Growth and Nutrient Retranslocation in Needles of Radiata Pine in Relation to Nitrogen Supply

The effects of N application on tree growth and the retranslocationof N, P, and K from young needles to new growth were examinedin young radiata pine (Pinus radiata D. Don) trees. Nitrogen fertilization increased the number and size of needles,rates of shoot production, stem volume growth and tree biomass.Foliar N and P contents (µg per needle) fluctuated ina cyclic fashion with prominent phases of accumulation, retranslocationand replenishment. The patterns of these fluctuations in controland N-fertilized trees were similar, although the fluxes ofN, P and K in and out of needles were increased by N fertilization.Greater translocation (g per tree) of N and K from needles ofN fertilized trees occurred because fertilization increasedthe needle weight and the proportion of N and K retranslocatedfrom individual needles. Nitrogen fertilization increased theretranslocation of P largely as a result of higher needle mass.Trees supplied with more than adequate amounts of P in the soilretranslocated up to 58 per cent of the initial pool of P fromyoung needles. The periods of high retranslocation coincidedwith periods of high concentrations of soil mineral N and withshoot production. Conversely, the periods of rapid replenishmentof N and P into the needles coincided with the time of slowshoot growth and low concentration of soil mineral N. The growthrate of trees, rather than the availability of nutrients inthe soil was the main factor controlling retranslocation. For radiata pine, retranslocation from needles is not a mechanismspecific for coping with low soil fertility. It seems to bea mechanism which enhances the nutrient supply to apical growingpoints, especially during periods of flushing. Pinus radiata, nitrogen supply, shoot growth, nutrient fluctuations and retranslocation, nutrient use and adaptation     

Turnover of Carbohydrates in Relation to Growth in Apple Trees. I. Seasonal Variation of Growth and Carbohydrate Reserves

Growth in young apple trees of the rootstocks MM. 106 and M.7 was estimated by changes in d. wt., and growth in the differentregions of the two rootstocks was compared. Changes in d. wtwere compared with changes in extractable carbohydrates in MM.106 trees. The seasonal variations in d. wt, extractable carbohydratesand residues, are discussed in relation to utilization of reserveand current assimilates in the different regions of plant duringwinter, autumn, spring and summer. Malus sylvestris L, apple, carbohydrate, growth     

Competition Within Stands of Picea sitchensis and Pinus contorta

Competition was analysed in plots of Picea sitchensis and Pinuscontorta grown in 50 x 50 hexagonal arrays at 14 cm spacingto ages 7 and 5 years, respectively. Relative growth rates in height (RHGR) became positively relatedto tree heights during the year before harvest. Frequency distributionsof tree heights became negatively kurtotic with tendencies towardsleft-skew ness. By the time of harvest, dead trees were evenlydispersed over the plots. Trees with many taller neighbourshad lower RHGRs than trees with few taller neighbours, and theRHGRs of intermediate-sized trees were correlated with their‘competitive status’. Competition was confined mostlyto first-order neighbours. Large trees depressed the RHGRs ofsmaller neighbours and not vice versa; a simple test for this‘one-sided’ competition is described. Neighboursdid not need to greatly overtop a tree to depress its RHGR,they needed only to be at least as tall. Systematic trends inRHGR across the plots, attributed to site heterogeneity, decreasedwith time, and accounted for only about 10 per cent of the variationin RHGR at harvest. Competitive status accounted for 25 and38 per cent of the variation in RHGR in the Picea sitchensisand Pinus contorta plots, respectively. Picea sitchensis, Pinus contorta, competition, monoculture, self-thinning, relative growth rate, growth model     

Maintenance and Growth Components of Carbon Dioxide Efflux from Growing Pea Fruits

