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171.
自20世纪80年代起,云南保山潞江坝胡椒种植面积逐渐萎缩,经调查分析,该地区冬春季节低温干旱的气候条件、管理粗放、连作障碍等导致胡椒旱衰和死亡是种植面积大幅萎缩的主要原因;作者在此基础上提出了该区胡椒产业发展的建议。 相似文献
172.
A field study was conducted for six years (1981–1986) on sandy loam soil on intercropping hedgerows of Leucaena leucocephala (Lam) de Wit. with three field crops viz. maize (Zea mays L), black gram (Vigna mungo L) and cluster bean (Cyamopsis tetragonoloba L Taub.). In treatments 1 and 2 Leucaena hedges were planted as pure crops at close (25 cm × 75 cm) and wide (25 cm × 375 cm) spacings. In treatments 3, 4 and 5 the
three field crops were intercropped between the hedgerows of Leucaena at the wide spacing, and in treatments 6, 7 and 8 the field crops were raised as pure crops. Leucaena was topped to 75 cm each time it attained a height of 175 cm.
The pure crop of Leucaena at close spacing produced an average, over the six years, of 34 t ha−1a−1 of green fodder and 9.4 t ha−1a−1 of air dry fuelwood. The Leucaena at wide spacing produced 18.9 t ha−1a−1 of green fodder and 6.3 t ha−1a−1 of fuelwood. Intercropping with field crops decreased the yield of green fodder and fuelwood. The yield of all the field
crops was less when raised as intercrops than as pure crops.
Mean maximum net returns were obtained from intercrops of Leucaena and cluster bean (Rs 3540 ha−1a−1) which were significantly higher than the returns from pure crop of Leucaena at wide spacing but similar to the returns from pure crops of cluster bean. Leucaena with maize (Rs 3273 ha−1a−1) and black gram (Rs 3125 ha−1a−1) gave significantly higher net returns over pure crops of Leucaena at wide spacing, maize and black gram.
ICRISAT = International Crops Research Institute for the Semi-Arid Tropics- Hyderabad, India.
CIAT = Centro International de Agricultura Tropical - Cali - Columbia 相似文献
173.
174.
Field trials were carried out on an Oxic Paleustalf in the humid zone of southwestern Nigeria withLeucaena leucocephala (Lam.) de Wit,Gliricidia sepium (Jacq.) Steud. andSesbania grandiflora (L.) Pers. alley cropped with maize and cowpea. The three leguminous woody species were grown in hedgerows spaced at 2 m.
Trials were carried out one year after establishment of the hedgerows using a split-plot design with four replications. TheLeucaena trial had twenty pruning combinations consisting of five pruning heights (25, 50, 75, 100 and 150 cm) and four pruning frequencies
(monthly, bi-, tri- and six-monthly). TheGliricidia andSesbania hedgerows were subjected to nine pruning intensities consisting of three pruning heights (25, 50 and 100 cm) and three pruning
intensities (monthly, tri- and six-monthly).
For the three woody species, biomass, dry wood and nitrogen yield from the hedgerow prunings increased with decreasing pruning
frequency and increasing pruning height. Biomass, dry wood and nitrogen yields were in the following orderLeucaena >Gliricidia >Sesbania.
The various pruning intensities had no effect on survival ofLeucaena plants. Pruning frequency had a larger effect than pruning height on survival ofGliricidia andSesbania plants. With monthly pruning, about 25 percent of theGliricidia and all of theSesbania plants died within six months of repeated pruning. Even with lower pruning frequencySesbania plants showed lower survival rates thanGliricidia orLeucaena.
The various pruning intensities of all the hedgerow species had more pronounced effects on the grain yield of the alley cropped
cowpea than on maize grain yield. Higher maize and cowpea yields were obtained with increasing pruning frequency and decreasing
pruning height.
IITA Journal paper number 335 相似文献
175.
The potential of allye cropping systems to sustain a high productivity with low external inputs and the reduction of maize/weed competition through weed suppression in different alley cropping and sole-cropped mulched systems was studied in Costa Rica at CATIE. Data were recorded eight years after establishment of the experiment. Plant residues ofErythrina poeppigiana trees (10 t/ha dry matter) planted at 6 by 3 m reduced weed biomass by 52%, whileGliricidia sepium trees (12 t/ha dry matter) planted at 6 by 0.5 m reduced weed biomass by 28%, in comparison to controls.Erythrina had a considerable impact on grass weeds, whileGliricidia reduced the incidence of some dicot weeds. Weed competition significantly reduced maize yield in all systems. Nevertheless weed suppression contributed to the higher maize grain yield underErythrina andGliricidia alley cropping of 3.8 t per hectare as opposed to the unmulched control yield of 2.0 t per hectare. 相似文献
176.
