人工模拟降雨条件下不同雨强、坡度对紫色土坡面产流的影响

[目的]研究不同降雨强度和坡度对紫色土坡面产流过程的影响,为紫色土区域的水土流失防治提供科学依据。[方法]基于室内人工模拟降雨试验开展研究。[结果]不同雨强和坡度下的产流过程可大致分为"下凹"型和"上凸"型,且分别可以用指数函数和对数函数描述。随着雨强和坡度的增大,产流时间逐渐减小,产流过程逐渐趋于一致,坡面径流量逐渐增加。坡度和雨强对径流总量的贡献率有着对比消长的关系,小雨强下(雨强为33和54mm/h),坡度是坡面径流总量的主要贡献因子,随着雨强增大(雨强为94和125mm/h),雨强为坡面径流总量的主要贡献因子。[结论]坡度和雨强均为坡面侵蚀的主要影响因子,随着坡度和雨强的增加,坡面侵蚀更加剧烈,主要侵蚀因子也由坡度转变为雨强。     

Zinc and Boron Application at Different Phenological Stages Alleviates Tree Growth,Fruit Yield and Quality of Sweet Orange Cv. ‘Blood Red’

The deficiency of micronutrients, particularly zinc (Zn) and boron (B) has affected vegetative growth, yield and fruit quality of sweet orange in many citrus growing areas of Pakistan. The present study was conducted in 2015 and 2016 to determine the impact of Zn and B supplementation on growth and quality of sweet orange cv. ‘Blood red’. Pre-harvest foliar application of variant Zn and B levels was done at different phenological stages of fruit growth and development, i.e., full bloom, fruit set and premature stage. Results have concluded that pre-harvest foliar application of Zn and B augmented phosphorous, Zn, B, potassium, iron, and manganese contents in leaves, particularly Zn and B content from deficient to optimal level. Moreover, the combined application of Zn and B has also significantly enhanced vegetative characters such as tree height and spread along with reproductive characters, i.e., incremented numbers of fruit, fruit weight, total soluble solids, titratable acidity and ascorbic acid contents. However, among stage comparison, outcomes depicted that foliar application of Zn and B at full bloom?+?fruit set?+?premature stage resulted in maximum production with high quality fruits.

     

Population dynamics of citrus leaf miner on different varieties of citrus in correlation with abiotic environmental factors in Sargodha District,Punjab, Pakistan

From January 2010 to December 2011, samples of leaves from citrus varieties Kinnow, Musambi and Feutral were taken from the five tehsils (administrative subdivisions) of Sargodha District in Pakistan including Sargodha, Bahalwal, Silanwalli, Sahiwal and Kotmomin, to study the population trends in citrus leaf miner (CLM), Phyllocnistis citrella (Stainton) (Lepidoptera: Gracillariidae), and its correlation with various environmental factors: (temperature, humidity and rainfall); plant morphological factors: moisture contents of leaves, leaf thickness, surface area (cm ² ), and biochemical percentage of calcium, potassium and magnesium in leaves. The maximum population of CLM was observed on Kinnow and Feutral, followed by Musambi. The effect of these factors on the larval population was 8.39- 2.30(Mg)+2.73(K)-0.398(Ca)-0.100(Temp)0.038(Humidity)+0.567(Rain)+0.07(Moist) 1.01 (Thickness)-0.022(Surface area). This equation revealed that magnesium, calcium, temperature, humidity, leaf thickness and leaf surface area are negatively correlated with larvae population, whereas potassium, rainfall and moisture are positively correlated with larvae population.     

Therapeutic Potential of Marine Bioactive Peptides against Human Immunodeficiency Virus: Recent Evidence,Challenges, and Future Trends

Acquired immunodeficiency syndrome (AIDS) is a chronic and potentially fatal ailment caused by the human immunodeficiency virus (HIV) and remains a major health problem worldwide. In recent years, the research focus has shifted to a greater emphasis on complementing treatment regimens involving conventional antiretroviral (ARV) drug therapies with novel lead structures isolated from various marine organisms that have the potential to be utilized as therapeutics for the management of HIV-AIDS. The present review summarizes the recent developments regarding bioactive peptides sourced from various marine organisms. This includes a discussion encompassing the potential of these novel marine bioactive peptides with regard to antiretroviral activities against HIV, preparation, purification, and processing techniques, in addition to insight into the future trends with an emphasis on the potential of exploration and evaluation of novel peptides to be developed into effective antiretroviral drugs.     

Genetic inferences from inter‐strain crossing for hatchability and fertility in white leghorns

1. Heritability estimates for hatchability of fertilised eggs were obtained from four White Leghorn strains and their crosses.