Carbon dioxide efflux from 5- to 20-day-old pea fruits was measuredfor plants grown in controlled environment at 15 °C and600 µmol s^–1 m^–2 photon flux density in a16 h photoperiod. The rate of CO₂ output per fruit increasedquickly from 0.005 to 0.018 mg CO₂ min^–1 during fruitelongation and subsequently more slowly to 0.030 mg CO₂ min^–1as the fruits inflated. On a d. wt basis the rate was highest,0.175 mg CO₂ g^–1 min^–1, in the youngest fruits anddeclined curvilinearly with increasing fruit weight to 0.02mg CO₂ g^–1 min^–1. Separation of maintenance andgrowth components was achieved by starvation methods and bymultiple regression analysis. From the latter method estimatesof the maintenance coefficient declined hyperbolically from150±8.7 mg carbohydrate g^–1 d. wt day^–1 inthe very young fruits (0.05 g) to 10.4±0.36 mg carbohydrateg^–1 d. wt day^–1 in older fruits (2.0 g). On a nitrogenbasis maintenance costs decreased from 2240 to 310 mg carbohydrateg^–1 nitrogen day^–1 while nitrogen concentrationfell from 6.7 to 3 per cent d. wt. A simple linear relationshipbetween maintenance cost per unit d. wt and nitrogen concentrationwas not observed. A growth coefficient of 50±6.7 mg carbohydrate g^–1growth (equivalent to a conversion efficiency, Y_G, of 0.95)was estimated for all fruits examined. The overall efficiency, Y, increased from a mean of 0.70 to0.85 during fruit elongation and subsequently declined to 0.80.For a given fruit weight, efficiency increased asymptoticallywith relative growth rate; both asymptote and slope of the relationshipincreased as the fruits grew. Pisum sativum L., garden pea, legume fruit, carbon dioxide efflux, maintenance respiration, growth respiration     

Changes in the Levels of Total Soluble Proteins and Sugars During Leaf Ontogeny in Stevia rebaudiana Bert.

Leaf d. wt and the levels of soluble sugars and proteins showa two-phase development during leaf growth in Stevia rebaudiana.The initial large increases in leaf size are due mainly to waterintake up to an area of around 9–10 cm². Increases inabsolute protein content were initially slow though in the secondphase increased it rapidly with dry matter and soluble sugarcontent. In relative terms, however, the concentration of free sugarsdeclined throughout leaf growth. The data indicate that leafprotein synthesis is most probably dependent upon a carbon supplyfrom in situ photo synthesis which only becomes significantat 80 per cent of full leaf area. Stevia rebaudiana Bert., leaf ontogeny, protein content, sugar content     

Changes of Starch and Sorbitol in Leaves Before and After Removal of Fruits from Peach Trees

Changes in contents of nonstructural carbohydrates in leaves,as well as some characteristics of leaves before and after fruitremoval, were investigated in potted peach (Prunus persica L.)trees. Leaf area and dry mass per unit leaf area (SLW) at thefruit-maturation stage decreased with increasing numbers ofpeaches per tree, whereas the chlorophyll content per unit areain leaves of fruiting trees increased. The chlorophyll contentdecreased more rapidly upon removal of fruit than that in leavesof fruiting trees. The starch content per unit dry mass in leavesof fruiting trees at the fruit-maturation stage was lower thanthat in leaves of non-fruiting trees. Starch accumulated significantlyin leaves within 1 d of removal of fruit during the fruit-maturationstage and continued to increase thereafter. The accumulationof starch after removal of fruit occurred more rapidly thanthe decrease in chlorophyll content. Reducing and non-reducingsugars (total sugars) per unit dry mass in the leaves were higherin fruiting trees than in non-fruiting trees. After fruit removal,the total sugar content of leaves increased temporarily andthen gradually decreased. The sorbitol content per unit freshmass in leaves of fruiting trees during the fruit-maturationstage was slightly higher than that in leaves of non-fruitingtrees. One day after removal of fruit, the sorbitol contentincreased in parallel with the accumulation of starch and remainedhigh. The sucrose content of leaves did not change markedlyupon removal of fruit. Prunus persica L.; peach leaves; nonstructural carbohydrate; starch and sorbitol; fruit removal     

