Significant Reduction In Plant Height Research Articles

The use of strip-seeding for management of two late-season invasive plants

The spread and persistence of weedy plants in rangelands highlight the need for refinement of existing management techniques and development of novel strategies to address invasions. Strip-seeding – the strategic seeding of a portion of an invaded area to reduce costs and enhance success – is an underutilized management approach that holds promise for reducing weed dominance in grassland habitats. A strip-seeding experiment was established in 2011 in a California grassland where portions (between 0-100%) of invaded plots were seeded with native grasses. In 2016, we assessed the height, above-ground biomass and flower production of two late-season invasive plants: field bindweed and prickly lettuce. We found significant reductions in plant height and flower production (for both target invasives), and biomass (for field bindweed) in many of the seeded strips compared to the unseeded strips. Smaller seed applications demonstrated similar or better utility for weed control compared to greater seed applications, suggesting that this approach can be effective while reducing labor and materials cost of typical restoration management approaches. We did not find evidence that seeded strips provided invasion resistance to unseeded strips. This is possibly due to the lag in native species dispersal and establishment into contiguous unseeded strips, and suggests that strip-seeding might not provide invasion resistance to unseeded strips on timescales that are relevant to managers. However, this work does suggest that strip-seeding native species that overlap in phenology with target invasives can reduce late-season weed dominance on rangelands.

Response of mass selection in maize (Zea mays L.)

This study was conducted to quantify the progress towards grain yield and agronomic traits in maize genotypes through mass selection. The original maize population and the population derived after five cycles of mass selection were planted for comparison at research field of National Maize Research Program, Rampur, Chitwan, Nepal during winter season of 2011-2012. The maize genotypes were Arun-1EV, Arun-4, Pool-17, P501SRCO × P502SRCO, BGBYPOP, Across9942 × Across9944, S99TLYQ-B, S99TLYQ-AB and S01SIWQ-3, respectively. The experiment was laid down in randomized complete block design with three replications. Each replication consisted of 180 rows; 20 rows of each genotypes. The results showed that there was significant reduction in plant height, ear height, tasseling days, silking days, disease severity however significant increment in grain yield. The results showed that phenotypic superiority of the selected population over the original population was obvious.

Identification of phosphorylation proteins in response to water deficit during wheat flag leaf and grain development

BackgroundWheat (Triticum aestivum L.) serves as important grain crop widely cultivated in the world, which is often suffered by drought stress in natural conditions. As one of the most important post translation modifications, protein phosphorylation widely participates in plant abiotic stress regulation. In this study, we performed the first comparative analysis of phosphorylated protein characterization in flag leaves and developing grains of elite Chinese bread wheat cultivar Zhongmai 175 under water deficit by combining with proteomic approach and Pro-Q Diamond gel staining.ResultsField experiment showed that water deficit caused significant reduction of plant height, tiller number, ear length and grain yield. 2-DE and Pro-Q Diamond gel staining analysis showed that 58 proteins were phosphorylated among 112 differentially accumulated proteins in response to water deficit, including 20 in the flag leaves and 38 in the developing grains. The phosphorylated proteins from flag leaves mainly involved in photosynthesis, carbohydrate and energy metabolism, while those from developing grains were closely related with detoxification and defense, protein, carbohydrate and energy metabolism. Particularly, water deficit resulted in significant downregulation of phosphorylated modification level in the flag leaves, which could affect photosynthesis and grain yield. However, some important phosphorylated proteins involved in stress defense, energy metabolism and starch biosynthesis were upregulated under water deficit, which could benefit drought tolerance, accelerate grain filling and shorten grain developing time.ConclusionsThe modification level of those identified proteins from flag leaves and grains had great changes when wheat was suffered from water deficit, indicating that phosphoproteins played a key role in response to drought stress. Our results provide new insights into the molecular mechanisms how phosphoproteins respond to drought stress and thus reduce production.

Transfer and Ecotoxicity of Titanium Dioxide Nanoparticles in Terrestrial and Aquatic Ecosystems: A Microcosm Study.

