A Physiological Approach to the Analysis of Crop Growth Data. II. Growth of Stylosanthes humilis

Crops of three ecotypes of the pasture legume Stylosanthes humiliswere grown during different lengths of growing season at Katherine,N T, Australia The ecotypes had contrasting flowering behaviour,and the interaction between their relative periods of vegetativeand reproductive growth and the length of the growing seasonwas studied A preliminary analysis, employing the techniques of traditionalgrowth analysis, was made of the data. The results were equivocaland a physiological approach to the analysis of the data wastaken From this second analysis it was concluded that the mainphysiological differences in the growth of the crops was theirflowering date and that differences in forage yield, and theyield of reproductive parts, at the end of the growing seasoncould be attributed to this factor No other consistent significantdifferences in the physiological behaviour of the crops wereobserved crop growth, mathematical model, Stylosanthes humilis, legume     

Germination of salt-stressed seeds as related to the ethylene biosynthesis ability in three Stylosanthes species

Stylosanthes, a genus of tropical forage legume, is known to exhibit good persistence in saline soils, yet mechanisms for regulation of seed germination under salt stress are poorly understood. This study was carried out to evaluate the mode of action of salt stress on seed germination of Stylosanthes. 1-Aminocyclopropane-1-carboxylic acid (ACC) increased ethylene biosynthesis and germination of NaCl-inhibited seeds in a dose-dependent manner. Contents of ACC and germination of Stylosanthes humilis seeds increased following transfer from NaCl solution to deionised water, but not after transfer to l-α-(2-aminoethoxyvinyl)-glycine (AVG) solution, an inhibitor of ethylene biosynthesis. Ethylene biosynthesis was much larger in NaCl-treated seeds of Stylosanthes guianensis than in seeds of S. humilis and Stylosanthes capitata, a fact which was reflected in higher germination rates. S. guianensis seedlings also displayed higher growth and survival rates than S. humilis and S. capitata under salt stress. Moreover, smaller ACC levels, as well as reduced ethylene biosynthesis of S. capitata seeds were accompanied by lower germination under salt stress. In addition, S. capitata seedlings treated with NaCl solutions exhibited relatively lower growth and survival rates in comparison with S. humilis and S. guianensis. Thus, different abilities to synthesize ethylene by S. guianensis, S. humilis and S. capitata seeds explain the differences in tolerance to salt stress of the three species.     

Growth responses of Stylosanthes humilis (Fabaceae) populations to saline stress

The growth responses to salinity of seedlings of six populations of Stylosanthes humilis from three ecogeographic regions of Northeast Brazil, characterized by wet or semi-arid climate, were analyzed following 28 days in solution cultures at concentrations of 0, 40, 80 and 120 mM NaCl. Root and shoot mass, shoot length and characters of foliar damage (number of leaves with chlorosis and necrosis) of the populations were more affected by increasing NaCl than numbers of leaves and branches and root length. Although S. humilis has been considered a salt sensitive legume, significant differences in salt tolerance between populations were found. The estimated concentrations which reduced shoot dry mass by 50 and 25% varied between populations from 84 to 108 and from 49 to 83 mM NaCl, respectively. Salt tolerance in S. humilis during the initial growth stage was lower than the reported one for germination. With one exception, populations from semi-arid climate with saline soils showed higher salt tolerance than those from non saline soils. The results suggest that salt tolerance in these populations is mainly associated with the occurrence of salinity in the soil of their provenance.     

An Analysis of Spatial Variation in the Nitrogen Content of Leaves from Different Horizons Within a Canopy

An analysis of spatial variation in the specific nitrogen contentof leaves from different positions within a canopy is developed.It is used to examine data obtained for contrasting crop species;the legume crop guar (Cyamopsis tetragonoloba), and crops ofa forage sorghum. The analysis distinguishes two componentsof the leaf nitrogen content: one associated with the metabolicapparatus within the leaf tissues and the other with structuralelements of the leaf. The analysis allows the spatial variationin specific leaf nitrogen content to be quantitatively described. Leaf nitrogen content, crop growth, light interception     

Efficient transformation with regeneration of the tropical pasture legumeStylosanthes humilis usingAgrobacterium rhizogenes and a Ti plasmid-binary vector system

