Phenotypic plasticity and growth temperature: understanding interspecific variability

The subject of this review is the impact of long-term changes in temperature on plant growth and its underlying components. The discussion highlights the extent to which thermal acclimation of metabolism is intrinsically linked to the plasticity of a range of biochemical and morphological traits. The fact that there is often a trade-off between temperature-mediated changes in net assimilation rates (NAR) and biomass allocation [in particular the specific leaf area (SLA)] when plants are grown at different temperatures is also highlighted. Also discussed is the role of temperature-mediated changes in photosynthesis and respiration in determining NAR values. It is shown that in comparisons that do not take phylogeny into account, fast-growing species exhibit greater temperature-dependent changes in RGR, SLA, and NAR than slow-growing plants. For RGR and NAR, such trends are maintained within phylogenetically independent contrasts (i.e. species adapted to more-favourable habitats consistently exhibit greater temperature-mediated changes than their congeneric counterparts adapted to less-favourable habitats). By contrast, SLA was not consistently more thermally plastic in species from favourable habitats. Interestingly, biomass allocation between leaves and roots was consistently more plastic in slow-growing species within individual phylogenetically independent contrasts, when plants were grown under contrasting temperatures. Finally, how interspecific variations in NAR account for an increasing proportion of variability in RGR as growth temperatures decrease is highlighted. Conversely, SLA played a more dominant role in determining interspecific variability in RGR at higher growth temperatures; thus, the importance of SLA in determining interspecific variation in RGR could potentially increase if annual mean temperatures increase in the future.     

Growth temperature influences the underlying components of relative growth rate: an investigation using inherently fast- and slow-growing plant species

We examined the effect of growth temperature on the underlying components of growth in a range of inherently fast‐ and slow‐growing plant species. Plants were grown hydroponically at constant 18, 23 and 28 °C. Growth analysis was conducted on 16 contrasting plant species, with whole plant gas exchange being performed on six of the 16 species. Inter‐specific variations in specific leaf area (SLA) were important in determining variations in relative growth rate (RGR) amongst the species at 23 and 28 °C but were not related to variations in RGR at 18 °C. When grown at 18 °C, net assimilation rate (NAR) became more important than SLA for explaining variations in RGR. Variations in whole shoot photosynthesis and carbon concentration could not explain the importance of NAR in determining RGR at the lower temperatures. Rather, variations in the degree to which whole plant respiration per unit leaf area acclimated to the different growth temperatures were responsible. Plants grown at 28 °C used a greater proportion of their daily fixed carbon in respiration than did the 18 and 23 °C‐grown plants. It is concluded that the relative importance of the underlying components of growth are influenced by growth temperature, and the degree of acclimation of respiration is of central importance to the greater role played by NAR in determining variations in RGR at declining growth temperatures.     

Potassium requirements for growth and its related processes determined by plant analysis in wheat

Summary Potassium requirements for growth—dry matter (DM) and leaf area (LA) and related processes — relative leaf growth rate (RLGR), relative growth rate (RGR), net assimilation rate (NAR) and crop growth rate (CGR) were determined by plant analysis during the entogeny of wheat. Wheat (Triticum aestivum cv. HD 2329) plants were supplied with different amounts of K from deficient to adequate through nutrient solution. Samples were taken at specific stages for K determinations. The DM and LA were recorded at 45d, 75d and 105d. The growth related processes RGR, NAR and CGR were estimated between 30–45d, 45–75d and 75–105d. In case of RLGR the observations were carried out between 15–30d, 30–45d and 45–75d. These physiological processes and grain yield were correlated with K concentration in whole plant at 30 and 45d and top two leaves at 75 and 105d. The results indicated that k status in plants influences growth mostly through leaf area formation which inturn influences successively RLGR, RGR and CGR and finally grain yield. For vegetative growth the optimum concentration required in plants was always lower than the optimum for grain production.     

