer legs than the controls in ED12 and 15. The increase in pre-hatching incubation temperature (38.7 degrees C) did not reveal any significant effects on post-hatching growth or of feed conversion efficiency.     

Submergence Tolerant Rice: SUB1’s Journey from Landrace to Modern Cultivar

Rice landraces tolerant of up to 2 weeks of complete submergence were collected from farmers’ fields in the 1950s. Success in fine mapping of SUBMERGENCE 1 (SUB1), a robust quantitative trait locus from the submergence tolerant FR13A landrace, has enabled marker-assisted breeding of high-yielding rice capable of enduring transient complete submergence. At the molecular level, SUB1 is a variable polygenic locus encoding two or three ethylene responsive factor (ERF) DNA binding proteins. All Oryza sativa accessions encode SUB1B and SUB1C at this locus. An additional ERF, SUB1A, is present at SUB1 in FR13A and other tolerant accessions. The induction of SUB1A expression by ethylene during submergence disrupts the elongation escape strategy typical of lowland and deepwater rice, by limiting ethylene-induced gibberellic acid-promoted elongation. Microarray and metabolite studies confirm that SUB1A orchestrates its effects on metabolism and growth in a submergence-dependent manner. Due to the conditional activity of SUB1A, new “Sub1” mega-varieties effectively provide submergence tolerance without apparent ill effect on development, productivity, or grain quality.     

Marker Assisted Selection for Submergence Tolerance in Rice

Yields in the irrigated rice areas have improved remarkably over the last three decades. Farmers with access to assured water supply have adopted improved varieties, resulting in higher yields and improved income in rural areas. In contrast, yields remain low in the vast rainfed areas that are associated with higher levels of poverty. A few improved varieties have spread in these areas, but abiotic stresses such as drought and submergence prevent farmers from realizing their yield potential. Stress tolerant versions of these varieties are urgently needed to improve the standard of living and stabilize household food supplies. It has been found that tolerance to a number of abiotic stresses is controlled by a few QTLs of large effect, and that incorporation of these QTLs into the high yielding varieties could make a significant impact in stabilizing the yields of these varieties in stress-prone areas （Mackiil, 2006）. Submergence tolerance provides a good example of how marker assisted selection can be very effective to develop improved varieties for the rainfed lowlands.     

Effect of soil type and soil water content levels on pupal mortality of the peach fruit fly [Bactrocera zonata (Saunders)] (Diptera: Tephritidae)

Peach fruit fly (PFF), Bactrocera zonata, is one of the most dangerous pests of horticultural crops worldwide. This pest spends part of its life cycle in the soil as pre-pupae and pupae. Therefore, the effects of soil type and soil water content levels (SWCLs) on pupal mortality rates of the PFF were studied in an attempt to use soil moisture as an abiotic management strategy for this pest. The effect of clay, loamy, and sandy soils with SWCL of 0, 10, 25, 50, 75, 90, and 100% of field capacity on three ages of PFF pupae (newly formed, 4- and 7-day-old pupae) were studied. Results demonstrated significant effects of SWCLs on pupal mortality rates of PFF. SWCL was the factor with the most remarkable effect (48.47%), meanwhile soil type had a feeble effect (0.65%). Newly formed pupae were more susceptible to SWCL levels than 7- and 4-day-old pupae. Results suggest that sustaining SWCL near 100% of field capacity significantly (p?=?0.000) suppressed PFF population; therefore it could be an important component of Integrated Pest Management against this insect species.     

Shoot and root growth of rice seedlings as affected by soil and foliar zinc applications

Abstract

The present study investigated how foliar zinc (Zn) application affects seedling growth and Zn concentration of rice grown in a Zn-deficient calcareous soil with different soil Zn treatments. Seeds were sown in soil with five rates of Zn (0, 0.02, 0.1, 0.5 and 5.0?mg kg^?1 soil) with and without foliar application of 0.5% ZnSO₄. Seedlings were harvested at 35?days and separated into (i) the youngest leaves, (ii) the remaining shoot parts and (iii) roots. In soil with no Zn supply, shoot and root dry weight of the rice seedlings were significantly increased by foliar and soil Zn treatments. Plant growth was not clearly increased in low soil Zn treatments, while at each soil Zn treatment, foliar Zn application promoted growth of plants. Plants with adequate Zn supply had the highest Zn concentrations in the youngest leaf. Foliar Zn spray improved Zn concentration of the new growth formed after foliar spraying which shows that Zn is phloem mobile and moved from treated leaves into youngest new leaves. The results indicate clearly in rice seedlings that shoot growth shows more responsive to low Zn than the root growth. The results obtained in the present study are of great interest for proper rice growth in Zn-deficient calcareous soils but needs to be confirmed in other rice genotypes.     

1H NMR-Based Metabolomics Approach in Investigating the Chemical Profile,Antioxidant and Anti-Inflammatory Activities of Gynura procumbens and Cleome gynandra

Plant Foods for Human Nutrition - Gynura procumbens and Cleome gynandra are two herbs commonly used in Malaysia to treat various ailments and are also consumed as salads (ulam) and vegetables. The...     

Identification and quantification of phenolic compounds in bambangan (Mangifera pajang Kort.) peels and their free radical scavenging activity

Phenolic compounds and antioxidant capacity of acidified methanolic extract prepared from fully ripe bambangan (Mangifera pajang K.) peel cultivated in Sarawak, Malaysia, were analyzed. The total phenolic content (98.3 mg GAE/g) of bambangan peel powder (BPP) was determined by the Folin-Ciocalteu method. BPP showed a strong potency of antioxidant activity and was consistent with that of BHT and vitamin C as confirmed by the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity and FRAP (ferric-reducing antioxidant power) assays. Gallic acid, p-coumaric acid, ellagic acid, protocatechuic acid, and mangiferin were the major compounds among the 16 phenolics that have been identified and quantified in M. pajang peels with 20.9, 12.7, 7.3, 5.4, and 4.8 mg/g BPP, respectively. Peak identities were confirmed by comparing their retention times, UV-vis absorption spectra, and mass spectra with authentic standards. The 16 phenolic compounds identified in M. pajang K. using HPLC-DAD and TSQ-ESI-MS are reported here for the first time.     

Use of Lignocellulolytic Microbial Consortium and pH Amendment on Composting Efficacy of Rice Straw

ABSTRACT

The present study was conducted at the Composting Unit, Universiti Putra Malaysia to determine the physico-chemical changes, microbial dynamics, and enzyme activities during microbial composting of rice straw at different pH conditions. Different treatments comprising of composting substrates (A), substrates with microbial consortium (B), substrates, microbial consortium, and acetic acid (C), substrates, microbial consortium, and sodium hydroxide (D) were used to enhance the composting process of rice straw. In inoculated treatments, the temperature increased rapidly to higher than 50°C by day 5 and remained above 40°C up to day 17, while in the control the temperature increased slowly and peaked (46°C) at day 9 and remained above 40°C until day 23. The results showed that biodegradation was at its maximum in microbial-infused treatments within 14–21 days as indicated by profiles of pH, reduction of C/N ratio, lignocellulolytic (lignin peroxidase, endoglucanase, and exoglucanase) enzyme activities, and lignocellulose bioconversion. After day 21, the C/N ratio of microbial-infused treatment without any pH adjustment (B) was reduced to 17.5 from an initial value of 29.2 suggesting that there were no additive effects of pH adjustment during the microbial composting of rice straw.