Soya Bean Seed Growth and Maturation In vitro without Pods

Immature Glycine max (L.) Merrill seeds, initially between 50and 450 mg f. wt, were grown and matured successfully in vitro.Excised seeds were floated in a liquid medium containing 5 percent sucrose, minerals and glutamine in flasks incubated at25 °C under 300 to 350 µE m^–2 s^–1 fluorescentlight. During 16 to 21 d in culture, seeds grew to a matured. wt of 100 to 600 mg per seed at an average rate of 5 to 25mg d. wt per seed d^–1 depending on initial size. Growthrates were maximal during the first 8 to 10 d in vitro but declinedwith loss of green colour in the cotyledons. Seed coats rupturedwith rapid cotyledon expansion during the first 2 d in culture.Embryos were tolerant to desiccation and 80 to 90 per cent germinatedif removed from culture before complete loss of green colour.The growth of excised seeds in vitro exceeded the growth ofseeds in detached pods, but when windows were cut in pods topermit direct exposure of seeds to the medium, seed growth wascomparable. Glycine max (L.) Merrill, soya bean, seed culture, seed growth, seed maturation, germination     

Cell Cycle Responses to Red or Far-red Light, or Darkness, in the Shoot Apex of Silene coeli-rosa L. During Floral Induction

Twenty-eight-day-old plants of Silene coeli-rosa L. were maintainedin short days (SD) for 9 d (0–8) or exposed to 7 longdays (LD), or 7 SD with a 5 min exposure at 1700 h of each dayto far-red (FR), red (R) or 5 min FR/5 min R, or 7 dark-interrupted(di = 1700–1720 h) LD. Treatments were followed by twofurther SD. The mitotic index and G1 and G2 proportions weremeasured in the shoot apices of plants sampled at 2000 h ofeach day of each replicated treatment. Exposure to 7 LD (= 100per cent flowering) resulted in significant increases, relativeto the SD controls, in both the G2 proportion and the mitoticindex on d 0 to 3, 7 and 8. Five minute FR (= 0 per cent flowering)resulted in cell cycle responses similar to those in LD onlyfrom d 0 to 2. R and FR/R (both = 0 per cent flowering) didnot result in any increases in the G2 proportion in the apexapart from d 3 of FR/R. However 5 min FR/5 min R, and to a lesserextent 5 min R, did result in significant increases in the mitoticindex on d 0, 1, 7, and 8. diLD (= 8–10 per cent flowering)also prevented any significant increases in the G2 proportionon d 0 to 3, and 5 to 8 but the mitotic index was again higheron these days compared with control data. Thus the transitionto floral growth for 90 per cent of the plants is associatedwith changes in the cell cycle in the shoot apex measured asincreases in the G2 proportion at 2000 h of LD 0 to 3 and 7to 8. Silene coeli-rosa L., cell cycle, flowering, phytochrome, shoot apex     

Size-related flowering and fecundity in the tropical canopy tree species, Shorea acuminata (Dipterocarpaceae) during two consecutive general flowerings

We monitored the reproductive status of all trees with diameters at breast height (dbh) >30 cm in a 40-ha plot at Pasoh, west Malaysia, and investigated the individual fecundity of 15 Shorea acuminata Dyer (Dipterocarpaceae) trees using seed-trapping methods during two consecutive general flowering periods in 2001 (GF2001) and 2002 (GF2002). The proportion of flowering trees was higher, and not dependent on size, in GF2002 (84.2%), than in GF2001 (54.5%), when flowering mainly occurred in trees with a dbh ≤70 cm. Fecundity parameters of individual trees per event varied widely (221,000–35,200,000 flowers, 0–139,000 mature seeds, and 1.04–177 kg total dry matter mass of fruit (TDM) per tree). Monotonic increases with increasing tree size were observed for flower production and TDM amongst trees up to 90 cm in dbh, but not for mature seed production or for any of these parameters amongst larger trees. The pattern of reproductive investment during the two consecutive reproductive events clearly differed between medium-sized and large trees; the former concentrated their reproductive investment in one of the reproductive events whereas the latter allocated their investment more evenly to both reproductive events. Our results suggest size-related differences in the resource allocation pattern for reproduction. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Size-dependent Allometry of Tree Height, Diameter and Trunk-taper

