首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 0 毫秒
1.
Leaf extracts and mulch from 14 multipurpose trees were used to test their effects on maize germination, growth and yield. Maize germination was significantly reduced by leaf extracts of all species with increasing extract concentration. The most drastic reductions were caused by Gliricidia sepium , Tetrapleura tetraptera , Lonchocarpus sireceus , Senna siamea and Leucaena leucocephala . Terminalia superba , Tetrapleura tetraptera , Pithecelobium dulce , Gliricidia sepium and Senna siamea significantly reduced maize root growth at the lowest extract concentration, while shoot length was most significantly reduced by Gliricidia sepium , Leucaena leucocephala , Alchornea coordifolia , Pithecelobium dulce , Terminalia superba , and Tetrapleura tetraptera at all concentrations. Growth of maize in pots and yield in the field were controlled by nitrogen supply and uptake. Fast-decomposing leaf material rich in nitrogen promoted growth and yield of maize. Thus Leucaena leucocephala and Gliricidia sepium , both nitrogen-fixing legumes with high nitrogen contents and fast-decomposing leaf materials, significantly increased maize growth and yield. This suggests that the negative effects of leaf extracts observed in the laboratory are ecologically irrelevant in the field.  相似文献   

2.
Reduction of crop yields due to resource competition from tree hedges is a serious drawback of hedgerow intercropping. This work quantified the competition of six potential hedgerow tree species ( Calliandra calothyrus , Desmodium ransonii , Flemingia congesta , Gliricidia sepium , Cassia spectabilis and Tithonia diversifolia ) on mung bean ( Vigna radiata ) grown as hedgerow intercrops at Pallekelle in the mid-elevational (367 m above sea level), subhumid (rainfall of 1400 mm year−1) zone of Sri Lanka. Leaf area, total biomass and yield of mung bean in hedgerow intercrops showed a clear reduction closer to the hedgerows, whereas no such reduction was observed in a sole crop of mung bean. At 30 cm from the hedgerow, growth and yield of mung bean were significantly lower than in the sole crop, indicating significant competition from hedgerows. However, growth and yield of mung bean increased with increasing distance from hedgerows so that, at 150 cm, mung bean under Gliricidia and Desmodium showed significantly greater growth and yields than the control. In contrast, even the maximum mung bean yields under the rest of the species did not reach that of the control. The differences in competition with different hedgerow species are discussed in terms of variations between tree species in biomass production, quality of prunings and the possibility of root competition.  相似文献   

3.
Six-week-old wheat seedlings ( Triticum aestivum ) grown in pots with an alfisol soil with vertic properties and mulched at a rate equivalent to 10 t ha−1 with leaf prunings of Grevillea robusta, Erythrina abyssinica, Gliricidia sepium, Albizia schimperiana. Acacia nilotica. Acacia polyacantha, Leucaena leucocephala, Leucaena pallida and Entada abyssinica were used to diagnose nutrient contributions by these tree species. A control treatment of 20kg P + 30kg N ha−1 was chosen as the reference treatment for the vector analysis applied to the mulch effects. Nitrogen was found to be the most important nutrient in seedlings mulched with L. pallida, L. leucocephala, Erythrina abyssinica and to a lesser extent A. schimperiana. Other nutrients of these mulches were also in the deficiency zone but with shorter vectors and therefore with lower impact. Since all these mulches showed increased values for shoot dry weight, nutrient concentration and nutrient uptake they have still reserves for further plant growth and appear therefore to be good mulch sources for annual crops. In contrast, wheat seedlings treated with A. polyacantha and Entada abyssinica had at least some vectors in the toxic zone due to an excess of nutrients while Grevillea treated plants showed a typical toxicity response with large vectors for all nutrients in between the toxic and the antagonistic zone. Allelopathic compounds might also have been involved.  相似文献   