With the advancement in nanotechnology, particularly the use of TiO2 nanoparticles (NPs), there is a need to study their release into the environment and assess the related risk in an environmentally relevant contamination scenario. In the present study, the transfer and toxicity of TiO2 NPs in microcosms mimicking terrestrial and aquatic ecosystems were evaluated. The contaminated soil was prepared by spiking natural soils, with these then used as the basis for all exposure systems including preparation of soil leachates for amphibian exposure. Results demonstrated significant reductions in bacterial (-45%) and archaeal (-36%) nitrifier abundance; significant translocation of Ti to M. truncatula leaves (+422%); significant reductions in plant height (-17%), number of leaves (-29%), and aboveground biomass (-53%); nonsignificant Ti uptake in snail foot and viscera, and excretion in feces; and genotoxicity to X. laevis larvae (+119% micronuclei). Our study highlights a possible risk of engineered TiO2 NPs in the environment in terms of trophic transfer and toxicity in both terrestrial and aquatic environments.

Control of Maize Vegetative and Reproductive Development, Fertility, and rRNAs Silencing by HISTONE DEACETYLASE 108.

Histone deacetylases (HDACs) catalyze the removal of acetyl groups from acetylated histone tails that consequently interact more closely with DNA, leading to chromatin state refractory to transcription. Zea mays HDA108 belongs to the Rpd3/HDA1 HDAC family and is ubiquitously expressed during development. The newly isolated hda108/hda108 insertional mutant exhibited many developmental defects: significant reduction in plant height, alterations of shoot and leaf development, and alterations of inflorescence patterning and fertility. Western blot analyses and immunolocalization experiments revealed an evident increase in histone acetylation, accompanied by a marked reduction in H3K9 dimethylation, in mutant nuclei. The DNA methylation status, in the CHG sequence context, and the transcript level of ribosomal sequences were also affected in hda108 mutants, while enrichment in H3 and H4 acetylation characterizes both repetitive and nonrepetitive transcriptional up-regulated loci. RNA-Seq of both young leaf and anthers indicated that transcription factor expression is highly affected and that the pollen developmental program is disrupted in hda108 mutants. Crosses between hda108/hda108 and epiregulator mutants did not produce any double mutant progeny indicating possible genetic interactions of HDA108 with distinct epigenetic pathways. Our findings indicate that HDA108 is directly involved in regulation of maize development, fertility, and epigenetic regulation of genome activity.

Exogenous Salicylic acid Ameliorates the Adverse Effects of Salt Stress on Antioxidant System in Rosmarinus officinalis L.

S ALT stress is a main factor limiting plant growth and productivity. Salicylic acid (SA) has been shown to alleviate the adverse effects of different environmental stresses on plants. To investigate the protective role of salicylic acid (SA) in alleviating salt stress on Rosmarinus officinalis L. (rosemary) plant, a pot experiment was conducted to measure the growth parameters such as plant height and branch number. An antioxidant defense system, represented by catalase (CAT), superoxide dismutase (SOD) and peroxidase (POX), was evaluated at both biochemical and transcriptional levels. NaCl was applied at 0, 25, 50 and 100mM and 0, 0.2 and 0.4mM of SA were used. The exposure of rosemary plant to salt conditions resulted in significant reduction of plant height, branches number and increases in the three measured antioxidant enzyme activities, compared to control. The foliar application of SA effectively increased growth rates and enhanced the activities of CAT, SOD and POX enzymes. The PCR (RT-PCR) analysis revealed that the relative transcript levels of SOD, CAT, and POX genes were changed and up-regulated compared to the control due to NaCl stress and SA treatments, reached the highest expression level by applying 25mM NaCl and 0 SA treatments. The results implied that SA regulated the transcript levels of the antioxidant genes, resulting in the increased contents of antioxidant enzymes and enhanced salt tolerance.