Effects of irradiation level on leaf growth of sunflower

Sunflower, Helianthus annuus L. cv. INRA 6501, plants were grown in a gravel culture subirrigated with Hoagland nutrient solution, at photosynthetically active radiation levels of 15, 30 and 60 W m^-2 at a daylength of 16 h, a temperature of 20°C and a relative humidity of 60% throughout. Development of the plant and growth of the leaves were measured. High irradiance accelerated development proportionally in all phases from germination, through leaf initiation, primordial flower formation and the maturation of all plant organs until anthesis. High irradiance levels stimulated the expansion of the growing shoot, which produced more and larger primordia. Under constant conditions the ratio between leaf initiation rate and mature length of a leaf remained constant, although the growth patterns [relationship between relative growth rate (RGR) and organ age] of successive leaves were not similar. Consequently, it may be assumed that, as in poplar, the increasing size of the growing shoot reflects the increase of the vascular system of sunflower. The growth patterns of the leaves depend on the developmental stage of the plant and, in the young primordial stage, also on irradiance level. In the linear phase of growth the growth pattern is independent of irradiance level.     

Growth of bean and tomato plants as affected by root absorbed growth substances and atmospheric carbon dioxide

Summary Bean and tomato plants were grown in solution culture root media containing pre-determined concentrations of gibberellin A₃ (GA), 1-naphthaleneacetic acid (NAA), N⁶-benzyladenine (BA), (2-chloroethyl)trimethylammonium chloride (CCC), and at atmospheric levels of 300 and 1000 ppm of CO₂. Net assimilation rates (NAR), relative growth rates (RGR), leaf area ratios (LAR), root to top dry weight ratios (R/T) and changes in dry weight, size, and form of each organ were recorded.Gibberellin had no effect on RGR of either plant species but increased the NAR of tomatoes at 1000 ppm CO₂. Total dry weight was only slightly affected by GA but root growth and R/T were markedly depressed. CCC had no effect on NAR, but decreased RCR and LAR. Root growth of beans and R/T in both plants were promoted by CCC. NAR and RGR were strongly inhibited by BA and NAA. Inhibition of stem and leaf growth by CCC and NAA was greater than that for roots; thus, R/T ratios were increased. Root branching was promoted by NAA.High (1000 ppm), compared to the low (300 ppm), atmospheric levels of CO₂ generally promoted root growth and produced an increase in the R/T, both in the absence and presence of chemical treatment. The multiplicity of effects of the rootabsorbed chemical growth substances and CO₂ on growth and photosynthesis is discussed.Journal article No 3883 of the Michigan Agricultural Experiment Station.NATO Fellow, University of Pisa, Italy.     

The effects of NaCl and CaCl2 on photosynthesis and growth of alfalfa plants

The effects of 0, 30, 60, and 90 mM NaCl, and 0 and 5 mM CaCl2 on certain parameters of photosynthesis and growth in alfalfa (Medicago sativa L. cv. Ghara yonjeh) plants were studied. The increasing NaCl concentration in the Hoagland nutrient solution decreased the contents of chlorophylls and the net photosynthetic rate, and increased the rate of respiration (RD) and CO2 compensation concentration in the leaves of treated plants. The contents of carotenoids (Car) were not significantly affected. The addition of 5 mM CaCl2 enhanced the RD and increased the Car contents in treated leaves. With the NaCl concentration in the culture medium increasing, the dry matter production in both root and shoot decreased, as well as the relative growth rate (RGR), net assimilation rate (NAR), and leaf area ratio (LAR). The addition of CaCl2 caused a partial elimination of the NaCl effects on the root and shoot, RGR and NAR, and it decreased the LAR.     

Solar irradiance level alters the growth of basil (Ocimum basilicum L.) and its content of volatile oils

The experiments were commenced in March 2003 and repeated in June 2003 at Sutton Bonington Campus, the University of Nottingham, UK, to investigate the effect of irradiance on plant growth and volatile oil content and composition in plants of basil. Four levels of irradiance were provided in the glasshouse, i.e. no shade (control), 25, 50 and 75% glasshouse irradiance. It suggested that basil grows well in full sun, however it can tolerate light shade. Heavy shading (75%) to provide a light integral of 5.3 moles m⁻² d⁻¹ resulted in shorter plants, lower weight, smaller leaf area, less shoots and higher specific leaf area, and also strongly reduced the rate of photosynthesis. There was no difference in CO₂ assimilation rate between 24.9 moles m⁻² d⁻¹ light integrals (no shading) and 13.5 moles m⁻² d⁻¹ light integrals (25% shading). Shading effectively reduced leaf temperature when air temperature was less than 30 °C, but heavy shading (75%) could not reduce leaf temperature when air temperature was above 36 °C due to a limitation of free air convection. Consequently, leaf temperature increased. Heavy shading strongly reduced total volatile oil content in fresh leaves, especially in older plants (shading treatment applied at the 3 leaf-pair growth stage). There were three chemical compounds in basil leaves, namely linalool, eugenol and methyl eugenol, influenced by the shading treatments. Linalool and eugenol, which contribute to the characteristic taste of basil, were significantly increased by high daily light integrals, whereas methyleugenol was increased by lower daily light integrals. No differences in the relative content of 1,8-cineole, one of the key aromatic compounds of Ocimum species, were observed.     