4.
Leaves of nine agroforestry tree species (Grevillea robusta, Erythrina abyssinica, Gliricidia sepium, Albizia schimperiana. Acacia nilotica. Acacia polyacantha, Leu-caena leucocephala, Leucaena pallida and Entada abys-sinica) were compared in a glasshouse incubation experiment under natural temperature conditions to relate the observed nitrogen mineralization pattern to quality factors of the mulch material such as N, lignin, phenolic and tannin content and C/N ratio, lignin/N ratio, phenolic/N ratio and (lignin -I- phenolics)/N ratio. Separation of the plant material into leaflets and petioles/rachis or into leaves and petioles with subsequent chemical analyses revealed large differences in the quality of the material not only between species but also amongst plant parts within the same species. Erythrina abyssinica, G. sepium, L. leucocephala and L. pallida had a rapid nitrogen release especially during the early sampling dates and were superior compared with mulch treatments of G. robusta, A. polyacantha, and Entada abyssinica. Immobilization processes started around 5 weeks after incubation and continued up to the end of the experiment, 9 weeks after incubation. N and lignin content, C/N ratio, lignin/N ratio, phenolics/N ratio and (phenolics + lignin)/N ratio were all significantly correlated with mineralized nitrogen after 3 weeks but their influence in driving the mineralization pattern decreased with incubation time.  相似文献   

5.
Cotton ( Gossypium hirsutum L.) is one of the most profitable cash crops in Greece. It is usually grown as a monoculture but it is also found in rotation systems with other plant species including sugar beet ( Beta vulgaris L.). Poor cotton performance following sugar beet was persistently reported by farmers. Glasshouse and field experiments were conducted to determine whether: 1) sugar beet as a preceding crop affected seed germination, seedling growth and yield of cotton; and 2) N fertilization can minimize the effects of sugar beet. Seedling growth was diminished by sugar beet extracts; emergence, seed-cotton, stalks and biomass of cotton in pots were affected by the soil incorporation of sugar beet residues; and emergence, flowers, bolls and seed-cotton production in the field were also affected by the soil incorporation of sugar beet residues. These harmful effects were eliminated by N fertilization.  相似文献   

6.
The present study was conducted to investigate the allelopathic effects of Parthenium hysterophorus weed on seed germination and seedling growth of tef. Flower, stem, root and leaf aqueous extracts of Parthenium at 0, 1, 5, and 10 % concentrations were applied to determine their effect on tef seed germination and seedling growth under laboratory conditions. Increasing concentrations of aqueous extracts of Parthenium from leaf and flower inhibited seed germination and complete failure of seed germination was recorded when the extract concentration from the leaf part was 10 %. In contrast, aqueous extracts from stem and root had no effect on tef seed germination. Roots appeared more sensitive to allelopathic effect than shoots. Extracts from flower, root and stem had a stimulatory effect on shoot length at all concentration levels, as against an inhibitory effect of leaf extracts. Root extracts at low concentration (1 %) greatly promoted root length but aqueous extracts from leaf and flower inhibited root length.  相似文献   

7.
Black mustard [Brassica nigra (L.) Koch.] contains water‐soluble allelochemicals that inhibit the germination and growth of other species. This characteristic could be used in weed management programmes. Greenhouse and laboratory experiments were conducted to determine the effects on wild barley (Hordeum spontaneum Koch.) germination and seedling growth of (i) preceding crops, (ii) fresh black mustard residue incorporation, and (iii) black mustard leaf, stem, flower and root water extract concentrations. Growth of wild barley, as indicated by plant height and weight, was significantly reduced when grown in soil previously cropped to black mustard compared with that cropped to wild barley. Soil incorporation of fresh black mustard roots and both roots and shoots reduced wild barley germination, plant height and weight when compared with a no‐residue control. In bioassays, black mustard extracts reduced wild barley hypocotyl length, hypocotyl weight, radicle weight, seed germination, and radicle length by as much as 44, 55, 57, 63 and 75 %, respectively, when compared with a water control. Increasing the water extract concentrations from 4 to 20 g per 100 ml of water of all black mustard parts significantly increased the inhibition of wild barley germination, seedling length and weight. Based on 8‐day‐old wild barley radicle length, averaged across all extract concentrations, the degree of toxicity of different black mustard plant parts can be ranked in the following order of inhibition: leaves > flowers > mixture of all plant parts > stems > roots.  相似文献   