Higher density planting benefits mechanical harvesting of rapeseed in the Yangtze River Basin of China

Winter rapeseed is an important oilseed crop in the Yangtze River Basin. To optimize its cultivation in this area and improve its production efficiency, a split-plot experiment with various planting dates (25 September and 10 October), nitrogen applications (120, 240 and 360 kg ha−1) and planting densities (3.0 × 105, 4.5 × 105 and 6.0 × 105 plants ha−1) was performed to investigate their effects and interactions on the seed yield of rapeseed, its lodging index and weed occurrence in farmland. Our results indicated that (1) Delay in planting led to the decrease in the net photosynthetic rate (Pn) of leaf, nitrogen seed production efficiency (NUE), pod number per plant and yield, but aggravated weed occurrence. The increase in nitrogen fertilization resulted in reduced NUE, elevated Pn of leaves, improved pod number per plant and yield, and facilitated weed growth. The increase of planting density elevated NUE, reduced Pn and yield per plant because of the lowered number of pods per plant, but enhanced the population yield and substantially inhibited weed growth. (2) Delayed planting inhibited rapeseed growth, showing significant reductions in plant height, rhizome diameter, root dry weight, aboveground dry weight and root/shoot ratio, and resulted in lower snapping resistance but a higher lodging index. Although higher nitrogen application improved root dry weight, rhizome diameter and snapping resistance, it resulted in the increase of plant height and aboveground dry weight, which led to a reduced root/shoot ratio and a greater lodging index. The increase in planting density lowered the rhizome diameter, root dry weight and snapping resistance, significantly reduced the plant height and aboveground dry weight, hence increasing the root/shoot ratio, which further decreased the lodging index. A linear relationship was observed between the seed oil content and lodging index (2013–2014, R2 = 0.3783**; 2014–2015, R2 = 0.5641**). Oil content was reduced while the lodging index increased, indicating that lodging index was a key factor determining oil content under various planting dates, nitrogen amounts, densities and their interactions.

English

Ethanol production from sweet sorghum depends on the quality of the biomass and sugars in the juice extracted from the plant. However, quality may be compromised by Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) or sugarcane borer infestation. This study evaluated the effects of infestation by the pest on sweet sorghum juice productivity and quality. Sorghum variety BRS506 was planted in an experimental area with 4,800 m2. Samples were harvested at 115 days after planting and the following variables were evaluated: physical injury caused by the pest in the stalk, juice yield, total soluble solids in the juice and chemical composition. Additionally, the presence of Fusarium sp. in the stalks was checked. A significant difference was detected for juice yield, with lower values found in bored stalks resulting in a 2.62% decrease in juice yield at an infestation intensity of 4.16%. Infestation of D. saccharalis also caused a reduction of 34% in the plant sucrose content and significantly decreased fiber, lignin and ash rates. Infestation by D. saccharalis in sweet sorghum caused a significant reduction of plant height, juice productivity, and was associated with the presence of Fusarium sp., and sugar and fiber reduction.   Key words: Chemical composition, integrated pest management, juice quality, sugarcane borer.

Generation of octoploid switchgrass in three cultivars by colchicine treatment

Polyploidization is regularly regarded as an important tool for the generation of innovative germplasm resources and plant breeding. In this study, autopolyploid switchgrass lines were produced from calli derived from immature inflorescence of tetraploid switchgrass (Panicum virgatum L.), both lowland cv. Alamo and Kanlow, and upland cv. Ranlow, through colchicine treatments. Ploidy levels of plantlets regenerated from the calli were screened by flow cytometry. Growth characteristics of the tetraploid and octoploid switchgrass cultivars were further investigated in a field experiment. Compared with the tetraploid plants of the three switchgrass cultivars, the corresponding octoploid plants showed significant reduction in plant height, number of tillers per plant and fresh matter, but an increase in leaf length and width.

