摘要:

AbstractFour simulation models were tested for their suitability as a basic growth model in a decision support system for sugar beet growing in The Netherlands. SUCROS and SUBEMO are complex, mechanistic models; LINTUL and PIEteR are relatively simple regression models including causal relationships at a higher level of integration. All four models are dynamic, i.e. they calculate daily development and production rates.The selected model had to be able to predict root and sugar yields accurately and to correct for suboptimal water contents of the soil. It should be possible to include location‐specific data and new modules, e.g. for nitrogen fertilization or plant density. Finally, the farmer should be able to collect the required input data easily and cheaply.The tests showed that PIEteR predicted root and sugar yields best, partly because it contained water‐balance corrections, based on location‐specific soil characteristics. PIEteR could not be applied universally because of its regression character at a high level of integration, but it met the requirements spec

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1995.tb00215.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTall(Festuca arundmaceaSchreb.) and hard(Festuca ovinavar.longifolia(L.) Koch) fescues are widely sown to stabilize disturbed soils in the cool–humid and transition climatic zones of the USA. Our objectives were to: a) quantify changes in the allocation of dry matter and growth of tall and hard fescue, forced to grow on stored soil water in sandy soil; and b) compare dry matter allocation over time between roots and shoots to evaluate the dynamics of root‐associated drought avoidance mechanisms. A randomized complete block experiment with four replications and two factors (species and stress level) was conducted in a greenhouse. The main blocks consisted of two fescue species: tall fescue and hard fescue; sub‐blocks contained stress levels: well‐watered and stressed. Low, medium and severe stresses were imposed by withholding water in one set of pots. The types of fescue species grown significantly affected leaf area (LA), plant height (PH), water use (WU), root length (RL), longest root (LR), root area (RA), shoot (SDB) and root dry biomass (RDB), and root:shoot ratio (R/S). Stress level affected PH, WU, LR and RL at low stress; WU, LR and RA at medium stress; LA, PH, SDB, WU, RL, LR, RA and R/S at severe stress. Tall fescue had greater LA, PH, WU, RA, RL, LR, SDB, RDB and R/S than hard fescue under all treatments. Stress reduced LA, PH, SDB, WU, RA, RL, LR and R/S. Significant correlations were obtained for LA with RL, WU, LR, PH. RA, SDB, RDB; RL with WU, LR, PH. RA, SDB. RDB; WU with LR, PH, RA, SDB, RDB; LR with PH. RA, SDB, RDB; PH with RA, SDB, RDB; RA with SDB, RDB; and SDB with RDB. In conclusion, hard fescue had a shallower root system, shorter plant canopy, slower growth, and transpired less water to make it more drought tolerant. Tall fescue, with a deeper root system, longer plant canopy, faster growth, and greater water transpiration, is less drought tolerant at medium and severe stresses. Root attributes strongly correlated with shoot attributes and can be considered for breeding programs promoting drought to

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1995.tb00216.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAn attempt has been made to study the interactive effect of elevated CO2and moisture stress on photosynthesis, growth and water relations ofBrassicaspecies using open top chambers. It was observed that plants responded to elevated CO2significantly under moisture stress condition mitigating the adverse effects on photosynthesis and growth ofBrassicaspecies. Relatively drought susceptible species, viz.B. campestrisandB. nigra, responded to elevated CC2markedly as compared to less sensitiveB. carinataandB. junceaplants. The water status of plants significantly improved under elevated CO2concentration possibly by increasing stomatal resistance and/or by increased root growth.

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1995.tb00217.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractInvestigations were carried out on semigley in the central River Drava valley (Northern Croatia) with the aim of establishing the fertilizing value of biopost, as a representative of organic fertilizers, and of organo, as a representative of organic‐mineral fertilizers, in comparison with mineral fertilizers and stable manure, the latter two being compared with each other as well regarding the yield and quality of flue‐cured tobacco leaf. Efficiency of the fertilizer types and rates applied was strongly affected by very adverse meteorological conditions, which often showed characteristics of severe drought. Nevertheless, under such conditions and despite the minimum rates applied, biopost and organo had a positive effect on the yield and quality of the flue‐cured tobacco leaf. In all cases, they had an obvious advantage over mineral fertilization, offering distinct possibilities of their application in the growing of flue‐cured tobacco. However, owing to its better fertilizing efficiency, combined organic and mineral fertilization might be justified, certainly also with respect to the economic aspect of the problem. The positive influence of biopost and organo on the higher participation of quality classes of flue‐cured tobacco leaf in comparison with mineral fertilization is indisputable despite the occasionally prevailing effects of fluctuating weather conditions during the investigation period. In other words, harmonic organic, even organic‐mineral, fertilization should be preferred to mineral fertiliz

