安徽沿江平原区播期对稻麦周年产量、生育期及温光资源利用的影响

研究了安徽沿江平原稻区不同播期对稻麦周年产量、生育期及温光资源利用的影响,以为科学选用稻麦模式适宜水稻品种类型提供参考。结果表明,播期对不同类型水稻产量影响大小表现为迟熟中籼>中熟中粳>早熟晚粳>迟熟中粳>中熟晚粳;随播期推迟,迟熟中籼、早熟晚粳和中熟晚粳水稻产量均显著下降,播期对中熟中粳、迟熟中粳产量的影响则不明显。不同类型水稻品种与适播期春小麦接茬周年产量高低表现为“迟熟中籼稻-春小麦”>“中熟晚粳稻-春小麦”>“迟熟中粳稻-春小麦”>“早熟晚粳稻-春小麦”>“中熟中粳稻-春小麦”。在稻麦不同种植模式中,5月20日前播种的“迟熟中籼稻-春小麦”模式周年温光资源利用效率最高,较目前6月9日播种的“早熟晚粳稻-春小麦”模式的周年温光生产效率提高16.26%以上、周年光能利用效率提高18.06%以上。     

AGRONOMIC EFFICIENCY AND PROFITABILITY OF P-FERTILIZERS APPLIED AT DIFFERENT PLANTING DENSITIES OF MAIZE IN NORTHWEST PAKISTAN

The use of appropriate source of phosphorus (P) fertilizer at different planting densities has considerable impact on growth, grain yield as well as profitability of maize (Zea mays L). Field experiment was conducted in order to investigate the impact of P sources [(S₀ = P not applied, S₁ = SSP (single super phosphate) S₂ = NP (nitrophos), and S₃ = DAP (diammonium phosphate)] on maize growth analysis, yield and economic returns planted at different planting densities (D₁ = 40,000, D₂ = 60,000, D₃ = 80,000, and D₄ = 100,000 plants ha^?1) at the New Developmental Agricultural Research Farm of Khyber Pakhtunkhwa Agricultural University, Peshawar, Pakistan, during summer 2006. This paper reports the profitability data with two objectives: 1) to compare agronomic efficiency and profitability of P-fertilizers, and 2) to know whether plant densities affect agronomic efficiency and profitability of P-fertilizers. Application of DAP and SSP resulted in higher partial factor productivity (PFP) (63.58 and 61.92 kg grains kg^?1 P), agronomic efficiency (AE) (13.01 and 13.71 kg grains kg^?1 P) and net returns (NR) (Rs. 16,289 and 16,204 ha^?1), respectively, while NP stood at the bottom in the ranking with lower PFP (57.16 kg grains kg^?1 P), AE (8.94 kg grains kg^?1 P) and NR (Rs. 4,472 ha^?1). Among the plant densities, D₃ stood first with maximum PFP (69.60 kg grains kg^?1 P), AE (18.21 kg grains kg^?1 P) and NR (Rs. 21,461 ha^?1) as compared to other plant densities. In conclusion, the findings suggest that growing maize at D₃ applied with either SSP or DAP is more profitable in the wheat-maize cropping system in the study area.     

The effects of triacontanol on seedling growth and polyphenol oxidase activity in dark and light growth lettuce

The present study was designed to study the effects of various concentrations (0.00; 0.01, 0.10 and 1.00‐mg/ml) of triacontanol on root, stem and leaf growth and polyphenol oxidase activity in each respective tissue; in Grand Rapids and Great Lakes varieties of eleven‐day‐old dark and light grown lettuce seedlings.

Root, stem and leaf growth was less than in non‐triacontanol‐treated Grand Rapids seedlings in both TC‐treated dark and light exposed seedlings. With respect to Great Lakes seedlings, all dark‐grown roots exhibited greater growth than the corresponding untreated control. Light‐grown Great Lakes roots treated with 0.01‐mg/ml and 1.0‐mg/ml or triacontanol respectively, grew more than control or 0.1‐mg/ml triacontanol‐treated seedlings. Both dark and light‐grown triacontanol‐treated stem and leaf tissues of Great Lakes seedlings all produced less growth than the untreated controls.