Effect of Okra Yellow Vein Mosaic Virus (OYVMV) on Plant Growth and Yield

Okra yellow vein mosaic virus (OYVMV) is one of the most destructive diseases of okra plant. In the current study, effect of okra yellow vein mosaic virus (OYVMV) was assessed on plant growth and yield in naturally infected crop under agro-ecological conditions of Hyderabad district. The virus showed the significant reduction in plant height, number of leaves, flowers, fruits, and over all pickings and yield of all the locations wherever the crop was examined in the district. The significant reduction in plant height (48.67 cm) in infected plants as compared to healthy plants (62.96 cm) was recorded. Similarly, significant difference in the flowers formation per plant at all four locations was recorded in diseased (0.912) and healthy (2.165) plants. Fruit weight was also significantly reducing due to the disease prevalence at all four locations (73.25 g) as compared to healthy observed fruits (91.50 g). Interestingly, on overall basis there were more numbers of leaves (20.66) in infected plants as compared to healthy one (16.33). It is obvious from the results that virus (OYVMV) showed significant increase in number of leaves but reduced plant height, flowers, fruits and yield at all four observed locations, thus, pathologists and breeders are advised to work more on evaluation of resistant varieties using advanced molecular tools. The growers are also advised to adopt preventive as well as curative control measures so that the yield losses may be decreased.

Effect of growth retardants on growth and flowering of bougainvillea (Bougainvillea spectabilis) cv. Shubra

The present investigation to study the effect of growth regulators on growth and flowering of bougainvillea (Bougainvillea spectabilis) was carried out in the Division of Floriculture and Landscaping, IARI, New Delhi during 2012-13. The experiment was laid out in completely randomized block design with 11 treatments, 4 replications and 4 plants per replication. The bougainvilleas were planted in 10 inches pots in the month of July and were pruned back to a uniform height of 10+2 inches. The growth regulators, viz. maleic hydrazide, B-9 and paclobutrazol were applied in the form of foliar spray or drench and were compared with control (Distilled water) and the data were recorded for vegetative and flowering traits. Over a period of 14 weeks, it was observed that there was a significant reduction in plant height, plant spread, internode distance and shoot length with the application of maleic hydrazide followed by drenching with paclobutrazol. Maximum shoot diameter, maximum number of structural branches and maximum flower index was observed when plants were either sprayed or drenched with paclobutrazol.

Effect of Salinity Levels (NaCl) on Yield, Yield Components and Quality Content of Sesame (Sesamum Indicum L.) Cultivars

<p class="emsd-body"><span lang="EN-GB">Seeds of ten sesame cultivars (Karaj, Darab, Safiabad, Jiroft, Borazjan, Yellow-white, Felestin, Ultan, Isfahan and Abpakhsh) were sown into soil filled pots in 2008 and 2009. Pots were watered with six levels of salts (0.0038 (tap water as control), 4.89, 8.61, 10.5, 14.54, 17.74 ds.m<sup>-1</sup> NaCl) until full maturity. Plant height, root and shoot dry weight, yield and yield components, seed oil and protein contents of cultivars were measured. Increasing salinity caused significant reduction in plant height, root and shoot dry weight, yield and yield components, seed oil and protein contents of all cultivars. However, there were significant differences among the cultivars for measured traits for each salinity level. Based on seed oil yield data, Safiabad and Kraj at 0.0038ds.m<sup>-1</sup>, Safiabad and Ultan at 4.89ds.m<sup>-1</sup>, Ultan, Safiabad and Darab at 8.61 salinity levels were the superior cultivars. High variability in tolerance to salinity among the tested sesame cultivars suggests that selection of more salt tolerant cultivars for planting or breeding purposes is possible.</span></p><p class="emsd-body"><span lang="EN-GB">Highlights</span></p><p class="emsd-body"><span lang="EN-GB">Effects of contrasting salinity levels (0.0038 (tap water as control), 4.89, 8.61, 10.5, 14.54, 17.74 ds.m<sup>-1</sup>NaCl) on sesame cultivars were tested. Salinity reduced plant growth and yield and seed oil and protein contents. However, there were significant differences among the cultivars for measured traits for each salinity level. </span></p>

Evaluation of pea accessions and commercial cultivars for fusarium root rot resistance