The allometry of tree height with respect to trunk diameterand the allometry of trunk diameter with respect to distancefrom the top of the tree (i.e. trunk taper) were determinedfor 27 Robinia pseudoacacia trees differing in age and sizegrowing in an open field. The allometric (scaling) exponentfor height was > 1 for small and young trees and decreasedto 2/3 and then 1/2 as tree size and age increased. Similarly,the exponent for taper was > 1 near the tips of young andold trunks and converged onto values of 2/3 and 1/2 toward thebase of mature tree trunks. These observations indicate thata single 'optimal mechanical design principle' (i.e. elastic,stress or geometric self-similarity) neither holds true throughoutthe lifetime of R. pseudoacacia trees, nor does a single designprinciple govern the taper of a trunk throughout its entirelength. Rather, over the course of growth and development, theallometry of R. pseudoacacia tree height and trunk taper progressivelychanges, complying with geometric self-similarity for youngplants (and young portions of old plants) and subsequently givingthe appearance of elastic or stress self-similarity as plants(or portions of plants) get older and therefore larger. Analysesof published (and new) data suggest that the conclusions drawnfor R. pseudoacacia trees are likely to hold true for othertree species because stem growth in diameter is 'indeterminate'whereas growth in overall tree height is asymptotic and thereforeessentially 'determinate'.Copyright 1995, 1999 Academic Press Scaling, woody plants, Robinia pseudoacacia     

Loss of Viability in Lettuce Seeds and the Accumulation of Chromosome Damage under Different Storage Conditions

Loss of seed viability in lettuce (Lactuca sativa L.) duringstorage is associated with an increase in the frequency of cellsin the surviving seeds showing chromosome damage during firstmitoses. The relation is linear when probit of the frequencyof aberrant cells is plotted as a function of probit percentagenormal germination. The slope of the relation, however, variesaccording to moisture content so that the proportion of aberrantcells for any given loss of germination increases with decreasein moisture content over the range 13.0–5.5 per cent.At 3.3 per cent moisture content, however, the proportion ofaberrations was no greater than at 5.5 per cent moisture content;and at 18.1 per cent moisture content the proportion was noless than at 13.0 per cent moisture content. Despite these differences,the increase in chromosomal aberrations per unit time for agiven temperature was always less the lower the moisture content.Diplontic selection markedly reduced the frequency of chromosomalaberrations and eliminated the differences in these frequenciesbetween the different storage treatments. But even after fiveweeks' growth, root tips from aged seed still contained abouttwice as many aberrant cells as compared with similar root tipsderived from the original seed stock. Studies on the frequencyof recessive mutations indicated that excessive amounts of heritablemutations were not present in the progenies of aged seed, evenwhen stored at moisture contents as low as 5.5 per cent. Allthis and other evidence reinforces the view that orthodox seedsfor genetic conservation should be stored at not more than about5 per cent moisture content, and that even lower moisture contentsare worth considering. The results also emphasise the need formaintaining a high regeneration standard, i.e. the percentageto which seed viability is allowed to fall during storage beforethe seed stock is regenerated. Lactuca sativa, lettuce, seed storage, seed viability, chromosomal aberrations, phenotypic mutations     

Osmotic Stress as a Pregrowth Procedure for Cryopreservation: 1. Growth and Ultrastructure of Sycamore and Soybean Cell Suspensions

Sycamore and soybean cell suspensions were subjected to osmoticstress by culturing for one passage in media supplemented with6 per cent mannitol or sorbitol. The effects on growth wereto reduce cell number and biomass (d. wt) production throughoutthe culture period by about 30 per cent. Ultrastructural studiesat the early exponential phase of culture growth indicated similarreductions in cell wall thickness in both species. Osmoticallystressed sycamore cells became less vacuolate, but no such changeoccurred in stressed soybean cells. Acer pseudoplatanus L., sycamore, Glycine max L. var. Biloxi, soybean, suspension culture cells, osmotic stress, growth, ultrastructure     

Seed Production in Leafless and Conventional Phenotypes of Pisum sativum L. in Relation to Water Availability Within a Controlled Environment