The Grand Rapids variety had less polyphenol oxidase activity in both dark and light‐grown root and stem tissues than in untreated controls; however, both dark and light‐grown leaf tissue, treat ed with 0.01‐mg/ml and 1.0‐mg/ml of triacontanol respectively exhibited more polyphenol oxidase activity than 1.0‐mg/ml triacontanol ‐treated or untreated control tissues.

TC treatment of 0.1‐mg/ml caused no enhancement of PPO activity in dark or light‐grown root, stem and leaf tissues of Great Lakes tissue, however, seedlings treated with a concentration of 0.01‐mg/ml TC exhibited more PPO activity than non‐TC‐treated controls.     

Light‐induced reduction of FE3+ as related to causes of chlorosis in cotton

In growth chambers, cotton (Gossypium hirsutum L. genetic selection ‘M8') was grown in a synthetic growth medium under four light regimes: low pressure sodium (LPS), LPS + Incandescent (Inc), cool white fluorescent (CWF) and CWF + Inc lamps at 22 C under LPS lamps. Less chlorosis developed at 26 C than at 22 C and less under LPS + Inc than under LPS lamps. All plants were green under CWF and CWF + Inc light. Green and chlorotic plant tissue contained about the same concentrations of Fe. The proposed hypothesis was that chlorotic tissue’ contained less Fe²⁺ than green tissue. Chlorotic leaves treated with FeSO₄ turned a green color. Enough CWF + Inc light passed through an intact leaf to reduce Fe³⁺ to Fe²⁺ in vitro. Also in vitro, Fe³⁺ was reduced by CWF, by Inc, but not by LPS light. The amount of Fe³⁺ reduced during an illumination period was directly proportional to the quantity of light used. In vitro, citrate and malate enhanced Fe³⁺ reduction, whereas phosphate, pyrophosphate, OH^‐, Cu²⁺, Ni²⁺, Mn²⁺, Zn²⁺, and F^‐ all inhibited Fe³⁺ reduction by light. Orthophosphate was about 8 times as effective as organic P in decreasing Fe³⁺ reduction. Citrate largely alleviated the inhibitory effects of Pi and pH (up to pH 6). The data also provide a possible explanation of a role for many of the elements known to induce or aggravate Fe chlorosis (inhibit Fe³⁺ reduction). Quantity and quality of light apparently play key roles in plant growth as related to reduction of Fe³⁺ to Fe²⁺ in plant tops.     

Influence of photosynthetically active radiation levels and fertilizer sources on production and acclimatization of Brassaia actinophylla endl. 1/

Production light levels [1900, 1140 and 380 μE˙m^‐2 ˙s^‐1 photosynthetically active radiation (PAR)] and fertilizer treatments [Osmocote (18N‐3P‐10K) 12 g/15 cm pot, soluble. (20N‐6P‐17K) 480 ppm N weekly and combination of soluble 240 ppm N weekly plus Osmocote 6 g/pot] influenced growth parameters and elemental tissue content of Brassaia actinophylla in a 3×3 factorial experiment. Growth index, chlorophyll content and plant grade were greater in plants grown under medium and low PAR intensities (1140 and 380 μE˙m^‐2 ˙s^‐1) and when produced with the Osmocote fertilizer treatment. Inter‐nodal length decreased as production PAR levels increased. Analysis of leaf tissue indicated that decreasing PAR intensities produced an increase in N, P and K and a decrease in Mg. Calcium was unaffected.     

Response of pepper plants to NO3:NH4 ratio and light intensity

Pepper plants were hydroponically grown in a growth chamber with two levels of light intensity (300 and 240 w/m² ) and two N0₃:NH₄ ratios (100:0 and 80:20). Plants supplied with both N forms (80:20) under high light conditions showed a decrease of nutrient uptake and produced low plant weight and yield compared to the all NO₃ treated plants. By contrast, plants receiving both N forms (80:20) with light reduced over 25% showed a growth and yield slightly superior to plants supplied with N0₃ as sole source of N. This suggests a significant light intensity‐N form interaction that favors all NO₃ nutrition for pepper at high light intensities.     