The effect of nitrogen nutrition on growth and biomass partitioning of annual plants originating from habitats of different nitrogen availability

Summary The hypothesis was tested that faster growth of nitrophilic plants at high nitrogen (N) nutrition is counterbalanced by faster growth of non-nitrophilic plants at low N-nutrition. Ten annual plant species were used which originated from habitats of different N-availability. The species' preference for N was quantified by the N-number of Ellenberg (1979), a relative measure of nitrophily. The plants were cultivated in a growth cabinet at five levels of ammonium-nitrate supply. At low N-supply, the relative growth rate (RGR) was independent of nitrophily. At high N-supply, RGR tended to be higher in nitrophilic than in non-nitrophilic species. However, the response of RGR to N-supply was strongly and positively correlated with the nitrophily of species. Increasing N-supply enhanced partitioning to leaf weight per total biomass (LWR) and increased plant leaf area per total biomass (LAR). Specific leaf weight (SLW) and LWR were both higher in non-nitrophilic than in nitrophilic species at all levels of N-nutrition. NAR (growth per leaf area or net assimilation rate) increased with nitrophily only under conditions of high N-supply. RGR correlated positively with LAR, irrespective of N-nutrition. Under conditions of high N-supply RGR correlated with SLW negatively and with NAR positively.     

Growth Analysis of Sweet Pepper (Capsicum annuum L.): 1. The Influence of Irradiance and Temperature under Glasshouse Conditions in Winter

A growth analysis was carried out with sweet pepper grown ina glasshouse. The plants received natural daylight or additionalillumination applied either during or after the natural photopenod.All irradiance conditions were applied at three temperatureregimes. Additional illumination increased leaf number, leaf area andtotal dry weight. At all temperatures the long-day treatmentsshowed a smaller number of leaves, but a larger leaf area whencompared to the short-day treatments with the same daily radiationsum. A lower temperature progressively reduced leaf area. The derived growth analysis quantities showed strong ontogenetictrends. When comparing both methods of applying additional illuminationhigher mean relative growth rates were observed for the long-daytreatments, especially at the lowest temperature. No differencesin mean net assimilation rate were found, but the short-daytreatments showed a reduced mean leaf area ratio. A lower nighttemperature decreased RGR and NAR but did not affect LAR, alower day temperature increased NAR and decreased LAR. Changesin LAR were largely mediated by changes in specific leaf weight. Capsicum annuum L., sweet pepper, growth analysis, irradiance, temperature     

Photosynthetic responses of <Emphasis Type="Italic">Chrysanthemum morifolium</Emphasis> to growth irradiance: morphology,anatomy and chloroplast ultrastructure

Seedlings of Chrysanthemum, cultivar ‘Puma Sunny’, were grown under a range of shading regimes (natural full sunlight, 55, 25, and 15% of full sunlight) for 18 days. Here, we characterized effects of varying light regimes on plant morphology, photosynthesis, chlorophyll fluorescence, anatomical traits, and chloroplast ultrastructure. We showed that leaf color was yellowish-green under full sunlight. Leaf area, internode length, and petiole length of plants were the largest under 15% irradiance. Net photosynthetic rate, water-use efficiency, PSII quantum efficiency, and starch grain were reduced with decreasing irradiance from 100 to 15%. Heavy shading resulted in the partial closure of PSII reaction centers and the CO₂ assimilation was restricted. The results showed the leaves of plants were thinner under 25 and 15% irradiance with loose palisade tissue and irregularly arranged spongy mesophyll cells, while the plants grown under full sunlight showed the most compact leaf palisade parenchyma. Irradiance lesser than 25% of full sunlight reduced carbon assimilation and led to limited plant growth. Approximately 55% irradiance was suggested to be the optimal for Chrysanthemum morifolium.     