8.
This article presents various experiments conducted under semi-controlled conditions to determine the effects of temperature on germination, phenology, growth and freezing in Chenopodium quinoa, a pseudocereal originating from the cold and dry Andean altiplano. Traditional landraces and recently released cultivars from distinct geographical origins were compared in order to look for local adaptation or breeding improvement with respect to low temperatures. Germination was evaluated in 10 cultivars at temperatures between 2 and 20 °C. Plant growth and development were examined in three cultivars over the growing cycle, under minimum temperature between 8 and 13 °C and maximum temperature between 20 and 28 °C. The thermal time concept was used to compare the various treatments and estimate the phyllochron, as well as the base temperature and optimum temperature for leaf appearance, time to flowering and leaf width growth. Two cultivars at the vegetative stage were compared for night freezing tolerance down to −6 °C, registering leaf exotherms and plant survival rate. The influence of plant water status and the possible protective or detrimental role of leaf epidermal vesicles were also examined. Low temperatures down to 2 °C delayed germination without impeding it totally. Base temperature for germination varied between −1.9 and +0.2 °C, with negative values in 9 cultivars out of 10. Thermal sensitivity in germination was not related to the geographic origin of the cultivars. Leaf appearance and time to flowering showed similar base temperatures near 1 °C. Phyllochron varied from 12.9 to 17.2 °C d with lower values in the two recently released varieties than in the traditional landrace. Leaf width increased from a base temperature around 6 °C up to an optimum temperature between 20 and 22.5 °C. Freezing experiments showed that no plant could survive after 4 h at −6 °C, while no serious effect was noted down to −3 °C. Leaf exotherms confirmed that ice nucleation occurred between −5 and −6 °C in most of the plants, the traditional landrace showing a lower freezing tolerance than the selected line. Low leaf water status delayed the freezing process, while leaf vesicles did not seem to play any protective or detrimental role towards leaf freezing. Implications of these results for quinoa crop adaptation to the Andean environment are discussed.  相似文献   

9.
Major limitations of bean ( Phaseolus vulgaris L.) production in arid and semiarid regions are lack of moisture and low soil fertility. An experiment was conducted to determine the effects of soil moisture and N : P : K (20 : 10 : 10) fertilizer on root and shoot growth of two cultivars of bean: cv. Carioca, an indeterminate Brazilian landrace, and cv. Prince, a determinate cultivar grown in Europe. Carioca appears generally stress-tolerant while Prince is intolerant. Seedlings were grown in pots of non-sterile soil at 30, 60 or 90 % field capacity (FC), and given 0, 0.1 or 1 g (kg soil)–1 of compound fertilizer. The soil contained a population of effective Rhizobium . Growth of both cultivars was greatest in the high moisture and high nutrient treatments. Root fractions were highest at low nutrient supply; the effect of water was not significant. Leaf fraction decreased as root fraction increased. Numbers of nodules were highest at high and intermediate moisture when no fertilizer was applied. Numbers were lowest at 30 % FC and at the highest fertilizer rate. Masses of nodules and fractions followed the same pattern. Decreasing water regime reduced the relative growth rate (RGR) of Prince, while Carioca maintained high RGR at unfavourable conditions of water and nutrients. Net assimilation rates (NAR) were unaffected by nutrient addition, and reduced by low moisture regime. Water use efficiencies (WUEs) were reduced by water stress but increased by nutrient deficiency. The water utilization for dry matter production was optimal at 60 % FC.  相似文献   

