Biomass Allocation

Various aspects of the water economy were investigated for a range of herbaceous species varying in relative growth rate. Plants were grown in a growth chamber with a non-limiting supply of water and nutrients, and the rate of transpiration, short-term intercellular CO2 concentration and long- term carbon isotope discrimination (∆) in the leaves were determined. No correlation was found between the relative growth rate of these species, and the transpiration rate per unit leaf area, the intercellular CO2 concentration and the 13 C-discrimination. There was a positive correlation, however, with the rate of water uptake per unit root weight. From these observations we infer that the previously observed differences in photosynthetic nitrogen-use efficiency, the rate of photosynthesis per unit leaf nitrogen, can not be explained by variation in intercellular CO2 concentration. These data were also used to analyse correlations between ∆ and both growth parameters and chemical composition...

... In the late winter, when the stresses of frost, drought and photo-inhibition interact and the stability of the hardiness stage is violated by large temperature amplitudes and fast changes, LP exhibits more visual damage ( Karlman, 1986). ...

Forest managers now operate in an information-rich but increasingly challenging environment in which the competing demands of environmental stewardship and sustainable management must counter-balance the demands of increased production and profitability. Management support tools, in particular, decision support systems are essential aids in this operating environment. A dynamic forest growth model, CArbon BALAnce (CABALA), that links carbon, water and nitrogen flows through the atmosphere, trees and soil including soil organic matter is presented here as a central part of a silvicultural decision support system.The strong linkage between stand biomass allocation and external environmental conditions make CABALA a model suitable for exploring stand management options and the effects of factors such as frost and drought on growth.The model performance is verified extensively using fertiliser, spacing and thinning trials. Predictions of nitrogen mineralisation, light interception, plant water stress, and biomass allocation as well as stand growth and stand leaf area index are tested with observed data.

Commercial potting media often contain substantial amounts of peat that was mined from endangered bog and fen ecosystems. The main objectives of this study were to assess (1) whether the amendment of 0, 20, 40, 60, 80 and 100%(v/v) of vermicompost (VC) to a ...

Commercial potting media often contain substantial amounts of peat that was mined from endangered bog and fen ecosystems. The main objectives of this study were to assess (1) whether the substitution of peat by vermicompost (VC) in potting substrate affects the emergence and biomass allocation of tomato seedlings (Lycopersicon esculentum Mill.) under greenhouse conditions and (2) whether VC amendments in seedling substrate affect tomato yields and fruit quality after plants were transplanted into equally fertilized field soil. Amended VC was produced of food and cotton waste in a windrow system by Eisenia fetida Sav. Vermicompost amendments significantly influenced, specifically for each tomato variety, emergence and biomass allocation (root:shoot ratio) of seedlings. Marketable yields of field tomatoes remained unaffected by VC amendments in seedling substrates. Peel firmness and glucose-fructose ratios of fruits were variety-specifically affected by VC amendments in seedling substrates. Results show that vermicompost could be an environmentally friendly substitute for peat in potting media with no detrimental effects on seedling performance and fruit quality.

This study investigates the effects of slope aspect on plant community characteristics such as plant cover, species composition and above-ground biomass production in Mediterranean trees and shrubs in two climatological regions. Two experimental sites were selected in a climatic gradient that runs from the foothills of the Judean Hills to the northern Negev desert in Israel. In each site, 16

The effect of ‘partial root drying’ (PRD) compared with other irrigation strategies, viz. full irrigation (FI) and deficit irrigation (DI), on morphological and physiological characteristics of potato (Solanum tuberosum L. cv. Folva) were investigated at tuber initiation stage. Potatoes were grown in pots with roots split equally between two soil columns. In FI, the whole root system was irrigated at 100% of evapotranspiration (ETfull); in DI 50% of ETfull was irrigated to the whole root system; in PRD 50% of ETfull was irrigated to one soil column while the other was allowed to dry, and irrigation was shifted when 80–85% of plant available water in the dry side had been used. Midday leaf water potential was similar for all treatments at 9 days after onset of treatments (DAT), while it was significantly lower in PRD than in FI and DI plants at 21 DAT. Photosynthesis, stomatal conductance, and transpiration were generally greater in FI plants. Compared to FI, both DI and PRD significantly decreased leaf area and biomass. DI decreased biomass allocation to leaves and stems while increasing it into roots and tubers. PRD increased biomass allocation to roots. ET under PRD was ca. 80% of DI and FI until six DAT, thereafter ET of DI and PRD was similar and was significantly less than that of FI. Water use of DI and PRD plants was 37% less than that of FI. Water use efficiency (WUE) and transpiration efficiency were similar for PRD and FI plants, and were significantly less than those of DI plants. Conclusively, given the same amount (50% of ETfull) of irrigation, PRD has no advantages compared to DI in terms of biomass production and WUE in potato at tuber initiation stage.