Water requirements in relation to seed production was studiedin near-isogenic lines of leafless (afafstst) and conventional(++++) pea plants (Pisum sativum). The plants were grown toseed maturity in pots in a controlled environment under conditionsof high, medium and low irrigation levels. When each genotypewas irrigated independently and on demand and the soil moisturecontent maintained at 65–80 per cent of full capacitythere was no significant phenotypic difference in water useefficiency (WUE), defined as g d. wt seed per kg H₂O utilized.There existed genotypically-controlled upper and lower limitsto yield between which the total dry weight of seed per plantcan be determined by water availability. There was no significantdifferential effect of genotype or of irrigation treatment onthe number of pods, number of seed, unit seed dry weight andbiological yield per plant. There was significant interactionon stem length, and leaf area at specified nodes. When the wateractually required in relation to the water available was takeninto account, the leafless phenotype consistently utilized 33–38per cent less water and produced a correspondingly lower totaldry weight of seed than the conventional counterpart. Independentlyof regime the total dry weight seed per phenotype remained anear constant proportion of the above-ground biomass. Pisum sativum L., garden pea, leafless peas, seed production, water availability     

Developmental and physiological correlates of leaf size in Hyeronima alchorneoides (Euphorbiaceae)

The tropical emergent tree Hyeronima alchorneoides has large decreases in leaf size with tree age: 1200 cm(2) at 1 yr, 900 cm(2) at 3 yr, 200 cm(2) at 11 yr, and 80 cm(2) in old (>30 yr) individuals. We tracked leaf growth and physiological attributes on trees of three different ages (1, 3, and 11 yr) to determine the developmental basis and functional consequences of this variation. Leaves on young trees grew faster and sustained maximum rates of leaf expansion longer than leaves on older trees. Leaf mass per area (LMA) did not differ among age classes. Maximum photosynthetic rates reflected differences in leaf nitrogen concentration, in which leaves from the lower crown of younger trees outperformed those at a comparable crown position in older trees. One-year-old trees had the lowest stomatal conductance and the greatest instantaneous water use efficiency. Ontogenetic plasticity in mature leaf size, structure, and physiology may be a balance between the advantages conferred by rapid height growth when trees are young and the benefits derived from producing branches that increase light harvesting ability as trees reach the canopy.     

Individual resource allocation to vegetative growth and reproduction in subgenus <Emphasis Type="Italic">Cyclobalanopsis</Emphasis> (<Emphasis Type="Italic">Quercus</Emphasis>, Fagaceae) trees

The resource allocation for vegetative growth and female reproduction in three tree species of subgenus Cyclobalanopsis (Quercus, Fagaceae), i.e., Q. salicina, Q. sessilifolia, and Q. acuta, were examined on a per-individual basis in two consecutive reproductive seasons, in order to test whether these trees fit the predictions of the masting hypotheses about resource matching versus resource switching. Since the three Quercus species have a biennial fruiting habit, it takes 3 years for the observation of two reproductive events. Female flower and acorn production per tree were investigated by using a seed-trap method and a numerical analysis of seed dispersal. The net production of each individual was estimated as the sum of the annual increase in the dry mass of vegetative organs and reproductive investment per tree. In the data analyses, the three species were pooled, since all 12 sample trees of the subgenus apparently showed masting in the same year, with no exceptions. Female flower and acorn production per individual tree changed considerably between years. The net production per tree increased with tree size, but did not differ between years. Therefore, the reproductive allocation (proportion of a plant’s annual assimilated resources which are used for reproduction) differed dramatically between years. On the other hand, within a year, the reproductive allocation increased with increasing net production per tree. These results suggest that the switching of resource allocation between years within an individual are occurring in subgenus Cyclobalanopsis species, and the intensity of the switching increases with increasing tree size.     