10.
PBAT与PPC是化学合成型全生物可降解材料，也是目前地膜可降解材料的研究热点，本研究重点探讨PBAT和PPC材料可降解地膜的实际使用效果。设置PBAT-PPC地膜、PBAT-PPC-BioM地膜、传统PE地膜和露地对照NoFilm处理。通过田间试验，探讨不同地膜处理对地表温度、杂草和豇豆产量的影响，并评估地膜降解性能和最终经济效益。结果表明：PBAT-PPC地膜可有效提高5—7月份地表温度0.9ºC，降低7—8月份地表温度0.2~1.6ºC。PBAT-PPC地膜与PBAT-PPC-BioM地膜均能显著提高了豇豆产量，分别较不覆膜对照处理产量提高37%和22%。PBAT-PPC地膜与PE地膜的杂草产量无显著差异，较露地杂草降低45%。试验期内，可降解地膜降解等级达到4~5，满足后期翻耕回田要求。效益分析表明，尽管可降解地膜成本较高，但增产效果显著，整体收益高于无地膜对照，且无环境风险。综上所述，基于PBAT和PPC的可降解地膜性能优异，在豇豆生产中增效明显，具有较高的推广价值。  相似文献   

11.
Seeds of Paceño and Cuarenteño cultivars of cowpea (Vigna unguiculata L. Walp.) were tested for salt and drought tolerance at germination, seedling emergence and early seedling growth in NaCl and PEG‐8000 solutions of different osmotic potentials (0, ?0.2, ?0.4, ?0.6, and ?0.8 MPa). Daily and final germination and emergence percentage, as well as germination and seedling emergence rate, and seedling growth were recorded under controlled conditions. Results showed that germination and emergence rate were delayed by both solutions in both cultivars, with differences between cultivars among growth stages, given that cultivar Cuarenteño, showed a higher germination rate than Paceño in NaCl, but Paceño was less affected by NaCl and PEG solutions at the emergence stage. Sodium chloride had a lesser effect on both cultivars in terms of germination rate, emergence rate and the final germination and emergence percentage than did PEG‐8000. This conclusively proves that the adverse effect of PEG‐8000 on germination, emergence and early seedling growth was due to the osmotic effect rather than the specific ion. Seedling growth was reduced by both stresses, but NaCl usually caused less damage than PEG to cowpea seedlings, suggesting that NaCl and PEG acted through different mechanisms.  相似文献   

12.
24-Epibrassinolide belongs to the brassinosteroid family of plant hormones, and carbenoxolone is a synthetic analogue of glycyrrhizic acid that inhibits enzymes important in steroid and prostaglandin action in animals. The effect of these compounds on root nodulation, root growth and shoot growth of Glycine max (L.) Merr. cv. Tracy M was examined. Epibrassinolide reduced total nodulation, plant wet weight, root length, shoot length, first internode length and number of lateral roots. Effects were observed at concentrations as low as 0.1 μ M . Carbenoxolone reduced lateral root formation, but did not reduce nodule numbers, root length or weight, nor stem length or weight.  相似文献   

13.
几种水土保持先峰牧草叶浸提液化感作用效应的研究   总被引：1，自引：0，他引：1  
李发林 《中国农学通报》2010,26(18):401-405
采用生物检测方法,以萝卜为受体植物,探讨了先峰牧草宽叶雀稗、百喜草、平托花生、圆叶决明4种牧草叶浸提液对萝卜种子发芽和幼苗生长的化感效应。牧草水提液对萝卜发芽率在高浓度百喜草、平托花生处理时受体罗卜萌发受到极显著抑制,平托花生与宽叶雀稗、圆叶决明处理所产生的抑制作用的差异达极显著水平。牧草叶浸提液对罗卜根长有显著的影响;7.5％、10.0％浓度时,对受体萝卜单株根干重影响表现为平托花生都表现出为促进作用,而其它3种牧草处理则都表现为抑制作用,且与百喜草处理间有显著差异;10.0％浓度下,4种牧草叶浸提液处理都促进幼苗生长,且圆叶决明、百喜草处理比对照有极显著差异;牧草叶浸提液对幼苗和植株干重影响都不显著。  相似文献   