Modelling the relative growth rate as a function of plant nitrogen concentration

The relationship between the relative growth rate (RGR) and the nitrogen concentration of the whole plant (PNC) was analyzed by using experimentally determined relations (1) between the PNC and the fraction of dry matter (LWR) and nitrogen in leaves, (2) between the specific leaf area (SLA) and the leaf nitrogen concentration (LNC) and (3) between the net assimilation rate (NAR) and the LNC on an area basis. A strong dependence of RGR on nitrogen concentration resulted from the increase in NAR, LWR and SLA with increasing PNC. A curvilinear relationship between RGR and PNC gave an optimum curve for nitrogen productivity against PNC.     

Photomorphogenesis and photoassimilation in soybean and sorghum grown under broad spectrum or blue-deficient light sources

The role of blue light in plant growth and development was investigated in soybean (Glycine max [L.] Merr. cv Williams) and sorghum (Sorghum bicolor [L.] Moench. cv Rio) grown under equal photosynthetic photon fluxes (approximately 500 micromoles per square meter per second) from broad spectrum daylight fluorescent or blue-deficient, narrow-band (589 nanometers) low pressure sodium (LPS) lamps. Between 14 and 18 days after sowing, it was possible to relate adaptations in photosynthesis and leaf growth to dry matter accumulation. Soybean development under LPS light was similar in several respects to that of shaded plants, consistent with an important role for blue light photoreceptors in regulation of growth response to irradiance. Thus, soybeans from LPS conditions partitioned relatively more growth to leaves and maintained higher average leaf area ratios (mean LAR) that compensated lower net assimilation rates (mean NAR). Relative growth rates were therefore comparable to plants from daylight fluorescent lamps. Reductions in mean NAR were matched by lower rates of net photosynthesis (A) on an area basis in the major photosynthetic source (first trifoliolate) leaf. Lower A in soybean resulted from reduced leaf dry matter per unit leaf area, but lower A under LPS conditions in sorghum correlated with leaf chlorosis and reduced total nitrogen (not observed in soybean). In spite of a lower A, mean NAR was larger in sorghum from LPS conditions, resulting in significantly greater relative growth rates (mean LAR was approximately equal for both light conditions). Leaf starch accumulation rate was higher for both species and starch content at the end of the dark period was elevated two- and three-fold for sorghum and soybean, respectively, under LPS conditions. Possible relations between starch accumulation, leaf export, and plant growth in response to spectral quality were considered.     

Net Assimilation Rate Determines the Growth Rates of 14 Species of Subtropical Forest Trees

Growth rates are of fundamental importance for plants, as individual size affects myriad ecological processes. We determined the factors that generate variation in RGR among 14 species of trees and shrubs that are abundant in subtropical Chinese forests. We grew seedlings for two years at four light levels in a shade-house experiment. We monitored the growth of every juvenile plant every two weeks. After one and two years, we destructively harvested individuals and measured their functional traits and gas-exchange rates. After calculating individual biomass trajectories, we estimated relative growth rates using nonlinear growth functions. We decomposed the variance in log(RGR) to evaluate the relationships of RGR with its components: specific leaf area (SLA), net assimilation rate (NAR) and leaf mass ratio (LMR). We found that variation in NAR was the primary determinant of variation in RGR at all light levels, whereas SLA and LMR made smaller contributions. Furthermore, NAR was strongly and positively associated with area-based photosynthetic rate and leaf nitrogen content. Photosynthetic rate and leaf nitrogen concentration can, therefore, be good predictors of growth in woody species.     

Patterns of dynamic irradiance affect the photosynthetic capacity and growth of dipterocarp tree seedlings