Agrobacterium rhizogenes carrying the binary Ti plasmid vector pGA492 was used to transform leaf and stem explants of the tropical pasture legumeStylosanthes humilis. Conditions which yielded kanamycin resistant roots at a frequency of up to 86% and subsequent plant regeneration at a frequency of 23% were defined. Transgenic plants were fertile and either grew normally or had stunted growth but otherwise showed only minor morphological abnormalities. Transgenic plants with normal phenotypes were obtained in the progeny of the primary regenerants. The presence of active neomycin phosphotransferase enzyme activity and binary vector DNA and TL-DNA was demonstrated in the regenerated plants. Evidence for the independent transfer of binary vector and TL-DNA was also obtained. This high frequency production of transgenic plants ofS. humilis is a major improvement over previous methods using disarmed strains ofA. tumefaciens as helper.     

Breaking dormancy of <Emphasis Type="Italic">Stylosanthes humilis</Emphasis> seeds with low pH solutions

An acidic condition (low pH) of the germination media promoted dormancy breakage of scarified seeds of Townsville stylo (Stylosanthes humilis H.B.K.), an annual tropical forage legume, whether produced by either an unbuffered (HCl-KOH) or a buffered (phthalate, McIlvaine) medium. Except for aminooxyacetic acid, all ethylene biosynthesis inhibitors tested and supplied with the low pH solutions decreased germination to variable extents. Low pH-stimulated dormant seeds produced ethylene 4-fold as much than untreated seeds. Production of ethylene by seeds treated with high pH solutions, which did not affect their dormant state, was also very low.     

Development of Floral Apex After Floral Induction in Stylo (Stylosanthes guianensis (Aubl.) Sw. var. guianensis)

The apex morphology of stylo (Stylosanthes guianensis var. guianensis)is described in four developmental phases (vegetative, transitional,initiated and floral) further subdivided into a total of tenstages. The apical dome broadens and flattens as induction proceedsuntil the initiation phase when apical diameter within 0.05mm of the dome apex is 55 per cent greater than in the vegetativeapex. Changes in vegetative morphology during induction aredescribed. Stylosanthes guianensis var. guianensis, stylo, flowering, reproductive anatomy, developmental stages     

A Simple Phenological Model of Muskmelon Development

Utilizing information gathered in previous growth chamber andfield experiments, we developed a simple temperature-drivencrop phenology model of muskmelon (Cucumis melo L.) to helpcommercial growers time crop phenological events and predictharvest dates. The model quantifies vegetative development interms of main vine node numbers which allows the model to simulateeither a direct-seeded or a transplanted crop. The model operateson an hourly time-step but requires only daily weather dataand a few cultivar-specific parameters including plastochroninterval and thermal time requirements to reach six predefineddevelopmental stages. The model was tested against an independentdata set consisting of three muskmelon cultivars grown at fivetransplanting dates. Tests of the model indicate an averageability to predict main vine node numbers to within one to twonodes of observed values. Estimated harvest date predictionswere more variable than those for main vine node number butan average model accuracy of 1 to 3 d was obtained in modeltests with a data set used to construct the model. Proceduresfor calibrating the model for different cultivars, culturalpractices or environments are outlined. Copyright 0000 Cucumis melo L., cantaloupe, temperature, model, thermal time, plastochron interval, growth duration     

On the Ordered Development of Plants 3. Branching by the Grain Legume Cyamopsis tetragonoloba(Guar)

Two selections of guar (Cyamopsis tetragonoloba (L.) Taub.)with contrasting branching patterns were grown at three plantdensities at two times of the year. The numbers of growing vegetativemeristems (branches and main stems) per unit ground area atthe start of reproductive growth were linearly related to theamount of the incident light energy intercepted by the differentcrops of each selection. The data were consistent with the hypothesisthat each vegetative meristem required a minimum assimilateflux to continue growth and, further, that meristems on thehighly branching selection required approximately one-quarterof the assimilate flux required by vegetative meristems on therelatively non-branching selection. The effect of increasingplant density in reducing branching by individual plants ofa particular selection was also consistent with this hypothesis. The hypothesis accounted quantitatively for the observed three-dimensionaldistribution of vegetative meristems through the volumes ofcrop canopies at each of the three plant densities. The implicationsof this analysis to the field performance of crops comprisingplants with different branching patterns are discussed. Cyamopsis tetragonoloba, guar, branching, grain legume, crop, morphology     