14.
Annual crops grown in association with contour hedgerows often show yield reductions. This paper quantifies the variation of above- and below-ground environmental factors in hedgerow intercrops involving six different tree species ( Calliandra calothyrus , Desmodium ransonii , Flemingia c ongesta , Gliricidia sepium , Cassia spectabilis and Tithonia diversifolia ) and thereby shows the effects of tree hedges on mung bean ( Vigna radiata ). Compared to a sole crop of mung bean, most hedgerow intercrops removed greater soil nitrogen, whereas all removed lower soil phosphorus. Mung bean closer to the hedgerows had lower N and P, indicating competitive capture of nutrients by hedges. Most hedgerow intercrops had greater top-soil water because of their shading effect, especially near hedgerows. However, greater absorption by tree root systems decreased subsoil water near hedgerows late in the season. Soil temperature was lower in most hedgerow intercrops than in the control and increased with increasing distance from hedges. During initial stages of mung bean growth, radiation interception of intercrops was greater than that of the control, especially closer to hedgerows. However, after the first month, radiation interception of the sole crop was either equal to or greater than that of hedgerow intercrops. There was significant variation between tree species in all these environmental factors. Gliricidia , which allowed greater mung bean yields, also allowed greater nutrient capture by mung bean, greater top-soil water availability, lower extraction of subsoil water and lower soil temperatures.  相似文献   

15.
Cowpea plants ( Vigna sinensis Savi.) were grown in pots for two successive years. These plants were daily maintained water holding capacities (15, 25, 45, 65 %).
The foliage of plants grown at every level of soil moisture was sprayed till dripping with kinetin solutions (0, 10, 20, 40 mg/1) three times after, 3, 6 and 9 weeks from sowing. Samples were taken at the two physiological stages before flowering and during flowering for growth measurements and determination of nitrogen fractions.
Water shortage led to retardation of stem length, number of internodes, number of leaves and dry weight of shoots. Kinetin reduced stem length of cowpea shoots. On the other hand, it exhibited stimulative effect when applied at concentrations 10 and 20 mg/1 on number of internodes, and dry weight of shoots.
Water stress decreased total–N and protein–N contents of cowpea shoots. On the other hand total soluble–N content was increased under the same conditions. Kinetin increased total–N and protein–N contents of cowpea shoots. Meanwhile, the same growth regulator decreased total soluble–N when applied at 45 %, 25 % and 15 % W.H.C. levels.  相似文献   

16.
Cowpea ( Vigna unguiculata L. Walp) is an important food legume grown under rainfed conditions in the tropics. However, the yield of this crop varies widely in most tropical ecosystems due to crop and environmental factors. Experiments were carried out to evaluate the effects of seed characteristics, soil moisture at planting and the season of crop establishment on growth and yield parameters of cowpea as these influence the productivity of the crop. Growth and yield of cowpea plants grown from small seeds with a high conductivity of their lea-chates were significantly lower than those grown from large seeds. Root growth of seedlings was most prominent under moderate soil moisture levels. Low soil moisture retarded root growth by reducing dry weights and suppressing the development of laterals. Shoot growth was more sensitive to increasing soil moisture stress than root growth. Planting cowpea in the wet season produced the highest yields. Within a season, growth and yield were higher when the crop was planted early. Establishment of the crop later in the season produced better quality seeds measured in terms of germination after controlled deterioration.  相似文献   

17.
Field experiments were conducted to determine the effects of tillage (ploughing followed by one rotary hoeing (CT), rotary hoeing (MT) and no-tillage (NT)) and type of fertilization (NP 154/75 kg ha−1, digested farmyard manure 30 t ha−1) on growth (biomass and roots), N-accumulation and nodulation of vetch plants (Vicia sativa cv. Alexander) at different stages. The highest dry matter yields and root weight were determined for the NT and the lowest for the CT systems. The NT system promoted nodulation of vetch plants to a higher degree than the MT and CT systems. At the time just before harvesting, the N-accumulation in the above ground plants, was 54.3 for CT, 76.7 for MT, and 109.0 kg ha−1 for NT, and the corresponding values at roots were 73.3, 112.0 and 173.3 kg ha−1. Growth and nodulation of vetch plants was in general much better on farmyard manure plots than it was with the NP fertilization. The closest correlation coefficients between dry matter of biomass and roots on the one hand, and number of nodules and percentage N in roots on the other, were found with NT. The highest correlation between nodulation and percentage N in roots (r = 0.91***) was observed at the 128-days-old vetch plants. The highest correlation between the number of nodules and percentage N in biomass (r = 0.82**) was found at the beginning of the plants' flowering period. *, **, *** indicate significance at P = 0.05, 0.01 and 0.001 respectively.  相似文献   