We examined the capacity of the galling aphid, Pemphigus betae, to manipulate the sink-source translocation patterns of its host, narrowleaf cottonwood (Populus angustifolia). A series of 14C-labeling experiments and a biomass allocation experiment showed that P. betae galls functioned as physiologic sinks, drawing in resources from surrounding plant sources. Early gall development was dependent on aphid sinks increasing allocation from storage reserves of the stem, and later development of the progeny within the gall was dependent on resources from the galled leaf blade and from neighboring leaves. Regardless of gall position within a leaf, aphids intercepted 14C exported from the galled leaf (a non-mobilized source). However, only aphid galls at the most basal site of the leaf were strong sinks for 14C fixed in neighboring leaves (a mobilized source). Drawing resources from neighboring leaves represents active herbivore manipulation of normal host transport patterns. Neighboring leaves supplied 29% of the 14C accumulating in aphids in basal galls, while only supplying 7% to aphids in distal galls. This additional resource available to aphids in basal galls can account for the 65% increase in progeny produced in basal galls compared to galls located more distally on the leaf and limited to the galled leaf as a food resource. Developing furits also act as skins and compete with aphid-induced sinks for food supply. Aphid success in producing galls was increased 31% when surrounding female catkins were removed.

Biennial wormwood has become an important weed problem in the northern Great Plains, but little is known about its biology. Biennial wormwood seeds were collected from Fargo, ND, and Fergus Falls, MN, for field experiments in 1999 and 2000 to determine the influence of transplanting date on growth, biomass, and seed production. Seeds were seeded in a greenhouse every 2 wk, and seedling rosettes were transplanted to the field 2 wk after emergence from April 30 until September 15 to simulate season-long emergence. Weekly destructive subsampling started 2 wk after transplanting and ended on September 29 in both years. All seedlings that grew for at least 5 wk after transplanting produced flowers by mid- to late August of the same year. Late-transplanted seedlings with less than 5 wk of growth did not flower or survive the winter. Biennial wormwood biomass allocation patterns resemble those of an annual species, with about 15% of the total dry weight allocated to roots, 20% to stems, 25...

We investigated the combined effects of salinity and hydroperiod on seedlings of Rhizophora mangle and Laguncularia racemosa grown under experimental conditions of monoculture and mixed culture by using a simulated tidal system. The objective was to test hypotheses relative to species interactions to either tidal or permanent flooding at salinities of 10 or 40 g/l. Four-month-old seedlings were experimentally manipulated under

Arbuscular mycorrhizal fungi (AMF) and Trichoderma harzianum are known to affect plant growth and disease resistance through interaction with phytohormone synthesis or transport in the plant. Cross-talk between these microorganisms and their host plants normally occurs in nature and may affect plant resistance. Simultaneous quantification in the shoots of melon plants revealed significant changes in the levels of several hormones in response to inoculation with T. harzianum and two different AMF (Glomus intraradices and Glomus mosseae). Analysis of zeatin (Ze), indole-3-acetic acid (IAA), 1-aminocyclopropane-1-carboxylic acid (ACC), salicylic acid (SA), jasmonic acid (JA) and abscisic acid (ABA) in the shoot showed common and divergent responses of melon plants to G. intraradices and G. mosseae. T. harzianum effected systemic increases in Ze, IAA, ACC, SA, JA and ABA. The interaction of T. harzianum and the AMF with the plant produced a characteristic hormonal profile, which differed from that produced by inoculation with each microorganism singly, suggesting an attenuation of the plant response, related to the hormones SA, JA and ethylene. These results are discussed in relation to their involvement in biomass allocation and basal resistance against Fusarium wilt.Dual inoculation with arbuscular mycorrhizal fungi and Trichoderma harzianum results in a plant hormonal profile different from that associated with the inoculation with either agent applied singly.► Mycorrhizal establishment and Trichoderma harzianum–plant interaction imply changes in the shoot hormonal profile of melon plants. ► Colonisation of different AMF produces common and divergent plant responses. ► T. harzianum effected systemic increases in Ze, IAA, ACC, SA, JA and ABA shoot content. ► Co-inoculation with T. harzianum and AMF produces a characteristic shoot hormonal profile, which differs from that produced by single inoculation.

Large interspecific differences exist in the potential relative growth rate (RGR) of plants. Which physio- logical, morphological, chemical and/or allocation-related factors explain this variation in growth rate? In a first experiment growth of eight herbaceous wild species was analysed, varying twofold in RGR. No correlation was found between RGR and the rate of photosynthesis per unit leaf area. The growth