The Effect of Drying Rate on the Survival of Three Desiccation-tolerant Angiosperm Species

The effect of drying rate on the survival of three angiospermresurrection plants, Craterostigma wilmsii (homoiochlorophyllous),Xerophyta humilis (poikilochlorophyllous) and Myrothamnus flabellifolius(homoiochlorophyllous) was examined. All species survived slowdrying, but only C. wilmsii was able to survive rapid drying.C. wilmsii was rapidly able to induce protection mechanismssuch as folding of cell walls to prevent mechanical stress andcurling of leaves to minimize light stress, and thus survivedfast drying. Rapid drying of X. humilis andM. flabellifoliusappeared to allow insufficient time for complete induction ofprotection mechanisms. In X. humilis, there was incomplete replacementof water in vacuoles, the photosynthetic apparatus was not dismantled,plasma membrane disruption occurred and quantum efficiency ofphotosystem II (F_V/F_M) did not recover on rehydration. Rapidlydried leaves of M. flabellifolius did not fold tightly againstthe stem and F_V/F_Mdid not recover. Ultrastructural studies showedthat subcellular damage incurred during drying was exacerbatedon rehydration. The three species co-occur in environments inwhich they experience high desiccation pressures. C. wilmsiihas few features to retard water loss and thus the ability forrapid induction of subcellular protection is vital to survival.X. humilis and M. flabellifolius are able to retard water lossand protection is acquired relatively slowly. Copyright 1999Annals of Botany Company Chlorophyll fluorescence, Craterostigma wilmsii, drying rate, Myrothamnus flabellifolius, resurrection plant, ultrastructure, Xerophyta humilis.     

Dynamics of phytoplankton in the Great Barrier Reef Lagoon

The characteristics of the phytoplankton crop in the centralregion of the Great Barrier Reef were analyzed through two annualcycles together with basic oceanographic parameters. Chlorophylla standing crop and primary production were size fractionatedinto nanoplankton and microplankton components. Community compositionwas determined using the Utermöhl settling technique andcommunity diversities estimated by the Shannon-Weaver equation.The data and analysis are the most comprehensive in existencefor the region, and the first detailed study since the 1928–29Great Barrier Reef expedition. A marked seasonal cycle was identified,contrary to most assumptions, closely associated with precipitationpatterns and nutrients introduced by land drainage. The regionwould rank as mesotrophic with some eutrophic areas in the innerreaches of the Lagoon. Oscillatoria spp. accounted for a largefraction of the majority of phytoplankton maxima and were inverselyrelated to diatom crop densities even under conditions favoringdiatom growth. Microplankton crop species diversities usuallydecreased during extended Oscillatoria blooms. The reduced diversitypersisted after the bloom suggesting that Oscillatoria spp.were the source of extracellular metabolites and/or decompositionproducts adversely influencing diatom microplankton.     

Use of the Expolinear Growth Model to Analyse the Growth of Faba bean, Peas and Lentils at Three Densities: Predictive Use of the Model

The expolinear equation for crop growth (Goudriaan and Monteith,Annalsof Botany66: 695–701, 1990; Goudriaan, 1994. In: MonteithJL, Scott RK, Unsworth MH, eds.Resource capture by crops.Nottingham:Nottingham University Press, 99–110) has the potentialto predict growth under specified environmental conditions.The choice of suitable parameters is discussed and tested usingdata from field experiments with faba bean, peas and lentils(Ishag and Dennett,Annals of Botany82: 497–505. 1998).It is suggested that suitable parameters for predicting cropgrowth are the fraction of solar radiation intercepted at emergence,the extinction coefficient for solar radiation, the maximumfraction of radiation intercepted, the maximum relative growthrate and the maximum crop growth rate for a crop interceptingall the incident radiation. In the experiments considered, thedifferences in growth patterns were due mainly to differencesin the maximum relative growth rate associated with differencesin temperature.Copyright 1998 Annals of Botany Company Expolinear equation, grain legumes, crop growth rate, crop density, relative growth rate, growth modelling, faba bean,Vicia fabaL., peas,Pisum sativumL., lentils,Lens culinarsMedic.     

