磷和钾对巴基斯坦西北部向日葵生长、产量的交互效应

Potassium (K) and phosphorus (P) applications improve growth, increase yield and yield components of sunflower (Helianthus annuus L.) on K and P deficient soils in Northwest Pakistan. A field experiment was conducted using sunflower cv. Hysun-33 at the New Developmental Research Farm of KPK Agricultural University, Peshawar, Pakistan, during summer 2006. The experimental design was a randomized complete block in split plot arrangements, with six levels of K (0, 25, 50, 75, 100, and 125 kg K ha^-1) as main plots and four levels of P (0, 45, 90, and 135 kg P ha^-1) as sub-plots with three replications. Sunflower yield and yield components responded positively to K and P fertilization but the magnitude of response varied with the levels of K and P. Days to flowering and maturity, grains per head, 1000-grain weight, shelling percentage, and grain yield increased tremendously in the K and P-fertilized plots as compared to the control with no K and P applied. The combined application of 100 kg K and 45 kg P ha^-1 significantly increased yield components, grain yield, harvest index, and shelling percentage of sunflower, suggesting that 100 kg K ha^-1 in combination with 45 kg P ha^-1 could maximize productivity of sunflower planted after wheat on the K and P deficient soils in the study area.     

Quality and Crop Yield Potential of Moderately Degraded Alfisols Under Different Nutrient Inputs and Cropping Patterns

Crop performance on degraded soil needs special management practices to overcome soil quality limitations. In a 2-year(from summer 2006 to winter 2007–2008) field trial on a moderately degraded Alfisol in Swabi District(34°7′12′′N, 72°28′20′′E), Pakistan,the effects of three cropping patterns, cereal-cereal(CC), cereal-legume(CL), and cereal-cereal and legume intercrop(CLI), were tested in main plots under four fertilization treatments in sub-plots, including no fertilization(control), farmers' practice(FP, 60:45 kg ha~(-1) N:P_2O_5), recommended dose(RD, 120:90:60 kg ha~(-1) N:P_2O_5:K_2O), and integrated nutrient management(INM, 20 t ha~(-1) farmyard manure integrated with 50% N, 100% P, and K of recommended dose), using a split-plot randomized complete block design. The performance of CL was superior than CC in plant height, leaf area index(LAI), cob length, grain yield, biological yield, and grain protein(8%, 26%, 8%, 5%, 10%, and 8% increases, respectively), while CLI confirmed significant improvement only in LAI(25%) over CC. Response to nutrient inputs from all sources was in the order of INM RD FP control, and the maximum net economic return by INM(23% and 2.5 times higher than RD and FP, respectively) indicated severe deficiency of both macro-and micro-nutrients in the soil as well as degraded physical properties. Increases in soil organic matter, total N, total mineral N, available P and K, total porosity, and available water-holding capacity by 6%, 34%, 24%, 50%, 13%, 5%, and 7%, respectively, and decrease in soil bulk density by 4% after four crop seasons indicated optimistic changes in soil quality as a result of the combined effects of fertilization from organic and inorganic sources and legumes within crop rotation. This study suggests that keeping the soil covered under cereal-legume rotation crops all year round and treatment with INM(50% N from organic source and 50% from inorganic source) are the best management practice for sustained production on degraded Alfisols.     

Biology of milk thistle (Silybum marianum) and the management options for growers in north-western Pakistan

Milk thistle ( Silybum marianum ) is cultivated as a medicinal plant but it also can be a troublesome weed. It is an annual or biennial herb that prefers high rainfall and fertile soils. Milk thistle has become a widespread weed in north-western Pakistan, where it causes yield reductions ≤37% in wheat and poses harvesting problems due to its thorny nature. Shortcomings in cultural practises, such as a low crop seed rate, wide row spacing, broadcast fertilizer, and limited crop rotation have contributed to milk thistle becoming a severe weed problem for farmers in this region. This paper reviews the biology of milk thistle and discusses the possible management options for its control, considering the socioeconomic conditions of farmers in Pakistan.     

玉米铬毒性研究：氧化损伤、渗透调节物质积累、抗氧化防御以及铬的吸收

Agricultural production systems are immensely exposed to different environmental stresses in which heavy metal stress receives serious concerns. This study was conducted to explore the deleterious effects of different chromium(Cr) stress levels, i.e., 0, 30, 6090, 120, and 150 μmol L-1, on two maize genotypes, Wandan 13 and Runnong 35. Both genotypes were evaluated by measuring their growth and yield characteristics, Cr accumulation in different plant tissues, alterations in osmolyte accumulation, generation o reactive oxygen species(ROS), and anti-oxidative enzyme activity to scavenge ROS. The results showed that Cr stress decreased the leaf area, cob formation, 100-grain weight, shoot fresh biomass, and yield formation, while Cr accumulation in different maize tissues was found in the order of roots leaves stem seeds in both genotypes. The increased Cr toxicity resulted in higher free proline soluble sugars and total phenolic contents, and lower soluble protein contents. However, enhanced lipid peroxidation was noticed in the forms of malondialdehyde, hydrogen peroxide(H2O2) and thiobarbituric acid reactive substance accumulation, and electrolyte leakage. The hyperactivity of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, especially glutathione peroxidase and glutathione reductase indicated that these anti-oxidative enzymes had a central role in protecting maize from Cr toxicity, especially for Wandan 13. Moreover, higher uptake and less translocation of Cr contents into the grains of Wandan 13 implied its importance as a potential candidate against soil Cr pollution.     