2. Based on the variance of the full‐sib family means, the heritability estimates for pure‐bred, cross‐bred and for the combined data were 0.lb186 ± 0.lb105, 0.lb065 + 0.lb021 and 0.lb088 + 0.lb005, respectively: the results showed absence of non‐additive genetic variance for hatchability.

3. Fertility was influenced more by sire strain than by the dam while hatchability was primarily influenced by the dam strain.

4. The sire x dam interaction effect was significant for fertility but not for hatchability.

5. Fertility was influenced by crossing two divergent strains.     

Effect of eCG dose on ovarian haemodynamics,hormonal profiles and prolificacy rate when oestrus was induced during low-breeding season in Beetal goats

The objectives of the experiment were to determine the effect of two doses of equine chorionic gonadotropin (eCG) in a standard synchronization protocol based on a short-term progesterone (P₄) priming on ovarian structures and haemodynamics, concentrations of steroid hormones and prolificacy rate when oestrus was induced during low-breeding season (LBS) in Beetal dairy goats. We hypothesized that inclusion of eCG in a short-term P₄ priming-based synchronization protocol would increase the blood perfusion to ovarian structures leading to enhance oestrous and ovulatory responses and prolificacy rate in goats. Forty-two multiparous acyclic goats were blocked by body condition and, within block, assigned randomly to receive saline as control (CON), low eCG (L-eCG; 300 IU) or high eCG (H-eCG; 600 IU) dose. Initially, a controlled internal drug release (CIDR) device was placed in the anterior vagina on d −8, followed by removal of CIDR on d −3, concurrent with the administration of PGF_2α and eCG according to their respective treatments. Goats were monitored for oestrous response. B-mode and Doppler ultrasonography was performed with 12-h interval, starting from day −3 until natural breeding (day 0), and then on days 5, 10, 15 and 20 post-breeding to monitor follicular and luteal dynamics and blood flow, respectively. Blood was sampled at 0, 12, 24, 36 and 60 h after CIDR removal to quantify plasma concentrations of estradiol-17β (E₂), whereas plasma concentrations of P₄ were assayed at days 5, 10, 15 and 20 after breeding. Pregnancy and prolificacy rates were determined at day 30 and 150 after breeding, respectively. Data were analysed with mixed-effects models, and orthogonal contrasts were used to evaluate the effect of treatment [Con vs. (½ L-eCG + ½ H-eCG)] and dose of eCG (L-eCG vs. H-eCG). Data are presented in sequence as CON, L-eCG, H-eCG (LSM ± SEM). The oestrous intensity score (152.9 vs. 182.7 vs. 186.5 ± 15.1; p = .02) was greater in eCG-treated goats as compared to CON. Administration of eCG reduced the intervals to standing oestrus (66.2 vs. 41.8 vs. 48.9 h ± 5.5; p = .05), breeding (70.2 vs. 44.4 vs. 45.4 h ± 4.5; p = .03) and ovulation (84.5 vs. 61.2 vs. 63.4 h ± 6.2; p = .05) compared with CON goats. The mean growth rate of pre-ovulatory follicle was greater (1.11 vs. 1.49 vs. 1.45 mm ± 0.08; p = .01) in eCG-treated goats resulting in an increased diameter of pre-ovulatory follicle (6.27 vs. 7.20 vs. 7.31 mm ± 0.07; p < .01) and corpora lutea (6.75 vs. 8.26 vs. 8.07 mm ± 0.42; p = .04) than CON. The mean follicular blood flow did not differ among treatments; however, the mean luteal blood flow was greater in L-eCG-treated goats (0.81 vs. 1.61 vs. 1.07 cm² ± 0.12; p = .001). The mean concentrations of E₂ (4.03 vs. 5.21 vs. 4.78 pg/ml ± 0.42; p = .04) and P₄ (4.85 vs. 6.39 vs. 6.22 ng/ml ± 0.34; p = .04) were greater in eCG-treated goats. The twinning rate did not differ between treatments; nevertheless, prolificacy rate was greater (p = .04) in L-eCG-treated goats. Collectively, our data suggest that the administration of eCG improves the induction of oestrous and ovarian dynamics. Administration of L-eCG enhances prolificacy rate, therefore, a low dose of eCG might be practically beneficial to improve reproduction during LBS in acyclic Beetal dairy goats.     