Day and Night Temperature Control of Floral Induction in Stylosanthes guianensis var. guianensis cv. Schofield

Floral initiation in seedlings of Stylosanthes guianensis var.guianensis cv. Schofield grown at a photoperiod marginal forflowering (12–11.75 h) was promoted by a combination oflow day (25 °C) and low night (16 or 21 °C) temperatures,and completely inhibited by a 35 °C day temperature. Additionally,earliness of floral initiation under naturally decreasing daylengthwas negatively related to temperature regime over the range35/30 to 20/15 °C (day/night). Stylosanthes guianensis var, guianensis, flowering, temperature, photoperiod, short-day plant     

Decreased peroxidase activity in transgenic tobacco and its effect on lignification

An antisense gene construct of a peroxidase gene (Shpx6a) from a tropical pasture legume Stylosanthes humilis was transferred into tobacco cells via Agrobacterium tumefaciens to test whether peroxidase activity could be decreased and what effect this would have on lignification. A large number of tobacco cell lines were regenerated on selective media and stable integration of the transgene was confirmed in randomly selected putative transformants. Analyses of the primary transgenic plants and their progeny (T ₁) demonstrated that the total peroxidase activity was significantly decreased (up to 36%) as compared to that measured in untransformed control plants. Importantly, reduction in peroxidase activity is accompanied by decreases (up to 23%) in lignin content in several transgenic lines.     

Stability of the Nitrogen Concentration of Inoculated White Lupins during Pod Development

The general pattern of decrease of the 'critical' plant N concentration(i.e. minimum concentration required for maximum growth rate)during growth has been described for several C₃ non grain-legumespecies, and this can be used as a reference curve for diagnosisof N nutrition in these species. The present study was undertakento investigate changes of N concentration during growth of agrain legume, in different conditions of N nutrition. Whitelupin (Lupinus albus L.) was grown for six crop seasons in fieldtrials in which inoculation with Rhizobium lupini, nitrogenfertilizer rate, cultivar and plant density were density weremanipulated. The yield and dry matter production of noninoculatedplants were lower than, or at the best similar to, those ofinoculated plants, whatever the level of N supply. From anthesisto the beginning of seed filling, the N concentration of shootsof inoculated plants was found to be remarkably stable betweenyears, N fertilization regimes, cultivars, and for individualplants within a plot. Nitrogen concentration only varied withplant density. By contrast, the N concentration of noninoculatedplants was highly variable and generally lower than that ofinoculated plants, whatever the level of N supply. The highand stable N concentration of inoculated plants did not appearto be necessary for maximum growth rate but seemed to be requiredfor maximum production of seed dry matter and N. The potentialuse of these results to diagnose, in any white lupin crop, aninefficiency of the lupin-R. lupini interaction is evaluated.Copyright1993, 1999 Academic Press Lupinus albus L., white lupin, N₂ concentration, inoculated plants, non-inoculated plants, N₂ fixation efficiency, diagnosis     

A flexible sigmoid function of determinate growth

A new empirical equation for the sigmoid pattern of determinate growth, 'the beta growth function', is presented. It calculates weight (w) in dependence of time, using the following three parameters: t(m), the time at which the maximum growth rate is obtained; t(e), the time at the end of growth; and w(max), the maximal value for w, which is achieved at t(e). The beta growth function was compared with four classical (logistic, Richards, Gompertz and Weibull) growth equations, and two expolinear equations. All equations described successfully the sigmoid dynamics of seed filling, plant growth and crop biomass production. However, differences were found in estimating w(max). Features of the beta function are: (1) like the Richards equation it is flexible in describing various asymmetrical sigmoid patterns (its symmetrical form is a cubic polynomial); (2) like the logistic and the Gompertz equations its parameters are numerically stable in statistical estimation; (3) like the Weibull function it predicts zero mass at time zero, but its extension to deal with various initial conditions can be easily obtained; (4) relative to the truncated expolinear equation it provides more reasonable estimates of final quantity and duration of a growth process. In addition, the new function predicts a zero growth rate at both the start and end of a precisely defined growth period. Therefore, it is unique for dealing with determinate growth, and is more suitable than other functions for embedding in process-based crop simulation models to describe the dynamics of organs as sinks to absorb assimilates. Because its parameters correspond to growth traits of interest to crop scientists, the beta growth function is suitable for characterization of environmental and genotypic influences on growth processes. However, it is not suitable for estimating maximum relative growth rate to characterize early growth that is expected to be close to exponential.     