In the deeply shaded understorey of S.E. Asian rain forests the growth and survival of dipterocarp seedlings is limited by their ability to maintain a positive carbon balance. Photosynthesis during sunflecks is an important component of carbon gain in understorey plants. To test the sensitivity of photosynthesis and growth to variation in the pattern of dynamic irradiance, dipterocarp tree seedlings (Shorea leprosula and Hopea nervosa) were grown for 370 days under shaded forest light treatments of equal total daily photosynthetic photon flux density (approximately 3.3 mol m(-2) day(-1)), but characterised by either long flecks (LF) or short flecks (SF). Seedling growth was more than 4-fold greater under LF, compared with SF, in both species. Variation in the relative growth rates (RGR) and light saturated rates of photosynthesis (A(max)) were strongly positively correlated with the mean duration of sunflecks. Variation in RGR was strongly correlated with greater unit leaf rate growth, indicating that photosynthetic carbon gain per unit leaf area was greater under LF. The accumulation of starch in leaves over the diurnal period was 117% greater in both species under LF, compared with SF. Greater carbon gain in seedlings under LF is likely to have resulted from the combination of (1) greater A(max) (S. leprosula 35%, H. nervosa 40%), (2) more efficient dynamic photosynthesis, and (3) greater incident photosynthetic quantum yield, compared with seedlings receiving the SF irradiance treatment. The pattern of dynamic irradiance received by seedlings may significantly impact their growth and survival to a previously unrecognised extent, with important consequences for regeneration processes and hence forest structure and composition.     

Effects of virus infection and growth irradiance on fitness components and photosynthetic properties of Eupatorium makinoi (Compositae)

We examined the effects of geminivirus infection on fitness components and on photosynthetic properties of the host plant, Eupatorium makinoi, grown at two irradiance levels in a natural-light greenhouse. Under the low-light condition (13% full sunlight), more than a half of the infected plants died during the 9-mo experiment, while most of uninfected plants survived. Growth rate was also lowered by infection. At high light (50% full sunlight), by contrast, virus infection did not cause mortality despite slight decrease in growth rate. Flowering occurred only at high light, and reproductive outputs of the plants were markedly reduced by the infection. Infected leaves had distinct yellow variegations and, when compared with uninfected leaves, they showed (1) comparable light-saturated photosynthetic rate per unit area, but (2) lower initial slope of light-response curve of photosynthesis on an incident irradiance basis. The lower initial slope was mainly due to reduction of light-harvesting chlorophyll-protein complexes in the variegated parts. Since the differences in plant performance, depending both on infection and on growth irradiance, were largely explained by the differences in growth rate and/or plant size, the reduced photosynthetic production in the infected plants would be a major factor explaining the inferior performance of the host plants.     

Variation in growth stimulation by elevated carbon dioxide in seedlings of some C3 crop and weed species

Seven C₃ crop and three C₃ weed species were grown from seed at 360 and at 700 cm³ m^–3 carbon dioxide concentrations in a controlled environment chamber to compare dry mass, relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR) and photosynthetic acclimation at ambient and elevated carbon dioxide. The dry mass at the final harvest at elevated carbon dioxide relative to that at ambient carbon dioxide was highly correlated with the RGR at the lower carbon dioxide concentration. This relationship could be quite common, because it does not require that species differ in the response of RGR or photosynthesis to elevated carbon dioxide, and holds even when species differ moderately in these responses. RGR was also measured for a limited period at the end of the experiment to determine relationships with leaf gas exchange measured at this time. Relative increases in RGR at elevated carbon dioxide at this time were more highly correlated with the relative increase in NAR at elevated carbon dioxide than with the response of LAR. The amount of acclimation of photosynthesis was a good predictor of the relative increase in NAR at elevated carbon dioxide, and the long-term increase in photosynthesis in the growth environment. No differences between crops and weeds or between cool and warm climate species were found in the responses of growth or photosynthetic acclimation to elevated carbon dioxide.     

The Interrelated Effects of Stage of Development and Seasonal Changes in Light and Temperature on the Components of Growth in Zea mays

Seeds of Orla 266, a double cross hybrid of Zea mays, were sownin pots in the open 3, 6, and 9 weeks before the individualplants were sampled at consecutive weekly intervals from theend of August. On each occasion the weights of the whole plantand its parts plus leaf area were recorded, and the proceduresof growth analysis applied to the data. Between the youngest and oldest plants over all occasions thegreatest reductions with age were for the rate of leaf expansionand the ratio of leaf area to leaf weight. The net assimilationrate (NAR) and the leaf weight ratio (LWR) were depressed leastwhile the relative growth-rate (RGR) and leaf area ratio (LAR)occupied an intermediate position. The age effects were mostpronounced for RGR, NAR and the ratio of leaf area to leaf weightat the beginning of the experiment, whereas for LAR and LWRthe divergencies were largest at the end. On the basis of the recorded changes in solar radiation andtemperature and prior studies of the interacting effects oflight and temperature on the vegetative growth of Zea it waspossible to predict for the several growth components the patternsof change which should be expected. For the youngest and intermediatepopulations there was close agreement between the expected andobserved values for RGR, NAR, and LAR and it was concluded thatthe time courses were primarily dependent on environmental factors.On the other hand, for the oldest plants from the third intervalonwards the observed values for NAR and less so for RGR werematerially above expectation. It was noted that this divergencecoincided with the rapid extension of the shoot which was confinedto the oldest plants. It is advanced that the higher NAR isassociated with the vertical separation of the leaves.     

Growth Analysis and Reproductive Allocation of Japanese Forbs and Grasses in Relation to Organ Toughness under Trampling

Abstract: The growth and reproduction of Japanese forbs ( Artemisia princeps and Piantago asiatica ) and grasses ( Digitaria ad-scendens and Eleusine indica ) treated to 25 tramplings (3 g m^-2) per week were investigated in relation to the toughness (tensile strength) of organs. The perennial erect forb, A. princeps , was the most sensitive to trampling in terms of a remarkable depression of plant size and relative growth rate (RGR). RGR and net assimilation rate (NAR) of trampled A. princeps were negative. This was promoted by a loss of organs due to a reduced toughness of organs following trampling. In contrast to this species which did not flower after trampling, the perennial rosette forb, P. asiatica , maintained its plant biomass, NAR, RGR and reproduction under trampling because of tougher organs. However, NAR without trampling was lower in P. asiatica due to a larger leaf dry mass per leaf area (LMA), which could contribute to leaf toughness under trampling. The annual tussock grass, D. adscendens , which has a greater RGR than that of another grass, E. indica , without trampling was intolerant to trampling in terms of decreased biomass and RGR under trampling due to more sensitive organs, although it maintained an ability to reproduce. On the other hand, E. indica showed a marked trampling tolerance, with hardly reduced plant biomass and RGR. This species showed increased toughness of organs when trampled and frequently formed inflorescences in the growing period and produced similar biomass allocation to reproductive organs to untrarnpled plants. Between the grasses, RGR without trampling was slower in E. indica , partly because of its larger LMA. These results suggest that plants face a dilemma between trampling tolerance and efficient assimilative capacity and/or growth rate.     

Studies on the growth and development of Oxalis latifolia

The growth and development of Oxalis latifolia was assessed on outdoor-grown potted plants raised from bulbs. Three main phases of growth appeared to be correlated with major physiological developments in the aerial and subterranean organs. Establishment (weeks 1 – 5) was characterised by a slow gain in plant dry weight accompanied by high relative growth rate (RGR) values for individual plant organs. The second phase of growth (weeks 6 – 12) was reproductive, as stolons grew and initiated bulbils at the apices. Bulbils had the capacity to produce their own shoot system and ultimately some primary bulbils supported secondary bulbils. Dry matter accumulation was in the order: bulbils > peduncles > leaves > petioles > stolons = roots > parent bulb. The RGR of individual plant organs declined together with the net assimilation (NAR) rates and the leaf area ratio of the shoots during the reproductive phase and beyond into the senescence phase (week 13 onwards). The results are discussed in relation to the problem of achieving weed control via cultural and herbicide treatments.     

苗期遮光光质对生姜光合及生长的影响

以不同颜色塑料薄膜为遮光材料,研究了苗期遮光光质对生姜生长及光合作用的影响.结果表明:幼苗覆膜期,生姜叶片叶绿素含量以蓝膜及绿膜处理较高,白膜次之,红膜较低;叶片P_n则以绿膜处理较高,为14.9 μmol·m^-2·s^-1（第4叶）,分别较白膜、红膜及蓝膜提高5.7%、10.4%和18.3%.旺盛生长期撤膜后,P_n较幼苗期升高,但处理间的变化趋势与幼苗期相似;新生叶片叶绿素含量除红膜处理较低外,其它处理无显著差异,但下位叶片叶绿素含量则以蓝膜和红膜处理显著低于绿膜和白膜处理.蓝膜处理生姜植株茎秆增高、变细,分枝数较少;绿膜处理植株根、茎、叶及根茎鲜质量较高,白膜、红膜及蓝膜处理依次降低,收获时,其产量分别达57 000、53 709、51 487和48 712 kg·hm^-2.说明生姜苗期采用绿膜遮光,可增强叶片光合作用,促进植株生长,提高生姜产量.