Using Growth and Ionic Contents of Wheat Seedlings as Rapid Screening Tool for Salt Tolerance

High germination percentage with vigorous early growth is preferred for harvesting good wheat stand under saline soils. Therefore, an attempt for rapid screening of wheat genotypes for salt tolerance was made in this study. Eleven wheat genotypes including salt tolerant check Kiran-95were subjected to salinity (120 and 160 mMNaCl) along with non-saline control. Results showed a gradual decrease in seed germination and restricted seedling growth in tested wheat genotypes in response to increasing NaCl concentration in nutrient solution. Among the genotypes, NIA-AS-14-6 and NIA-AS-14-7 exhibited more sensitivity towards the salt stress at the germination stage but NIA-AS-14-6 performed quite satisfactorily later on at the seedling stage. Wheat genotypes NIA-AS-14-2, NIA-AS-14-4, NIA-AS-14-5, NIA-AS-14-10, and Kiran-95 showed better performance in term of root-shoot length, plant biomasses (fresh and dry), K⁺:Na⁺ ratio with least Na⁺ content, and high accumulation of K⁺ at higher levels of NaCl stress. On the basis of overall results, the categorization of genotypes was carried out as sensitive, moderately tolerant, and tolerant. Wheat genotypes NIA-AS-14-2, NIA-AS-14-4, NIA-AS-14-5, NIA-AS-14-10, and Kiran-95 grouped as tolerant, moderately salt tolerant group comprised of NIA-AS-14-1, NIA-AS-14-3, NIA-AS-14-6, and NIA-AS-14-8, whereas, NIA-AS-14-7 and NIA-AS-14-9 were found sensitive to salt stress. Principal component analysis revealed that components I and II contributed 70 and 16.5%, respectively. All growth parameters are associated with each other except RDW. In addition to growth traits, low Na⁺ and improved K⁺ content with better K⁺:Na⁺ ratio may be used for screening of salt tolerance in wheat as potential physiological criteria.     

Amelioration of cadmium stress in gladiolus (Gladiolus grandiflora L.) by application of potassium and silicon

Gladiolus corms were grown in media contaminated with cadmium (Cd) (50 mg kg^?1) and supplemented with silicon (Si) and potassium (K). The role of Si and K for mitigation of Cd toxicity was evaluated. Cd-induced stress generated significantly increased level of oxidative stress markers including hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) in gladiolus. The application of K and Si improved the production of protein and proline in the treated plants. Moreover, K and Si supplemented plants exhibited an improvement in the activity of antioxidant enzymes and a reduction in the level of MDA, H₂O₂ and Cd uptake under Cd stress. Application of K and Si also enhanced the uptake of mineral nutrients including calcium (Ca), magnesium (Mg), manganese (Mn), sulfur (S) and K. The plants supplemented with K and Si exhibited a higher amount of total phenolics and flavonoids. The combined effect of Si and K was more pronounced regarding beneficial effects on gladiolus plants compared to individual effect of these elements under Cd stress. The current research reveals that Si and K may improve gladiolus growth by decreasing the oxidative stress and Cd uptake and by increasing the activity of antioxidant defense enzymes, the quantity of secondary metabolites and plant nutrition.     

Methylene Blue Stainability of Root-Tip Protoplasts as an Indicator of Aluminum Tolerance in a Wide Range of Plant Species, Cultivars and Lines

We previously developed a new simple technique of methylene blue (MB) staining for the discrimination of aluminum (Al)-tolerant protoplasts from 4 plant species (rice, oats, maize and pea). The objectives of the present study were to confirm the applicability of this technique to a wider range of plant species, cultivars and lines, and to identify a common strategy for the early stage of Al tolerance. A total of 10 plant species, two Brachiaria spp., two Oryza spp., buckwheat, maize, pea, triticale, wheat and barley, corresponding to 18 different plant samples (species, cultivars, and lines), were used. Al tolerance (relative net root elongation of the longest root), which was screened at 20 μM AICI₃ in 0.2 mM CaCl₂ (pH 4.9) for 24 h, ranged widely from 10 to 88. Among cultivars and lines within the same species, Al accumulation in the root tip portion was higher in Al-sensitive plants, corresponding to more severe permeabilization of the plasma membranes (PM). Protoplasts isolated mainly from the epidermis, and outer and central parts of the cortex were stained to different degrees by MB, and the blue color was observed both on the surface and inside the protoplasts. Color pictures obtained after staining for 3 min with 0.1% MB were analyzed by Image Hyper II. The ratio of the heavily stained area at threshold 95 to the entire area stained with MB at threshold 125 was defined as MB stainability. MB stainability was negatively correlated with Al tolerance ( y = 48.6e^{−0.02 x} , R ²= 0.676**) suggesting the common importance of permeation characteristics of PM, in addition to PM negativity for Al tolerance in a wide range of plant species, cultivars and lines. Analysis of the PM lipid composition was proposed as an important topic for future studies on the negativity and permeation of PM.