Growth Parameters of Yield of Plantain (Musa cv. AAB)

The performance of the crop plant and the ‘ratoon’plant (lateral shoot succeeding the harvested main shoot) of65 medium-sized False Horn plantains (Musa cv. AAB) was studiedby measuring vegetative and inflorescence (bunch) parameters.From significant regressions between different parameters itappears that taller pseudostems produce leaves at a faster rate,flower earlier and produce heavier infructescences which needmore time to mature. A high yield is determined by vigorousinitial growth of the planted sucker (lateral root). Beforeflowering, there is no sink competition between ratoon and mainpseudostem growth, and fast-growing main pseudostems are accompaniedby fast-growing ratoons. After flowering, competition occursbetween the fructifying inflorescence, a preferential sink andthe ratoon. The results indicate that plantain should not beconsidered as an annual crop. Growth, development, production parameters, bananas, plantains     

Winter Growth of Autumn-sown White Lupin (Lupinus albus L.) Main Apex Growth Model

The winter growth of winter white lupin (cv. Lunoble) was investigated.Over three consecutive years, 1987–1989, it was sown atdifferent times at Lusignan (France) and in 1989, at nine differentlocations with various sowing times. The production of primordia,the vernalization requirements and the final number of leaveson the main stem were related to field measurements of dailymaximum and minimum temperatures. A statistical model for the main apex growth with a system oftwo equations was developed, with a threshold level for leafprimordia production at 3 °C. The number of leaf primordiaproduced by a vegetative apex (y) in terms of the cumulativesums of temperature over 3 °C (x) followed the curvilinearregression y = 4.76 + 00268x + 00000156x². The upper and lowertemperature limits for vernalization were estimated as 14 andI °C respectively. The vernalization requirements of a vegetative apex (y) decreasedwhen the number of initials produced (x) increased accordingto the negative exponential regression y = exp (7.2 + 002626.x). The two equations were used for the prediction of the finalnumber of leaves of a lupin crop. The predictive accuracy ofthe model was checked against independent data. The agreementbetween observed and predicted final leaf number was often close,but some deviations did occur with low leaf number. The modeldescribed most of the growth phenomena which occur during thephase sowing to floral initiation of the main stem of a winterlupin crop, and its possible uses are discussed. Lupinus albus L., white lupin, growth, model, vernalization, primordia, apex, thermal time     

A Comparison of Two Approaches for Modelling Cassava (Manihot esculenta Crantz.) Crop Growth

Two approaches for modelling the growth and development of cassava,Manihot esculenta Crantz, are described and evaluated. The twomodels differ only in the hypotheses accounting for storageroot growth. In model 1, assimilate allocation to storage rootsis governed by the combined Chanter's (1976: Mathematical modelsin mushroom research and production. PhD Thesis, Universityof Sussex, UK) growth equation; and in model 2 the spill-overhypothesis for assimilate allocation to storage root governsstorage root growth. In both models, canopy photosynthesis generatesthe carbon substrate required for all growth processes. Thegrowth rates of leaves, stems and storage roots are definedby growth equations subject to substrate saturation kinetics.A key feature of both models is that the growth demands of thestem, fibrous roots and storage roots are related to leaf demandrates. Allocation to stems and branches was modelled by meansof a modified logistic growth equation which includes all theparameters and variables (number of nodes, internode lengths,stem density, stem modulus of elasticity and branch tensilestrength) that define the limits of the load bearing capacityof the shoot's supportive structures. The correlation coefficientsfor determination of yield prediction for the models werer =0.898,P =0.0385 (model 1) and r =0.954, P =0.0117 (model 2). For agrowth season of 290 d (after which leaf area index equals zeroand crop growth ceases), both models simulate the sigmoidaltransition from the lag to exponential phase of crop growth.Both models are equally well corroborated by observed data;however, model 1 has greater explanatory power. Copyright 2000Annals of Botany Company Allocation, simulation, model, crop growth, cassava, Manihot esculenta Crantz.