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1.
Root growth, water potential, and yield of irrigated rice 总被引：3，自引：0，他引：3
Root length density (Lv), leaf water potential (Ψ leaf) and yield of rice were studied in 1983 and 1984 on a Phool bagh clay loam (Typic Haplaquoll) and on a Beni silty clay
loam (Aquic Hapludoll) in the Tarai region of Uttar Pradesh under naturally fluctuating shallow (0.07–0.92 m) and medium-depth
(0.13–1.26 m) water table conditions with six water regimes ranging from continuous submergence under 0.05 m ± 0.02 m (Ic)
to completely rainfed (Io). In irrigation treatments, Ic1, Ic3, Ic5, and Ic7, 0.07 m irrigation was applied on days 1, 3,
5, and 7 respectively, after the disappearance of ponded water. Maximum rooting depth (0.55 m in the shallow and 0.65 m in
the medium-depth water table) was attained at the dough stage (125 days after transplanting) and was more strongly influenced
by fluctuations in water table depth than by the water regime. For wet regimes (Ic1–Ic5), roots were concentrated at and above
the water table interface and had greater horizontal development, whereas in dry regimes, (Ic7 and Io) they were concentrated
in lower horizons and had a more vertical distribution. Like Lv, Ψ leaf was not significantly affected by water regime up to 90–95 days after rice transplanting but was significantly affected
thereafter, except for Lv beneath 0.2 m–0.25 m. Grain yields with irrigation treatments Ic1 and Ic3 under shallow and Ic1
under medium-depth water table conditions were not significantly different from those under continuous submergence, but there
was a (nonsignificant) trend to lower yield with less water. However, differences among the wet regimes (Ic, Ic1, and Ic3)
were small (141–490 kg ha–1) under shallow and 413–727 kg ha–1 under medium-depth water table conditions. The results demonstrate that optimum yield (5500–6000 kg ha–1) could be obtained under Tarai conditions by adopting an intermittent irrigation schedule of 3–5 days after the disappearance
of ponded water under shallow, and of 1–3 days under medium-depth water table conditions, in place of continuous submergence.
Received: 26 February 1996 相似文献
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M. A. A. Mamun S. Nasren K. H. Srinivasa S. S. Rathore P. B. Abhiman K. Rakesh 《Journal Of Applied Aquaculture》2020,32(1):81-93
ABSTRACTStriped catfish (Pangasianodon hypophthalmus) fingerlings were stocked (60 fishes/m3) in cemented square tanks for ornamental fishery purposes at the College Fish Farm in Mangalore. A total of 400 fishes with a mean weight (g) ranging from 3.24 ± 1.21 to 6.70 ± 1.13 and a mean length (cm) of 7.50 ± 0.94 to 9.50 ± 1.10 were examined. A severe outbreak of salt-like granule white spots was found on the body surface. Ichthyophthirius multifiliis, a ciliate pathogen, was identified as the causative agent by clinical signs, wet mount, and histopathological observations. Infected fishes were transferred and equally distributed to the 0.45 m3 glass aquaria and treated with three treatments: (T1) methylene blue + salt; (T2) raising temperature with salt; and (T3) formalin + malachite green. The best fingerling survival (55 ± 9.36%) was obtained by elevated water temperature with salt in T2. 相似文献
4.
- 1. Mahseer fishes of the genus Tor are ‘iconic species’ in Indian rivers, representing ‘flagship’ species for conservation purposes but with additional exploitable, cultural and economic values. Conservation action is required to address their vulnerability to numerous pressures on multiple habitats, and connections between them, across the extended aquatic ecosystems supporting different life stages.
- 2. Recreational angling for mahseer, along with associated wildlife and cultural tourism, is a growth industry dependent upon healthy river ecosystems.
- 3. A cyclic, ecosystem‐based model in which local people can benefit economically from sustainable mahseer exploitation through catch‐and‐release fisheries can form a basis for conservation of both mahseer and the wider river ecosystem.
- 4. Experience on the Western Ramganga River in the vicinity of the town of Bikhyasen, Uttarakhand State (in the Himalayas in northern India), demonstrates the importance of involving local people in the benefits associated with angling, wildlife and cultural tourism. This creates local incentives for river protection, and may be the most effective means for preventing destructive over‐exploitation in poor rural communities.
- 5. Recognition of this value and its recirculation to local people can form the basis for a ‘paying for ecosystems services’ (PES) market. This will benefit river ecosystems, local people, tour operators and visiting anglers, provided that local people benefit to a greater extent than through the killing of fish for non‐renewable consumption or sale.
- 6. This is the basis for a potentially transferable model which may support regional development through involving local people in markets for iconic species. Copyright © 2010 John Wiley & Sons, Ltd.
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Downy mildews cause considerable damage to maize (Zea mays L.) worldwide, particularly in the tropical Asia. We have evaluated a set of 42 tropical/sub-tropical maize inbred lines
developed in different countries in Asia (India, Thailand and Philippines), and Mexico, for analysing the genetic variability
for resistance to sorghum downy mildew [Peronosclerospora sorghi; SDM] and Rajasthan downy mildew [P. heteropogoni; RDM]. Experiments were carried out in replicated trials under artificial infection in field conditions against SDM and RDM
at Mandya in Karnataka, India, and Udaipur in Rajasthan, India, respectively, during 1999 and 2000. The study resulted in
identification of five inbred lines offering consistent and strong resistance to both SDM and RDM, while several inbred lines
revealed resistance only to RDM. It was also revealed that the SDM-resistant inbreds are invariably resistant to RDM, while
the RDM-resistant inbreds might show differential responses to the SDM. The maize inbred lines identified in this study with
broad-spectrum resistance to downy mildews could be potentially useful for basic and applied research work on downy mildews
in tropical Asia.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
The influence of tillage treatment and the time of crust formation after planting on the degree of surface crusting and seedling emergence of soybean (Glycine max L. Merr.), planted on the flat and on ridges, are described. Crusts were developed artificially at specific times after planting. Under non-crusted conditions (control), more rapid drying of the soil in the seed zone occurred in conventionally-tilled, ridge-planted (Tcr) and minimum-tilled, flat-planted (Tmf) seedbeds compared with excessively and conventionally-tilled, flat-planted (Tef and Tcf) seedbeds. The formation of surface crusts induced a reduction in moisture loss from the seed zone. On drying, large crust blocks with a smooth surface developed in Tef plots whereas, in Tmf plots, small crust blocks with a rough surface appeared. Both the rate of emergence and the ultimate emergence of soybeans were in the order Tef > Tcf > Tcr > Tmf under non-crusted conditions and, on average, in the order Tcr > Tcf > Tef > Tmf under crusted conditions. Crusts which formed within two days of sowing were more injurious because these were hard and impenetrable, and were present at the normal time of seedling emergence. Crusts induced 72 h after planting had less effect on seedling emergence because, by the time they could form, emergence was already almost completed. 相似文献
8.
The influence of zinc application on yield, Zn concentration and its uptake by paddy crop (Oryza sativa) was studied in a pot experiment in alluvial soils from Gwalior district. All the soils having less than 3.0 ppm 0.1 N HCl-extractable soil Zn showed significant yield response to application of Zn. The latter also resulted in significant increase in Zn concentration and its uptake by the crop. The plant tissue Zn was found to be significantly correlated at 1 % level with the soil Zn (r=0.82) and Bray's per cent grain yield (r=0.82). Critical level Zn in rice plant taken from top 15 cm of the plant was worked out by statistical procedure of Cate and Nelson and found to be 13.5 ppm below which response to applied Zn is expected. 相似文献
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