新疆巩留野核桃林调查及其分析

新疆野核桃是我国珍稀的重要野生植物资源。在亚洲,成片分布仅在伊犁州巩留县野核桃沟自然保护区。为了更好地保护该珍贵资源,本研究对新疆巩留野核桃树的30cm处地径、树高、树皮光滑程度、树势、病(虫)害等方面进行调查,获取基础数据,并统计了野核桃沟不同沟系野核桃树的分布数量、幼树所占比例、病(虫)害分布状况。用树皮的光滑度分析其年龄结构,并进行野核桃树分布密度、年龄结构、生长势与环境的关系分析。结果显示,目前野核桃沟的野核桃树数量约有5500余株,30cm处地径小于10cm的幼树约占总株数的16%。分布在西沟和东沟的野核桃树约占总数的66%。野核桃林整体年龄结构基本合理,属于增长型群体结构。但病害的侵染,尤其是野核桃褐斑病、野核桃枝枯病的危害,严重影响了树木生长势。     

疏花对富士苹果光合同化物分配的外部调节和生理表现

在盛花期,利用对树冠不同部位疏除花序的试验。对富士苹果树体内同化物的调配及其生理表现进行了研究。结果表明,苹果平均单果重和平均单果叶面积之间关系呈线性正相关。该相关关系在不同处理之间无差异（r=0.91),充分说明在苹果树体内存在一个可自由流动的碳水化合物库或者说树体对结果具有光合调节作用,疏花可以从外部调节光合同化物分配的方向。对每株苹果树未结果部位和结果部位短枝及延长枝叶片净光合速率测定表明。结果和未结果部位光合速率没有显著差异。虽然疏花没有显著影响苹果单株枝条生长量和叶面积,但是,苹果树树冠全部疏除花序的一侧 或主枝的平均枝条生长量和叶面积去比该树其它结果部位分别平均高出153.5cm和8900cm^2,差异极为显著。苹果树疏除花序1/2或3/4的数量使苹果平均单果重比不疏花分别显著增加了33g或79g。而果实钙浓度每百克鲜重分别降低了1.62mg或2.66mg,充分说明当疏花显著地影响果实大小时,果实内钙浓度也会明显地发生相应的变化,虽然在疏花处理之间不同部位疏除花序没有影响单株花芽总数量,但是,每株树前一年春季疏花的部位比未疏花,结果的部位极显著地增加了花芽数量（SED=11.6)。     

The Effects of Shading on the Yield Components of Six 'Leafless' Pea Genotypes

The effect of unshaded, 30 and 80 per cent shade conditionson the growth rate and yield composition of six ‘leafless’pea (afaf: stst) genotypes has been determined. No evidencefor a photoassimilate source limitation was found in the unshadedand 30 per cent shade treatments, but 80 per cent shade significantlyreduced the yield and the rate of d. wt and node productionof all the genotypes. Yield development was followed in each environment by determiningthe number of flowering nodes, the number of flowers producedper node, the pod number per node and the seed number per pod.The theoretical maximum for each of these yield components wasdetermined and compared with the actual level realized by theplant. Approximately 50 per cent of the theoretical potentialof each yield component was realized and this appeared to beindependent of the shade treatment. This stepwise reductionin potential yield throughout the development of the plant wassimilar to that reported for conventional pea plants. Pisum sativumL, ‘leafless’ peas, shading, growth rate, yield'components, source limitation     

Effect of Calcium Chloride Concentration on Growth and Sporulation of Saprolegnia terrestris Cookson ex Seymour

As CaCl₂ concentration in the growth medium was reduced from27.4 to 0.107 µM the range of oospore number per oogoniumin Saprolegnia terrestris increased from 1 to 8 to 1 to 25 ormore, oospore size decreased and the precision of correlationbetween oospore number per oogonium and oogonial diameter decreased,but colony d. wt was not affected. The threshold CaCl₂concentrationrequired to give the lower range of oospore number per oogoniumwas independent of the concentration of other mineral nutrientsin the growth medium. The number of oogonia formed per unitarea of colony was affected by the concentration both of CaCl₂and of other mineral nutrients. Oospores formed in 0.107 µMCaCl₂ medium were often multinucleate but otherwise of normalappearance. The oospore abortion rate was increased from 3.09per cent at 27.4 µM CaCl₂ to 8.2 per cent at 0.107 µMCaCl₂. calcium, oogonia, oospores, Saprolegnia terrestris Cookson ex Seymour