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1995.tb00218.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA wheat cultivar (Condor) was grown in two experiments (thermal regimes 18/13 and 21/16°C) under low (298 μE m‐2:s‐1) radiation regimes during either an early phase from seedling emergence to terminal spikelet initiation (S2), a late phase from terminal spikelet initiation to anthesis (S2), or for the full period from seedling emergence to anthesis (S12), or high (560 μE m‐2s‐1) radiation throughout the growing period (S12) to determine whether developmental events are affected by radiation. The main developmental events considered in this study were the timing of terminal spikelet initiation and anthesis, the final number of leaf and spikelet primordia initiated in the apex and the rate of leaf appearance. Number of grains per spike and culm height were also measured.The duration of each phenophase was not affected by radiation intensity. Temperature affected the rate of wheat development, but the acceleration of development due to temperature during the seedling emergence ‐ terminal spikelet initiation phase only slightly reduced (from 24.8 to 23.2 days). Differences in time from terminal spikelet initiation to anthesis were greater than in the earlier phases, having been the duration reduced from 24.6 to 20.0 days due to high temperature.Associated with the lack of effect of radiation on phasic development and the negligible effect of temperature on the duration of the early phases of development, final Leaf number was practically unchanged in this study by either the radiation level or the growing temperature. Thus, radiation did not affect the rate of leaf initiation. The number of spikelets was affected by neither the treatments nor the thermal environment. The rates of leaf appearance were accelerated by temperature. Radiation, on the other hand, did not significantly alter the rates of leaf appearance in any of the treatments.As expected from many sources in the literature, the number of grains per spike was significantly affected by radiation during the phase from terminal spikelet initiation to anthesis. Due to the lack of significant effects of radiation on the developmental patterns of wheat, the changes in number of grains per spike were due to changes in the number of grains born in each spikelet.The results of the present study were compared with others available in the literature on the effects (or lack of them) of radiation and CO2concentration on phasic development, plastochron and phyllochron in wheat to reach the general conclusion that the rate of developmental events in wheat, in contrast to other plants, is almost completely independent of the availability of assimilates, with a possible exception for the Equatori

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1995.tb00219.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe heterosis of leaf photosynthesis was studied on the main characters included in the range from CO2exchange rate (CER) to enzymatic activity using a remote cross F, rice. The CER was significantly higher than those of the parental strains, showing a 111 % heterosis effect on average; at the same time strong heterosis was observed for the leaf area production and growth. Also stomatal and mesophyll conductances increased in the F1rice, which may contribute to the increase in CER. Chlorophyll content (Ch1), soluble protein content (SPC) and ribulose 1,5‐bisphosphate (RuBP) carboxylase activity (RCA) were measured as the internal factors related to photosynthesis, and compared between the F1, rice and the parents. For all these factors, the F1rice showed low values compared to the parents. Positive heterosis was not expressed here. On the other hand, the specific activity of RCA (RCA/SPC) increased in the F1, rice, showing a 120% heterosis effect. This may be regarded as one of the main causes for the increase in CER of the F1, rice. High CER expressed as heterosis concurrently with large leaf area production is one of the important findings in our study, and this may suggest a high possibility of further improvement in biomass production or yield of rice by gathering the advantageous elements into a hybrid plan

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1995.tb00220.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractExperiments were conducted in two consecutive years to investigate the response of two corn(Zea mays, L.)cultivars, Eperon and Challenger, to timing of N fertilizer in a desert climate. Fertilizer was applied three times (at planting, 6 weeks after sowing (6WAS) and at 9WAS) to give a seasonal total of 180 kg N ha‐1The N treatments were Nooo(control), NLOH(60 kg N ha‐1at planting, none at 6WAS and 120 kg N ha‐1at 9WAS), NLLL(60 kg N ha‐1at sowing, 6WAS and at 9WAS) and NLOH, (60 kgN ha‐1at planting, 120 kg N ha‐1at 6WAS and none at 9WAS). Generally, N ha‐1was associated with the highest grain and dry matter yields. Plants in N treated plots had significantly larger number of leaves and ear leaf N contents than the control at mid‐silk. High ear leaf N was associated with high leaf area index and dry matter yield. Based on these results, it would appear that the application of 60 kg N ha‐1at planting, followed by 120 kg N ha at 6WAS (NLHO) is the most suitable for enhancing corn yields in t

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1995.tb00221.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Book review in this articleHansen, A. P., Symbiotic N2 Fixation of Crop Legumes.Müller‐Sämann, K. M. and J. Kotschi, Sustaining Growth; Soil Fertility Management in Tropical Smallholding.Woomer, P. L. and M. J. Swift (eds.), The Biological Management of Tropical Soil Fertility.Jayas., D. S., N. D. G. White and W. E. Muir, Stored grain ecosystems.Opitz V. Boberfcid, W. Grunlandlehrc. Biologische und okologischc Grundlagen.Daniel, M. and R. P. Purkayastha (eds.). Handbook of Phytoalexin Metabolism and Action.Damania, A. B. (ed.). Biodiversity and Wheat Improvement.Colwell, J. D., Estimating Fertilizer Requirements‐A quantitative approach.Lenne, J. M. and P. Trutmann (eds.), Diseases of tropical pasture plants.O'Gara, F., D. N. Dowling, B. Boesten (eds.). Molecular ecology of Rhizopherc Microorganisms; Biotechnology and Release of GMOs.Wilkinson, R. E. (ed.), Plant‐Environment Interactions. Marcel Dekk

ISSN:0931-2250    

DOI:10.1111/j.1439-037X.1995.tb00222.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY