Higher Relative Growth Rate Research Articles

Interactive Effects of N Form and P Concentration on Growth and Tissue Composition of Hybrid Napier Grass (Pennisetum purpureum × Pennisetum americanum).

This study aimed to assess effect of nitrogen (N) form and phosphorus (P) level on the growth and mineral composition of hybrid Napier grass. Experimental plants were grown with different N forms (NO3−, NH4NO3, and NH4+; 500 µM) and P concentrations (100 and 500 µM) under greenhouse conditions for 42 days. Growth rate, morphology, pigments, and mineral nutrients in the plant tissue were analysed. At the low P concentration, the better growth was found in the plants supplied with NH4+ (relative growth rate (RGR) = 0.05 g·g−1·d−1), but at the high P concentration, the NH4+-fed plants had 37% lower growth rates and shorter roots and stems. At the high P level, the NH4NO3−-fed plants had the highest RGR (0.04 g·g−1·d−1). The mineral nutrient concentrations in the plant tissues were only slightly affected by N form and P concentration, although the P concentrations in the plant tissue of the NO3−-fed plants supplied with the high P concentration was 26% higher compared to the low P concentration plants. The N concentrations in the plant tissues did not vary between treatments. The results showed that the optimum N form for the plant growth and biomass productivity of hybrid Napier grass depends on P level. Hybrid Napier grass may be irrigated by treated wastewater containing high concentrations of N and P, but future studies are needed to evaluate biomass production and composition when irrigating with real wastewater from animal farms.

Labour Market Adjustment and Intra-Industry Trade: Empirical Results from Indian Manufacturing Sectors

During the last two decades, India has witnessed several trade and industrial policy reforms. The objective of the study is to examine the relationship between dynamism of India’s two-way trade, measured through Marginal Intra-Industry Trade (MIIT) index, and labour market adjustments, reflected through absolute employment changes, in select manufacturing sectors over 2001–2015. India’s MIIT in select sectors generally display an upward trend over the sample period, while a mixed dynamics is observed on the employment front. The generalized method of moments (GMM) estimation results indicate that MIIT, increase in productivity, skilled workforce intensity, industrial concentration, incremental FDI inflows and trade openness positively influence absolute employment changes, whereas unskilled wage exerts a negative impact on the same. The analysis further concludes that high relative growth rate, skill-intensity, incremental FDI inflows and higher productivity in a sector, also characterized by higher MIIT, may lead the firms to employ more productive and competitive resources, resulting in higher absolute changes in employment. The obtained results do not support the Smooth Adjustment Hypothesis (SAH) predictions in the Indian context.

Growth and physiological characteristics of wasabi plantlets cultured by photoautotrophic micropropagation at different temperatures

In this study, wasabi plantlets were grown by photoautotrophic micropropagation under nine different day/night temperature regimes ranging from 10 °C/10 to 26 °C/26 °C. On day 28 of the culture, the dry weight and the leaf area were found to be highest under a constant air temperature of 18 °C/18 °C. Partitioning of plant biomass into stems increased whilst partitioning into leaves decreased with the increase in temperature. Whereas, partitioning of plant biomass into roots increased when the temperature increased from 10 to 18 °C but decreased with further increase in temperature to 26 °C. The shoot/root ratio showed an opposite trend compared with partitioning into roots, whereas the chlorophyll content of leaves increased when the temperature increased from 10 to 26 °C. The net photosynthetic rate of whole plantlets showed the same trend as plantlet biomass and was the highest in 18 °C/14 °C, 18 °C/18 °C, and 22 °C/18 °C treatments. By contrast, the value of the net photosynthetic rate per unit leaf area decreased sharply at temperatures ranging from 10 to 18 °C. A linear relationship between the net photosynthetic rate and RGR was clearly evident because of the large differences in the leaf area values. The specific leaf area of wasabi plantlets decreased slightly at temperatures ranging from 10 to 18 °C but increased substantially within the range of 18–26 °C; however, the leaf dry matter content showed an opposite trend. Low- and high-temperature ranges had contrasting effects on the leaf mass area and leaf nitrogen concentration. There was the high descent in dissolved oxygen concentration of culture medium at all treatments from day 0 to 7. Greater growth of wasabi plantlets in 18 °C/14 °C, 18 °C/18 °C, and 22 °C/18 °C treatments. Biomass allocation to leaves is more important than the net photosynthetic rate per leaf area for supporting a high relative growth rate.

Effects of Phosphorous Application on Growth Performance, Yield and Nutritional Value of Cockscomb (<i>Celosia argentea L</i>)

Effects of phosphorous (P) level on performance, yield and nutritional value of Celosia argentea L. were evaluated with the aim of determining the P level that supports the best growth, yield and nutritional qualities of the crop. The levels of P were: normal (1.348 mg·kg-1 of P/pot, NP), medium (6.743 mg·kg-1 of P/pot, MP), high (13.48 mg·kg-1 of P/pot, HP) and no P application (control, CP). The crop growth rate (CGR) increased with increase in phosphorus gradients (NP = 0.05 g/m2·d-1, MP = 0.09 g/m2·d-1 and HP = 0.12 g/m2·d-1). High and medium P rates increased the relative growth rate (RGR), HP had the highest RGR (0.05 g·g-1/day) followed by MP (0.04 g·g-1/day). Addition of P increased leaf area (LA) of C. argentea. Crude protein of the control was higher (5.56%) compared to the other P treatments (NP = 5.14, MP = 5.11 and HP = 5.03%). Phosphorus applications were beneficial for growth and enhancement of nutritional quality of C. argentea. NP and MP are recommended for growing this vegetablecrop.
 Keywords: Cockscomb, Chlorophyll, Crude fibre, Stress, Vegetable

Comparison on seed germination and seedling growth between Indonesian local corn cultivars for decide the quality of seed

Abstract. Wawo AH, Sumbogo VG, Lestari P. 2020. Comparison on seed germination and seedling growth between Indonesian local corn cultivars for decide the quality of seed. Biodiversitas 21: 3189-3199. Each region in Indonesia has local corn cultivars (Zea mays L), for example, South Sulawesi has some Pulut Pangkajene cultivars and Purbalingga, Central Java has Entog and Senggani cultivars. Compared to hybrid corn, local corn has its advantages such as dry resistance, short life, and specific taste. The identification of seed germination and seedling growth for Pangkajene corn (South Sulawesi), Entog and Senggani corns (Purbalingga) has not been performed, thus, specific characteristics to differ those three corn cultivars have not been available. The study aims to establish the characteristics of local corn cultivars, comprise the seed germination, seedling growth, and determine the best local corn cultivars for supporting food sources. This research has Factorial patterned with a Completely Randomized Design and it was repeated 4 times. The main factor is the germination facility, namely germination chamber and nursery house. Meanwhile, the second factors are corn cultivars, namely Pangkajene, Entog, and Senggani. The result shows that the Pangkajene and Entog cultivars have higher germinability and germination value compared to Senggani corn cultivar. Pangkajene and Senggani cultivars have higher seedling growth than Entog cultivar seedlings characterized by high relative growth rate (R) values. The Pangkajene cultivar has higher quality compared to 2 local corn cultivars of Entog and Senggani from Purbalingga (Central Java). Further, Senggani cultivars have higher quality than Entog cultivars.

Effects of three light intensities on the survival, growth performance and biochemical composition of two size giant clams Tridacna crocea in the Southern China Sea

Giant clams are able to grow in oligotrophic tropical marine environments with the aid of photosynthates from its symbiotic zooxanthellae. Therefore, light intensity affects the survival and growth of giant clams, and is one of the most important environmental factors in giant clam cultures. In this study, two size classes of Tridacna crocea (small: ~50 mm shell length, large: ~85 mm shell length) were cultured at three light intensities (5000, 10,000, and 15,000 lx) for 16 weeks, to evaluate the effects of light intensity on the survival, growth performance and biochemical composition of different size clams. T. crocea under 15,000 lx light intensity showed a significantly higher survival rate and relative growth rate (RGR) (P < .0001). The RGR in the small group was significantly higher than the large group under 10,000 and 15,000 lx light intensity (P < .0001), while higher RGR was observed in the large group under 5000 lx light intensity (P = .0009). The content of eight amino acids in the mantle was significantly affected by light intensity (P < .05), while only one amino acid (glycine) was found in the adductor muscle (P = .0005). Similarly, there were significant differences in ten mantle amino acids between small and large size groups (P < .05), while three amino acids were found in the adductor muscle (P < .05). C22:6n3 (DHA) was the major polyunsaturated fatty acid (PUFA) in T. crocea. In the adductor muscle, the C22:6n3 profile significantly increased with increasing light intensity and clam size (P < .0001), while no significant differences of C22:6n3 profiles were found among different light intensities in the mantle (P = .3345). Our results demonstrate that a light intensity of 15,000 lx is suitable for T. crocea (45–90 mm in shell length) rearing, and that large size T. crocea has higher tolerance to weak light intensity than small individuals.

Phenotypic Plasticity, Biomass Allocation, and Biochemical Analysis of Cordyline Seedlings in Response to Oligo-Chitosan Foliar Spray

Cordyline is one of the most important indoor pot plants and has a high request in the global market. As a bio-stimulant, chitosan could be used to enhance the plant growth and productivity, despite the variation in growth analysis and phenotypic plasticity of several plant species in response to chitosan supplement. Cordyline seedlings were foliar sprayed with five concentrations of oligo-chitosan (0, 25, 50, 75, and 100 mg L−1) for 4 months. Oligo-chitosan induced rapid growth of cordyline seedlings, in terms of larger specific leaf weight (SLW) and higher relative growth rate (RGRA), as well as improving the efficiency of plant photosynthesis (high net assimilation rate (NAR) or low specific leaf area (SLA)). Root growth rate (RGRR) has also increased by 89.13% with the application of 50 mg L−1 oligo-chitosan, which reflected on higher plant biomass (BM) in comparison to the control. Consequently, root biomass (RM) showed the greatest plasticity index (PPI) that enhanced growth, productivity, and quality as well as the marketability of cordyline seedlings. Foliar spray of 50 mg L−1 oligo-chitosan improved plant growth, root development, and plasticity index, resulted in increased quality and marketability of cordyline seedlings.

Persistence of Biological Control Agents in Waterhyacinth Following Herbicide Application

In Florida, waterhyacinth (Pontederia [Eichhornia] crassipes) (Martius) Solms Laubach (Pontederiaceae) is primarily controlled by herbicides, but overall control is enhanced by insect biological control agents that decrease growth and reproduction and slow regrowth. However, herbicide applications often disrupt the biological control agent populations when applied indiscriminately. Previous studies identified the utility of preserving populations of biological control agents in the vicinity of herbicide treated areas by establishing refuges for the insects. The objectives of this experiment were to quantify the impact of insect refuges, using groups of untreated P. crassipes within treated mats, on the regrowth of the new mat and the ability of biological control agents to persist following an herbicide treatment. Pontederia crassipes mats were grown with and without biological control agents, then treated with 2 concentrations of the herbicide penoxsulam. Plant growth metrics and biological control agent densities were monitored pre- and post-treatment and compared using ANCOVAs and non-parametric Kruskal-Wallis tests. Although the systemic activity of penoxsulam in the water column prevented the establishment of refuges in this study, biological control agent populations persisted following herbicide applications without additional releases and were able to remain at field densities after the decay and loss of P. crassipes. The treatment with no biological control agents and only half-label rate herbicide grew more densely, had greater dry weight biomass, higher relative growth rate, and produced more inflorescences than the plants in treatments with biological control agents. The half-label herbicide and biological control agent treatment performed as well as both treatments with label rate herbicide, and with and without biological control agents, respectively, in lowering P. crassipes density, final dry weight biomass, and relative growth rate. Although the concept of refuge systems at operational field scales requires further study, demonstrating the ability of biological control agents to persist even on sprayed mats is a necessary first step in determining the temporal and spatial factors that might influence the utility of such refuges.

Local adaptation of mycorrhizae communities changes plant community composition and increases aboveground productivity.

Soil microbial communities can have an important role in the adaptation of plants to their local abiotic soil conditions and in mediating plant responses to environmental stress. This has been clearly demonstrated for individual plant species, but it is unknown how locally adapted microbes may affect plant communities. It is possible that the adaptation of microbial communities to local conditions can shape plant community composition. Additionally, it is possible that the effects of locally adapted microorganisms on individual plant species could be altered by co-occurring plant species. We tested these possibilities in plant community mesocosms with soils and mycorrhizal fungi (AMF) from three locations. We found that plant community biomass responded positively to local adaptation of AMF to soil conditions. Plant community composition also changed in response to local adaptation of AMF. Unexpectedly, the strongest benefits of locally adapted AMF went to early successional plant species that have the highest relative growth rates and the lowest responsiveness to the presence of AMF. Late successional plants that responded positively overall to the presence of AMF were often suppressed in communities with local AMF, perhaps because of strong competition from fast growing plant species. These results show that local adaptation of soil microbial communities can shape plant community composition, and the benefits that plants derive from locally adapted microorganisms can be reshaped by the competitive context in which these associations occur.

Effects of benthivorous fish disturbance and snail herbivory on water quality and two submersed macrophytes

Benthivorous fish disturbance and snail herbivory are two important factors that determine the community structure of submersed macrophytes. We conducted an outdoor mesocosm experiment to examine the separate and combined effects of these two factors on water quality and the growth of two mixed-cultivation submersed macrophytes, Vallisneria natans and Hydrilla verticillata, with different growth forms. The experiment involved two levels of fish (Misgurnus anguillicaudatus) disturbance crossed with two levels of snail (Radix swinhoei) intensity. The results revealed that fish activity rather than snail activity significantly increased the overlying water concentrations of total suspended solids (TSS), total nitrogen (TN), ammonia nitrogen (N-NH4), total phosphorus (TP) and phosphate phosphorus (P-PO4). However, no differences among treatments were observed for chlorophyll a (chl a) concentrations. Fish disturbance or snail herbivory alone did not affect the relative growth rate (RGR) of H. verticillata, but their combined effects significantly decreased the RGR of H. verticillata. Although snail herbivory alone did not affect the RGR of V. natans, fish disturbance alone and the combined effects of these factors drastically reduced its RGR. Both species exhibited increased free amino acid (FAA) contents and decreased ramet numbers, soluble carbohydrate (SC) contents and starch contents in the presence of the fish. Moreover, compared to H. verticillata, V. natans showed exceedingly low ramet numbers and starch contents in the presence of the fish. H. verticillata had a higher RGR and summed dominance ratio (SDR2) than V. natans in all treatments; H. verticillata also displayed a larger competitive advantage in the presence of fish disturbance. The present study suggests that (1) fish disturbance rather than snail activity increases water nutrient concentrations, (2) low snail density may be harmful to submersed macrophyte growth when the plants are under other abiotic stress conditions and (3) the competitive advantage of H. verticillata over V. natans is more preponderant in a turbid environment.

Effect of Different Fruit Developmental Stages and Biochemical Metabolites of Pomegranate (Ponicaceae) on Life History Parameters of Ectomyelois ceratoniae (Lepidoptera: Pyralidae).

Plant-herbivore interactions can be influenced by plant developmental stages. Effects of four different developmental stages of pomegranate fruit (Hazelnut size, Walnut size, Juicy, and Ripe) were investigated on life table parameters, nutritional yield, and energy contents (protein, glycogen, and lipid) of Ectomyelois ceratoniae (Zeller) under controlled conditions in two pomegranate cultivars, namely Shahvare-Danesefid and Esfahani-Daneghermez as susceptible and resistant cultivars, respectively. Biochemical characteristics of the four developmental stages were determined, and a correlation was made with life-history and nutritional responses of E. ceratoniae. Significant differences were observed in developmental time and adult fecundity of E. ceratoniae across various tested stages in both pomegranate cultivars. The highest value of intrinsic rate of increase (rm) was found in Juicy and lowest in Hazelnut-size stage of Shahvare-Danesefid. The highest rm value was on Walnut-size and Juicy stages, and the lower rate was obtained from the feeding of E. ceratoniae on Ripe and Hazelnut-size stages in Esfahani-Daneghermez. A higher relative growth rate (RGR) was observed in Juicy (in Shahvare-Danesefid) and Walnut-size stages (in Esfahani-Daneghermez) when compared with other developmental stages tested. Life-history parameters of E. ceratoniae were correlated with biochemical qualities of pomegranate stages. Results indicated Juicy (Shahvare-Danesefid) and Walnut-size stages (Esfahani-Daneghermez) were relatively susceptible pomegranate stages, and Hazelnut-size and Ripe stages were unsuitable for feeding of E. ceratoniae in Shahvare-Danesefid and Esfahani-Daneghermez, respectively. Findings of this research could aid in the development of integrated management programs of E. ceratoniae in pomegranate orchards.

Effect of N supply on the carbon economy of barley when accounting for plant size.

Nitrogen availability and ontogeny both affect the relative growth rate (RGR) of plants. In this study of barley (Hordeum vulgare L.) we determined which growth parameters are affected by nitrate (N) availability, and whether these were confounded by differences in plant size, reflecting differences in growth. Plants were hydroponically grown on six different nitrate (N) concentrations for 28 days, and nine harvests were performed to assess the effect of N on growth parameters. Most growth parameters showed similar patterns of responses to N supply whether compared at common time points or common plant sizes. N had a significant effect on the biomass allocation: increasing N increased leaf mass ratio (LMR) and decreased root mass ratio (RMR). Specific leaf area (SLA) was not significantly affected by N. RGR increased with increasing N supply up to 1 mM, associated with increases in both LMR and net assimilation rate (NAR). Increases in N supply above 1 mM did not increase RGR as increases in LMR were offset by decreases in NAR. The high RGR at suboptimal N supply suggest a higher nitrogen use efficiency (biomass/N supply). The reasons for the homeostasis of growth under suboptimal N levels are discussed.

Low O2 level enhances CH4-derived carbon flow into microbial communities in landfill cover soils

CH4 oxidation in landfill cover soils plays a significant role in mitigating CH4 release to the atmosphere. Oxygen availability and the presence of co-contaminants are potentially important factors affecting CH4 oxidation rate and the fate of CH4-derived carbon. In this study, microbial populations that oxidize CH4 and the subsequent conversion of CH4-derived carbon into CO2, soil organic C and biomass C were investigated in landfill cover soils at two O2 tensions, i.e., O2 concentrations of 21% (“sufficient”) and 2.5% (“limited”) with and without toluene. CH4-derived carbon was primarily converted into CO2 and soil organic C in the landfill cover soils, accounting for more than 80% of CH4 oxidized. Under the O2-sufficient condition, 52.9%–59.6% of CH4-derived carbon was converted into CO2 (CECO2-C), and 29.1%–39.3% was converted into soil organic C (CEorganic-C). A higher CEorganic-C and lower CECO2-C occurred in the O2-limited environment, relative to the O2-sufficient condition. With the addition of toluene, the carbon conversion efficiency of CH4 into biomass C and organic C increased slightly, especially in the O2-limited environment. A more complex microbial network was involved in CH4 assimilation in the O2-limited environment than under the O2-sufficient condition. DNA-based stable isotope probing of the community with 13CH4 revealed that Methylocaldum and Methylosarcina had a higher relative growth rate than other type I methanotrophs in the landfill cover soils, especially at the low O2 concentration, while Methylosinus was more abundant in the treatment with both the high O2 concentration and toluene. These results indicated that O2-limited environments could prompt more CH4-derived carbon to be deposited into soils in the form of biomass C and organic C, thereby enhancing the contribution of CH4-derived carbon to soil community biomass and functionality of landfill cover soils (i.e. reduction of CO2 emission).

Effects of benthivorous fish disturbance on chlorophyll a contents in water and the growth of two submersed macrophytes with different growth forms under two light regimes

Low underwater light availability and benthivorous fish-mediated disturbance are two important factors that influence the growth of submersed macrophytes. However, the combined effects of these factors remain unclear. To determine the combined effects of low light and fish-mediated disturbance on the growth of two submersed macrophytes with contrasting growth forms, i.e., Vallisneria natans and Hydrilla verticillata, we conducted an outdoor mesocosm experiment with a two-by-two factorial design. The experiment involved two fish-mediated disturbance levels (0 and 1 Misgurnus anguillicaudatus) crossed with two levels of light intensity (ambient light and a low-light environment created by culturing the macrophytes under a shelter). The results showed that the chlorophyll a (chl a) concentration in the overlying water showed no difference among treatments for each macrophyte species. The fish-mediated disturbance significantly decreased the relative growth rate (RGR) of both species in the low-light environment but showed no effects in the ambient light environment. Low light availability and/or fish-mediated disturbance led to increased plant heights of both species compared with the heights under the ambient light regime. Low light availability combined with fish-mediated disturbance significantly reduced the ramet number and soluble carbohydrate (SC) content of both species; however, the free amino acid (FAA) content was not affected. Compared to V. natans, H. verticillata exhibited a high RGR and high ramet numbers in a low-light environment combined with fish-mediated disturbance. Our results indicated that the adaptability of H. verticillata is better than that of V. natans in turbid, shallow and hydrostatic water. Fish-mediated disturbance can negatively influence submersed macrophyte recovery in lakes when light is not abundant.

Short term effects of irradiance on the growth of Pterocladiella capillacea (Gelidiales, Rhodophyta)

Pterocladiella capillacea has been economically exploited for agar extraction in the Azores for many years. Harvesting dropped to a full stop in the early 1990s due to a population collapse, but restarted in 2013. Since then it has been intensively harvested and overexploitation must be prevented, with both sustainable harvesting and effective cultivation practices. This study represents the first attempt to determine optimal conditions for P. capillacea production in the Azores, and evaluates its vegetative growth in two experiments using von Stosch’s medium designed to test entire thallus and tips portions response to different irradiances (30, 70 and 150 μmol photons m-2 s-1). The best relative growth rate (RGR) was recorded at 150 μmol photons m−2 s−1 for the entire thalli and tips after two-weeks and three-weeks, respectively, indicating that an acclimation period is necessary to assure the growth of this alga under experimental conditions. Higher RGR was obtained at higher irradiance (3.98 ± 2.10% fm day-1), but overall, growth rates were low or negative. Epiphytes were a serious problem towards the end of the entire thallus experiments, where Feldmannia irregularis proliferate at all irradiances. Future cultivation approaches complemented with other relevant environmental factors (e.g. pH, photoperiod, salinity), are recommended.

Resprouting potential of rhizome fragments from invasive macrophyte reveals superior colonization ability of the diploid congener

Abstract Non-native aquatic Ludwigia species from a polyploid complex are among the world’s most problematic invasive plants. These emergent, floating-leaved species respond to disturbance through fragmentation of shoots and/or rhizomes, spreading rapidly by hydrochorous dispersal and posing challenges for invasive plant management. While recruitment of clonal aquatic plant species from shoot fragmentation is well documented, regeneration from rhizome bud banks, although common, often is overlooked. It is further unclear how interactions among ploidy and resource availability influence regeneration success of rhizome fragments. We conducted a full factorial experiment in aquatic mesocosms to compare trait responses of Ludwigia congeners differing in ploidy (diploid, decaploid) grown from clonal rhizome fragments under contrasting soil nutrient availability (low, high). Similar to previous work with shoot fragments, the diploid congener had a higher relative growth rate and produced more biomass than the decaploid during this establishment stage of growth. High growth rates and biomass production were associated with greater rhizome N and P and reduced investment in belowground structures. Comparing these results to previous shoot fragment studies with Ludwigia, rhizome fragments appear to have much greater growth potential, suggesting that management strategies should minimize disturbance to prevent fragmentation and dispersal of belowground structures. Furthermore, rapid response to newly colonizing diploid invaders will be essential to minimizing spread, and reductions in nutrient loads to aquatic environments may be more effective toward controlling establishment of the diploid congener than the decaploid.

Wood density, growth and mortality relationships of lianas on environmental gradients in fragmented forests of montane landscapes

AbstractAimA better understanding of plant communities can be achieved by incorporating data of traits and dynamics into surveys. Wood density is a good predictor for growth and mortality in trees, but to date, no studies of lianas include all three. We examine how liana communities respond to environmental gradients and forest fragmentation in terms of abundance, diversity, size structure, mortality, relative growth rate and wood density, and tested how the latter three are related to each other in liana species.LocationXishuangbanna, SW China.MethodsWe repeated a survey of lianas (stems &gt;0.5 cm diameter) in 47 plots, distributed in forest fragments of various size, on different bedrock (limestone or sandstone), over an elevational range and across different topographic elements (ridge, slope, valley). We gathered wood density data for 116 of 166 species, covering 90% of all surveyed stems. We also determined relative growth rate, mortality, stem diameter and basal area.ResultsAt the species level, liana mortality and relative growth rate were lower at higher wood density, and mortality was higher with greater relative growth rate. At the plot level, liana communities in valleys had high relative growth and mortality rates as well as high abundance and diversity. Forest on limestone hosted few species but more large‐stemmed liana individuals, and communities had higher wood density weighted by basal area. Liana abundance, relative growth rates and mortality were greater and average wood density lower towards fragment edges, but the explanatory power of these models was low.ConclusionHabitat was the major factor shaping liana communities, whereas fragmentation was not an important predictor in our study. Resource‐rich environments such as valleys harbour diverse liana communities with high mortality and relative growth rates. This pattern matches earlier studies on survival/growth trade‐offs among plant species. The relationship between growth rates, mortality and wood density in lianas follows the same trade‐offs as found in trees.

Photosynthesis, growth, and biomass allocation responses of two Inga species to contrasting light

Inga marginata and Inga subnuda are evergreen N-fixing tree species that are frequently found in the initial stages of forest regeneration. I. marginata has a wide geographic distribution, encompassing the Brazilian Atlantic Rainforest and dry forests of central Brazil, whereas I. subnuda is endemic to the Brazilian Atlantic Rainforest. We conducted this study to compare the physiological, growth, and biomass allocation responses of I. marginata and I. subnuda to contrasting light environments. Considering that I. marginata and I. subnuda have a similar position in the forest succession and different geographic distributions, we tested a hypothesis that these two congeneric species have similar photosynthetic and growth responses to light availability but different biomass allocation. The plants were grown under three light conditions (36, 15, and 6 mol photons m−2 day−1) for 105 days. Growth, biomass allocation, light–response curves, and leaf pigments were compared among the light conditions and between species by using two-way ANOVA. Our hypothesis was partially supported because the two species had similar photosynthetic responses to changes in light availability, but differences in growth and biomass allocation. The higher relative growth rate in mass of I. subnuda is associated with its higher allocation of biomass to light capture, as shown by the higher values of leaf mass fraction (LMF) and leaf area ratio (LAR). Conversely, the higher values of root mass fraction for I. marginata were in contrast to the higher values of LMF, LAR, and specific leaf area for I. subnuda; this indicates that I. marginata should be better adapted to environments where water could be a limiting factor, which is consistent with its wide geographic distribution.

Moving to Keep Fit: Feeding Behavior and Movement of Helicoverpa armigera (Lepidoptera: Noctuidae) on Artificial Diet With Different Protein: Carbohydrate Ratios.

Insect herbivores can modify their foraging behavior to obtain a balanced food intake, and they tend to move between food sources with different nutrient values. We investigated this movement in early instar larvae of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) using a putative optimal artificial diet (OP) and high protein (HP) and high carbohydrate (HC) artificial diets based on protein (p) and carbohydrate (c) ratios. Larvae were allowed to choose between the same kind of diet cubes (effectively no-choice), or diet cubes with different p: c ratios. In no-choice tests, we found that first instar larvae remained longest on OP diet and spent the least time on HC diet, while third instar larvae remained longest on HC diet and spent least time on OP diet. First instar larvae moved the most when provided with HC diet, while third instar larvae moved most when provided with OP diet. However, both stages moved the least when allowed to choose between diet cubes with different p: c ratios. The relative growth rate decreased when larvae increased their movement, but this influence was not evident when larvae fed on HC diet. Larvae that fed only on HC diet had the highest relative growth rate, followed by larvae with access to all diets simultaneously, indicating a behavior to mix nutrient intake. We relate these findings to behavior of this major pest species under field conditions.

تأثیر عمق الزراعة وحجم الحبة فی انبات وتمیز بادرات محصول الشعیر.(Hordeum vulgare L)

A pot experiment was carried out in the winter season of 2016/2017, to study the effect of depth of seeding (3,6 and 9 cm) and kernel size (small, intermediate and large on germination percent and vigor, seedling characteristics including seedling length, root length ,seedling fresh weight and growth stages of seedling represented by days to unfolding of first, second and third leaf, in addition to leaf area and relative growth rate in barley cultivar Rihan-3. The experiment was laid out as factorial in randomized complete block design of three replicates. The results indicated a significant superiority of the 3 cm depth, compared to the other depths, in initiation of germination and the characteristics of seedlings where it gave the least number of days to emergence (6.78days), highest germination percentage (77.8%), seedling length and fresh weight (6.67 cm and 1.611 g, respectively), highest germination vigor (844) and highest relative growth rate (1.504 g/ day).The results also showed that large-sized kernels gave the highest values for germination percent (78.9 %), least time for differentiation of first, second and third leaves, longer seedling shoot and root lengths (13.33, 7.67 and 5.56 cm, respectively), heaviest seedling fresh weight (1.756 g) and seedling growth vigor (1051) in addition to highest values for relative growth rate (1.776 g/ day) and leaf area (192.5 mm2). Results showed the highest values ​​with the use of the large size of the grains. Germinant %( 78.9) differentiation time 0f 1sd-2nd-3rd leaf ,relative growth rate (1.776 g /day) and seedling fresh weight(1.756g), and also length seedling and root (5.56, 7.67, 13.33 cm), and the leaf area (192.5 mm2).