Interactive Effects of Nitrogen Source and Salinity on Growth Indices and Ion Content of Indian Mustard

ABSTRACT

The interactions between salinity and different nitrogen (N) sources nitrate (NO₃ ^?), ammonium (NH₄ ⁺), and NO₃ ^? + NH₄ ⁺ were investigated on Indian mustard (Brassica juncea cv. RH30). Treatments were added to observe the combined effect of two salinity levels (8 and 12 ds m^{? 1}) and three nitrogen sources (NO₃ ^?, NH₄ ⁺, and NO₃ ^? + NH₄ ⁺) on different growth parameters and mineral composition in different plant parts, i.e., leaves, stem, and root. Salinity has been known to affect the uptake and assimilation of various essential nutrients required for normal growth and development. Different growth parameters, i.e., leaf area, dry weight of different plant parts, absolute growth rate (AGR), relative growth rate (RGR), and net assimilation rate (NAR) declined markedly by salinity at pre-flowering and flowering stages. All growth indices were less sensitive to salinity (12 d s m^{? 1}) with the nitrate form of nitrogen. It is pertinent mention that a high dose (120 kg ha^{? 1}) of nitrogen in ammonium form NH₄ ⁺, acted synergistically with salinity in inhibiting growth. Plants fed with combined nitrogen (NO₃ ^? + NH₄ ⁺) had an edge over individual forms in ameliorating the adverse effects of salinity on growth and yield. Under salt stress, different nutrient elements such as N, phosphorus (P), potassium (K⁺), and magnesium (Mg^{2 +}) were decreased in different plant parts (leaves, stem, and root). The maximum and minimum reduction was observed with ammoniacal and combined form of nitrogen, respectively, while the reverse was true of calcium (Ca^{2 +}), sodium (Na⁺), chloride (Cl^?), and sulfate (SO₄ ^2?) at harvest. Nitrogen application (120 Kg ha^{? 1}) in combined form had been found to maintain highest concentrations of N, P, Mg^{2 +}, and Ca^{2 +} along with reduced concentrations of Na⁺, Cl^?, and SO₄ ^{2 ?}. However, reverse was true with ammoniacal form of nitrogen.     

On artificial humic acids

I. Absorption Spectra of Some Artificial Humic Acids

It is a well known fact that numerous dark brown or black and amorphous substances cap be produced from organic compounds by purely chemical processes. Some of them are called artificial humic acids, and have been used as a model of soil humic acids by many workers. But it is doubtful whether such artificial humic acids are considered to be a model of soil humic acids, even if there can be found any similarities in their properties. However it may be an useful method for the study of humus formation to compare artificial humic acids with soil humic acids, and to make efforts to find a good model or to prepare artificial humic acids comparable to soil humic acids under laboratory conditions. For this purpose, first of all, the author prepared artificial humic acids from glucose, hydroquinone and lignin, and their absorption spectra were determined.     

Bacteriological studies on the mineralization of organic nitrogen in paddy soils

In this report we studied the effects of mechanical grinding of paddy soils on nitrogen mineralization and bacterial number when soils were incubated under a submerged condition after grinding.

Nitrogen mineralization was increased by grinding soil samples as compared with those without grinding. The value of (Nd-Nu)/Nu, where Nd is the amount of ammonia-nitrogen formed by incubation of disrupted samples and Nu those of the undisrupted soils, was in good correlation with clay/humus ratio.

Although significant difference was not observed between the number of aerobic bacteria with undisrupted and disrupted soil samples, higher anaerobic bacterial numbers were found with disrupted than with undisrupted ones.

A significant correlation was also obtained between the amounts of nitrogen mineralization increased by the grinding of soil and the numbers of anaerobic bacteria.     

红麻轻质阻燃人造板的研制

本文研究了红麻轻质阻燃板的生产技术,产品理想的生产工艺参数为:阻燃剂用量14%、成形压力4.0MPa、胶粘剂用量10%、热压时间为60s.mm-1热压温度120℃。产品的力学性能和阻燃性能指标如下:静曲强度≥31.85MPa;密度≤0.52g.cm-3;氧指数41%～50%;2分钟热释放率≤80kW.min.m-2,达到了相关标准的要求。