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R. Dinesh 《植物养料与土壤学杂志》2004,167(2):189-195
In this study, leguminous crops like Atylosia scarabaeoides, Centrosema pubescens, Calopogonium mucunoides, and Pueraria phaseoloides. grown as soil cover individually in the interspaces of a 19‐yr‐old coconut plantation in S. Andaman (India) were assessed for their influence on various microbial indices (microbial biomass C, biomass N, basal respiration, ergosterol, levels of ATP, AMP, ADP) in soils (0–50 cm) collected from these plots after 10 years. The effects of these cover crops on . CO2 (metabolic quotient), adenylate energy charge (AEC), and the ratios of various soil microbial properties viz., biomass C : soil organic C, biomass C : N, biomass N : total N, ergosterol : biomass C, and ATP : biomass C were also examined. Cover cropping markedly enhanced the levels of organic matter and microbial activity in soils after the 10‐yr‐period. Microbial biomass C and N, basal respiration, . CO2, ergosterol and levels of ATP, AMP, ADP in the cover‐cropped plots significantly exceeded the corresponding values in the control plot. While the biomass C : N ratio tended to decrease, the ratios of biomass N : total N, ergosterol : biomass C, and ATP : biomass C increased significantly due to cover cropping. Greater ergosterol : biomass C ratio in the cover‐cropped plots indicated a decomposition pathway dominated by fungi, and high . CO2 levels in these plots indicated a decrease in substrate use efficiency probably due to the dominance of fungi. The AEC levels ranged from 0.80 to 0.83 in the cover‐cropped plots, thereby reflecting greater microbial proliferation and activity. The ratios of various microbial and chemical properties could be assigned to three different factors by principal components analysis. The first factor (PC1) with strong loadings of ATP : biomass C ratio, AEC, and . CO2 reflected the specific metabolic activity of soil microbes. The ratios of ergosterol : biomass C, soil organic C : total N, and biomass N : total N formed the second factor (PC2) indicating a decomposition pathway dominated by fungi. The biomass C : N and biomass C : soil organic C ratios formed the third principal component (PC3), reflecting soil organic matter availability in relation to nutrient availability. Overall, the study suggested that Pueraria phaseoloides. or Atylosia scarabaeoides were better suited as cover crops for the humid tropics due to their positive contribution to soil organic C, N, and microbial activity. 相似文献
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G. V. Subbarao C. Johansen M. K. Jana J. V. D. K. Kumar Rao 《Biology and Fertility of Soils》1990,10(1):11-16
Summary Once symbiosis between the pigeonpea cultivar ICPL 227 and the Rhizobium sp. strain IC 3024 is established, it is efficient in fixing N2 under saline conditions and can support growth comparable to N-fed plants in growth media with up to 6 dS m-1 salinity. However, the early stages of establishment of the pigeonpea-IC 3024 symbiotic system have proved sensitive to salinity. The present study showed that the number of nodules was markedly reduced at 8 dS m-1 salinity; however, nodule development and functioning were not affected by salinity in the pigeonpea-IC 3024 symbiosis. The symbiotic system of Atylosia platycarpa and Rhizobium sp. strain IC 3087 was established successfully even at 12 dS m-1 and supported growth comparable to that of N-fed plants. P levels in leaves were increased under saline conditions in N-fed and N2-fixing pigeonpea and A. platycarpa. There were no consistent differences in the leaf Na and chloride levels between N-fed and N2-fixing plants of pigeonpea and A. platycarpa. The present study suggests that the rhizobial symbiosis may not be a necessary factor for initial screening of pigeonpea and related wild species for salinity tolerance.Submitted as JA No. 964 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) 相似文献
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K. B. Saxena L. Singh M. V. Reddy U. Singh S. S. Lateef S. B. Sharma P. Remanandan 《Euphytica》1990,49(3):185-191
Summary
Atylosia scarabaeoides (L.) Benth., a wild relative of pigeonpea, possesses several useful genes which can be utilized for pigeonpea improvement. In the present study, 33 accessions of A. scarabaeoides were evaluated at ICRISAT Center during the 1987 rainy season for variation in some useful traits to identify parents for inter-generic hybridization. A large variation was observed for leaf components, seed size, pod length, seeds/pod, days to flowering, seed protein, sulphur amino acids, resistance to cyst nematode, phytophthora blight, sterility mosaic, fusarium wilt, pod borer, pod fly, and pod wasp. Only four accessions were found to have more than 28% protein content. Methionine and cystine contents were marginally higher than in pigeonpea but the variation was not large enough to utilize them in the breeding program. In A. scarabaeoides. accessions resistant to fusarium wilt, phytophthora blight, sterility mosaic, and cyst nematode were detected. Compared to pigeonpea, the A. scarabaeoides accessions were less susceptible to lepidopteran borer and were immune to pod fly damage. Accessions ICPW 89 and ICPW 111 in short- (100–120 days), and ICPW 94 and ICPW 118 in medium-duration (140–180 days) were identified as potential parents for use in inter-generic hybridization.ICRISAT Journal Article No. 967 相似文献
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Summary
Atylosia scarabaeoides
Benth. and A. platycarpa
Benth., close relatives of the species Cajanus cajan (L.) Millsp., were screened for photoperiodic response. Four photoperiods ranging from 12 h 45 min to 19 h were studied in three environments. A. scarabaeoides flowered freely only in the first photoperiod. A. platycarpa not only flowered early (39 to 63 days after planting) in all four photoperiods, but also exhibited a relatively constant vegetative phase up to 16 h of illumination.
Cajanus cajan, in which most cultivars-if not all-exhibit a response to photoperiod, was successfully hybridized with the two Atylosia species. It is suggested that genes for earliness and insensitivity to day-length could be transferred from A. platycarpa to C. cajan. 相似文献
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