The potential of hedgerow intecrropping with Leucaena leucocephala was explored on vertic Inceptisols over 4 years at ICRISAT Center, Patancheru, India. The study was conducted using a systematic layout involving different alley widths ranging from 1.35 to 4.95 m and with varying distances between hedge and crops. The alleys were cropped with alternate rows of sorghum and pigeonpea. Hedges composed double Leucaena hedgerows 60 cm apart were periodically harvested for fodder. Sole crops of all components and a sorghum/pigeonpea intercrop were included in all four replications of the study.Starting in the second year, Leucaena was progressively more competitive to annual crops, causing substantial yield reduction. Competition (primarily for moisture) was most severe in narrow alleys and was greatest on pigeonpea.The growth of Leucaena was not sufficient to compensate for reduced crop yields. Land equivalent ratios (LERs) calculated on the basis of grain yield of crops and Leucaena fodder yields showed that hedgerow intercropping (HI) was advantageous over sole crops only during the first two years using wide alleys, but disadvantegeous in the last two years. LERs calculated on the basis of total dry matter indicated only a small advantage for HI (13–17 percent) over sole crops in wider (>4 m) alleys. Average returns per year from HI exceeded those of the most productive annual crop system (sorghum/pigeonpea intercropping) by 8 percent in 4.05 m alleys, and by 16 percent in 4.95 m alleys. Fodder production during the dry season was 40 percent of the annual total in these alley widths. Thus hedgerow intercropping at 4–5 m alley width is not very attractive for farmers in semi-arid India, which has 600–700 mm of annual rainfall. There is a need to examine the potential of HI in wider alleys. The merits and limitations of the systematic design are discussed. 相似文献
177.
Kazuki?NankoEmail author Norifumi?Hotta Masakazu?Suzuki 《Journal of Forest Research》2004,9(2):157-164
The raindrop size distribution of throughfall and open rainfall was monitored continuously during a rainfall event using laser raindrop-sizing instruments (LD gauges), in order to calculate the raindrop impact energy in a plantation of mature Japanese cypress (Chamaecyparis obtusa), where surface erosion at the forest floor had been a problem. Data from two rainfall events were analyzed. The LD gauges recorded qualitative raindrop size distribution, and the capture rate during each rainfall event was used to manipulate raindrop data quantitatively. Throughfall and open rainfall comparisons revealed several important differences. First, throughfall raindrops were fewer in number and larger in size than open rainfall drops. In one rainfall event, for example, throughfall raindrops were less than one-fifth as frequent as open rainfall raindrops; in addition, the maximum throughfall raindrop diameter was 6.35mm compared to 3.31mm for open rainfall raindrops. Second, throughfall raindrops that were larger than the largest open rainfall raindrops comprised 63.8% of the throughfall precipitation by volume. Third, total raindrop impact energy from throughfall was over twice that of open rainfall. Moreover, comparison of throughfall events implied that throughfall raindrops did not always have a uniform distribution between different events or among different periods of time in one rainfall event, in contrast to findings in previous studies which showed that throughfall raindrops had a uniform size distribution independent of rainfall intensity. It is possible that an abrupt transition of throughfall intensity from low to high changes the distribution of throughfall raindrops. 相似文献
178.
连续平压热压机的进展 总被引:3,自引:1,他引:3
论述了发展连续平压热压机的背景、必要性以及国外同类技术的详细情况,同时介绍了我国目前研究连续平压热压机的现状和迫切性。 相似文献
179.
S. M. Newman 《Agroforestry Systems》1984,2(1):49-56
Carrots, onions, radishes and peas, growing in pots were placed at various locations in a pear orchard and used as phytometers
to characterise the aerial environment. The growth of plants growing beneath the orchard canopy was not significantly less
than that of phytometers grown in the open. However, the bulb diameter of radish and onion was significantly reduced when
growing immediately beneath pear trees. Radish was selected as a suitable phytometer for further research. 相似文献
180.
A hedgerow intercropping study was conducted for 7 years in West Sumatra, Indonesia on an acid and highly Al-saturated soil to determine growth and yield responses of tree hedgerows and upland rice and cowpea intercrops. Three tree species,Paraserianthes falcataria, Calliandra calothyrsus, andGliricidia sepium and a no-tree control were planted at three lime rates with low annual fertilizer inputs of 20 kg P and 50 kg K ha–1.Paraserianthes andCalliandra grew vigorously, whileGliricidia grew poorly and was replaced after four years withFlemingia macrophylla. After four years,Paraserianthes yields declined due to tree mortality, probably due to intensive pruning.Calliandra andFlemingia were well adapted to intensive pruning (4 to 6 times per year).
Gliricidia growth was especially limited by low soil Ca availability and high soil acid saturation.Calliandra andFlemingia yields increased with liming only in the last several years of the study whileParaserianthes did not respond to lime. The species can be tentatively ranked in response to lime as:Gliricidia > Calliandra > Flemingia > Paraserianthes. 相似文献