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Plant-to-plant direct competition for belowground resource in an overlapping depletion zone

Journal of Arid Land 2009年第1期1卷 9-15页

作者： Amit CHAKRABORTY Ecological Complexity and Modeling Laboratory Department of Botany and Plant SciencesUniversity of California Center for Conservation Biology University of California

In response to limited availability of soil resources in basal root zone, plant extends its roots into nearby resource-rich zones to fulfill essential resource demands for survival and reproduction. This root proliferation into that enriched zones occupied by other plants constitutes interplant overlapping rooting zones and thereby the overlapping depletion zones, causing reduction in resource uptake by neighboring plants. By incorporating this mechanism into the classic resource competition model, we study interplant direct competition through their rooting system in an overlapping depletion zone. The model results indicate an extension of Tilman’s R* rule that has already been proved true when plants compete indirectly through their effect on shared resources. The results reveal that plant’s direct competitive ability (i.e., the ability to occupy an overlapping depletion zone by excluding others) can be characterized by its R*-value, where a best competitor having lowest R*-value excludes others from an overlapping zone and occupies the zone by depleting the resource level to the lowest as in its non-overlapping depletion zone. By analyzing the model, we find a suite of traits that confers R* variation among directly competing plants. This suite of traits would be a useful proxy measure for R* that do not necessarily require to establish equilibrium field monoculture—a requirement for R* measurement in the field.

关键词： resource capture efficiency niche differentiation root proliferation resource depletion zone

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Using coloured roots to study root interaction and competition in intercropped legumes and non-legumes

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Journal of Plant Ecology 2010年第3期3卷 191-199页

作者： Giacomo Tosti Kristian Thorup-Kristensen Department of Agriculture and Environmental Sciences University of PerugiaBorgo XX Giugno 7406121 PerugiaItaly Department of Agriculture and Ecology Faculty of Life SciencesUniversity of CopenhagenHøjbakkegaards Alle 13DK-2630 TaastrupDenmark

Aims root interactions between neighbour plants represent a fundamental aspect of the competitive dynamics in pure stand and mixed cropping *** comprehension of such phenomena places big methodological challenges,and still needs *** objectives of this work were(i)to test if a species with coloured roots can be used to examine the interaction in a legume-non-legume intercropping system;(ii)to verify the importance of initial root growth on the successive root development ofmixture component plants;(iii)to test if the root interaction in the shallowlayers has consequences for deep root growth and(iv)to compare the effect of intraspecific and interspecific competition on root development and biomass *** A detailed study on root growth and interaction was carried out using rhizotron tubes where two legume species were grown in pure stands or were intercropped with red beet,a variety of Beta vulgaris *** clear red *** the rhizotrons,the three species were grown either without competitors,with two plants of the same species to measure intraspecific competition or with one legume and one red beet plant to study interspecific *** use of mixtures where one component has clearly coloured roots,together with several scalar measurements of root depth and proliferation,allowed the measurement of the root system of each species when grown in the *** findings The use of rhizotron tubes coupled with species with coloured roots represented a valuable method to study the belowground interaction in mixed cropping *** initial root growth was a very important feature for the subsequent dominance of a species and it was not related to seed *** root growth was also important because the root interactions in the shallower soil layers were found to influence the root growth in deeper *** root system of the red beet showed much faster and deeper growth than that of the legumes,and made red beet

关键词： red beet root competition root interaction root proliferation rhizotron

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Productive Performance and Response of Green Chilli （Capsicum annum L.） to Drip Irrigation Schedules under Water Limited Conditions

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Journal of Agricultural Science and Technology 2010年第2期4卷 48-55页

作者： B.K. Ramachandrappa H.V. Nanjappa T.M. Soumya B.N. Prabhakara Department of Agronomy Agriculture College University of Agricultural Sciences GKVK Bangalore Karnataka 560065 India

Drip irrigation is often preferred under water limited conditions over the other irrigation methods because of its high water application efficiency on account of reduced surface evaporation and percolation losses. The major limitation of drip irrigation is its initial investment. Therefore, there is a need to reduce the cost of drip installation by altering the planting geometry besides enhancing the productivity and moisture use. Results of the two years field study conducted on sandy loam soils revealed that drip irrigation at 1.0 Epan with normal row system （60 cm×30 cm） registered significantly higher yield of green chilli（ 14.08 t ha^-1） which was on par with 0.8 Epan two rows paired system （90-45-90 cm×30 cm：13.45 t ha^-1） and significantly lowest was noticed with 0.6 Epan four rows paired system（45-45-45-120 cm×30 cm ）（5.50 t ha^-1）. The quality parameters viz; TSS and Ascorbic acid were significantly higher with drip irrigation at 1.0 Epan with normal row system and lowest was observed with 0.6 Epan four rows paired system. Total water used was maximum in 1.0 Epan （691.7 mm） followed by 0.8 Epan irrigation （590.2 mm） and the lowest was recorded in 0.6 Epan irrigation （488.8 mm）. There was a saving of water by 14.68 percent and 29.34 percent under 0.8 and 0.6 Epan drip irrigation schedules respectively over 1.0 Epan. Indications of less leaf water potential in 1.0 Epan drip irrigation （-0.58 to-0.67 MPa） followed by 0.8 Epan （-0.61 to-0.68 MPa） and more negative leaf water potential in 0.6 Epan （-0.71 to-0.88 MPa） in relation to water applied were observed. Water use efficiency recorded was maximum in 0.6 Epan normal row systems （24.1 Kg ha-mm^-1） and the least was recorded in 0.6 Epan four rows paired system （11.3 Kg ha-mm^-1）. The significantly higher root growth characters such as root length （42.6 cm）, number of primary roots （28.7）, root dry weight （11.05 g plant^-1） and maximum depth of penetration were recorded with 0.6 Epan four rows paired system a

关键词： Drip irrigation greenchilli planting method water requirement leaf water potential root proliferation

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