SATURATION PERCENTAGE AS A MEASURE OF SOIL TEXTURE IN THE LOWER INDUS BASIN

The saturation percentage is related to the mechanical constituents of a soil: and is therefore a quantitative expression of soil texture. Profiles may be described in terms of the S.P.; thus Maps may be drawn showing quantitative changes in texture, and associated statements of the reliability of an S.P. estimate and the probable error of the position of a textural contour be made. Decomposition of the calcium carbonate component should be avoided in routine soil survey work.     

在含盐新成土上施加有机肥和化学改良剂对土壤性质和作物产量的影响

A field experiment was conducted for two consecutive years in a farmer‘s field at Haji Mora Village, Dera Ismail Khan (D.I. Khan) in the Northwest Frontier Province (NWFP) of Pakistan to compare various management practices, such as the effect of various organic manures and gypsum in a rice-wheat cropping system on a saline-sodic Entisol (Zindani soil series). The treatments consisted of 1) a control (rice-wheat), 2) gypsum, 3) farmyard manure (FYM), 4) berseem (Trifolium alexandrinum L.) as green manure (GM), and 5) dhancha (Sesbania sp.) as GM. All treatments increased yields of both rice and wheat significantly (P (0.01) over the control, with the green manure treatments proving more economical than the others; while they decreased pH, electrical conductivity (EC), and sodium adsorption ratio (SAR) of the soil. Saturation percentage and available water of the soil were raised for all treatments due to an increase in organic matter content of the soil.     

Effects of nitrofurans on adrenal cortical tissue in chickens

In chicken adrenal glands, aspartate transaminase (AST) activity is concentrated in the adrenal cortical cells. Administration of a bolus dose of furazolidone (200 mg/kg) to the birds produced a decrease in AST activity in the adrenal glands and a general disorganization in the ultrastructure of the adrenal cortical cells. Many adrenal cortical mitochondria appeared to be moribund, being swollen, without cristae or apparently empty. These effects preceded atrophy of the adrenal cortical tissue, which was most marked in the central part of the adrenal glands. The atrophy was still present after 12 weeks, and it is therefore suggested that nitrofurans may be useful in the treatment of Cushing's disease in other animal species. When furazolidone or furaltadone was given in the diet at therapeutic levels, blebs of an electron-dense substance developed in adrenal cortical mitochondria and AST activity in the adrenal glands was reduced. These effects were found to be reversible, and the treatments did not produce atrophy of the adrenal cortical tissue.     

INTERACTION OF BTPYRIDYLIUM HERBICIDES WITH ORGANO-CLAY COMPLEX

The adsorption of diquat (1,1′-ethylene-2,2′-bipyridylium dibromide) and paraquat (1, 1′-dimethyl-4,4′-dipyridylium dichloride) by an organo-clay complex has been investigated. Paraquat was adsorbed by the organo-clay complex in greater amounts than was diquat. Infrared studies suggest the formation of charge-transfer complexes between diquat or paraquat and the organo-clay complex. Organic matter upon interaction with clay may facilitate the adsorption of diquat and paraquat on clay minerals in soil.     

Total sulphur amino acid requirement and cystine replacement value for fingerling rohu,Labeo rohita: effects on growth,nutrient retention and body composition

Two feeding experiments were conducted to quantify the total sulphur amino acid (TSAA) requirement and replacement value of cystine for methionine for fingerling Labeo rohita. In Experiment I, isonitrogenous (380 g kg^?1 CP) and isocaloric (17.90 kJ g^?1 GE) amino acid test diets with graded levels of methionine (4, 6, 8, 10, 12, 14 g kg^?1 dry diet) and 0.4 g kg^?1 cystine were fed to fish (4.62 ± 0.2 cm; 0.66 ± 0.1 g) and methionine requirement determined by analysing absolute weight gain (AWG) (5.48), feed conversion ratio (FCR) (1.26), protein retention efficiency (PRE%) (39%) and energy retention efficiency (ERE%) (85%) data which were best at 10 g kg^?1 methionine of dry diet. In Experiment II, six diets with different ratios of L‐cystine and L‐methionine on equimolar sulphur basis were fed to fish (4.71 ± 0.1 cm; 0.69 ± 0.2 g) under identical conditions. Maximum AWG (5.58), best FCR (1.24), PRE (41%) and ERE (86%) in fish fed Diet IV indicated cystine replacement value to be 40%. On the basis of the broken‐line and second‐degree polynomial regression analyses of results obtained in Experiments I and II, it is concluded that inclusion of TSAA in the range of 25.2–31.31 g kg^?1 of protein is optimum of which 33–39% could be spared by cystine.