18.
Abstract The objective was to study soil water conservation and physiological growth of wheat (Triticum aestivum L.) using composted cattle manure applied either as mulch or incorporated with soil at 20 Mg ha?1. Haruhikari, a relatively drought‐sensitive and Hongmangmai, a relatively drought‐tolerant wheat, were the cultivars studied under both adequate and deficit irrigation. Fourteen weeks after sowing (WAS), the number of tillers and leaves was significantly reduced by 19 % and 30 % respectively under deficit irrigation and Hongmangmai produced slightly (10 %) more tillers than Haruhikari. Unlike mulching, the incorporation of manure had favourable effects on plants in terms of shoot dry mass (SDM) by 36 % and number of tillers and leaves by 40 %. Haruhikari produced substantially (29 %) greater root mass under adequate irrigation but Hongmangmai produced slightly (2.7 %) more roots and responded much better to manure use whether under adequate or deficit irrigation. As a result, Hongmangmai suffered less severe reductions in tillers and biomass under water stress. In comparison, the mulched manure treatment saved 15 % and 64 % respectively more water than the control and the treatment incorporating manure, but this advantage in water‐saving did not translate to superior plant growth. Leaf water potential (ψl) under adequate irrigation significantly exceeded that under deficit irrigation by 27 % and the ψl of Haruhikari exceeded that of Hongmangmai by 15 %. However, Hongmangmai may be considered more tolerant of dehydration since it maintained much higher net photosynthetic rates (PN) even with a lower leaf water potential. The reduction in the PN and intracellular carbon dioxide concentration (Ci) of the cultivars under deficit irrigation was on account of decreasing stomatal conductance (gs) and transpiration rate but on average, the gs of Hongmangmai significantly exceeded that of Haruhikari by as much as 0.53 under adequate irrigation and 0.22 under deficit irrigation. In conclusion, we suggest that the drought tolerance of Hongmangmai was related to its superior root growth and greater ability than Haruhikari, to efficiently utilize incorporated manure for growth under water stress.  相似文献   

19.
The effects of alternating day/night temperatures, varying in maxima and minima but all averaging 30 °C, on germination and seedling characteristics of Sorghum bicolor L. (Moench) were investigated. Seeds of sorghum CSV 15 were soaked in 2, 4 or 6 g NaCl l−1 solutions for 2 days at 25 °C, soaked in water for 1 day at 25 °C, or untreated. After treatment, drying and storage, seeds were germinated at 30/30 (day/night), 35/25, 40/20 or 41/19 °C temperature regimes under a polyethylene glycol-induced drought level of −3 bar. Results revealed no advancement of germination percentage but a partial increase in germination speed by osmotic seed treatments. All three osmotic treatments also reduced the plumule/radicle ratio owing to a speculated increase in root over shoot growth. Temperature regimes significantly influenced both germination and seedling characteristics with the optimum temperature appearing to be 35/25 °C. Increasing the temperature amplitude from 30/30 to 35/25 °C increased germination speed, which was reduced by incremental increases in temperature amplitude to 40/20 or 41/19 °C.  相似文献   

20.
Leaf leachate of Anthemis cotula inhibits seed germination of the commonly cultivated field crops in Kashmir valley. Among the four indices of germination (GT, S, AS, CRG), S (speed of germination) and AS (speed of accumulated germination) are sensitive enough to establish the allelopathic activity of the leaf leachate. Inhibition of seed/grain germination of the field crops showed a species‐specific and dose‐dependent response with highest inhibition occurring at 5000 ppm concentration. Brassica campestris seeds are most sensitive, whereas those of Vigna radiata are least sensitive. Interestingly, achene germination of A. cotula is promoted by its own leachate at low concentrations and inhibited at high concentrations.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号