Fusarium root rot caused by Fusarium solani f. sp. pisi (Fsp) can result in major yield losses in pea (Pisum sativum L.). Currently no fungicides effectively manage this disease. Previous studies evaluated the Pisum germplasm collection for resistance to Fsp, however, evaluations of commercial market classes of pea cultivars grown in the US, and elsewhere, have not been reported. This study evaluated pea accessions and commercial cultivars for Fsp resistance under greenhouse conditions. Accessions evaluated included pigmented lines with high levels of partial resistance to Fsp. Based on root disease severity (RDS) values, the most Fsp-resistant Austrian winter, green fresh, green dry, yellow dry, green winter and yellow winter pea were: PI 125673, 5003, ‘Banner’, ‘Carneval’, PS 05300234, and ‘Whistler’, respectively. Genotypes with a RDS value of 3.05, on a 0–6 scale with 6 being severe, or less had no significant (P ≤ 0.05) reductions in plant height, shoot dry weight, and root dry weight, compared to non-inoculated controls, establishing an important disease threshold value for pea breeders. Plant height, more than shoot dry weight or root dry weight, was the most highly negatively correlated growth parameter related to RDS in repeated tests based on Pearson’s Correlation coefficients. However, root dry weight was also a highly sensitive growth parameter affected by Fsp since 14 of 33 genotypes had significant (P ≤ 0.05) reductions in root dry weight compared to non-inoculated controls, while only 5 of 33 genotypes had significant reductions in plant height and/or shoot dry weight in combined tests.

Yield and yield traits of durum wheat (Triticum durum desf.) and bread wheat (Triticum aestivum L.) genotypes under drought stress

Field experiment was conducted to study the effect of water stress on yield and yield traits of durum wheat and bread wheat genotypes. Water stress caused significant reduction in plant height (PH), peduncle length (PL), spike number/m2(SN), spike length (SL), spike width (SW), spikelets number/spike (SNS), spike mass (SM), grain number/spike (GNS), grain mass/spike (GMS), biological yield (BY), thousand kernel mass (TKM), grain yield (GY) and harvest index (HI). Wheat traits such as SN, SM, BY, TKM, GY were more vulnerable to drought stress. Positive significant correlation of GY with SN, BY and HI under rain-fed condition was found. Genotypes of durum wheat were more sensitive to drought than that bread wheat genotypes. The significant and positive correlation of GY with Stress Tolerance Index (STI), Mean Productivity (MP) and Geometric Mean Productivity (GMP) indicated that these indices were more effective in identifying high yielding, drought tolerance genotypes.

Chickpea variety and phenology affect acquisition ofPea enation mosaic virus, subsequent plant injury and aphid vector performance

Acquisition of Pea enation mosaic virus (PEMV) by chickpea (Cicer arietinum) when fed on by viruliferous pea aphid (Acyrthosiphon pisum) was tested for combinations of two chickpea varieties (‘Bronic’, a kabuli type and ‘Sierra’, a desi type) and three plant ages (14, 28 and 42 days after germination). It was determined whether inoculation with PEMV influenced plant growth and yield components, and the effect of variety × age combinations on the survival and fecundity of aphid vectors was evaluated. Three important findings emerged: (a) Acquisition of PEMV by chickpea depended on plant age. When inoculated at 14 or 28 days, most plants tested positive for PEMV at harvest, while rates of virus acquisition were reduced for 42 day-old plants. (b) Plant age at inoculation affected growth and yield parameters, and this effect differed between chickpea varieties. For both varieties, PEMV infection reduced plant height and biomass at harvest when plants were inoculated at 14 days. Only ‘Sierra’ exhibited significant reductions in plant height and biomass when inoculated at 28 days. Seed set was severely diminished for both varieties when plants were inoculated at 14 and 28 days after germination, but mature plants were not damaged in terms of growth or seed set. (c) The performance of pea aphid was influenced by both chickpea age and variety, with higher fecundities and longer lifespan when colonising 42 day-old plants as compared with younger plants, and better performance overall on ‘Sierra’. This study reveals that chickpea can acquire PEMV at all ages tested, but the most damaging effects for growth and yield parameters occur when plants are inoculated at early phenological stages. Chickpea is a poor host for A. pisum in general, but plants can support vector populations long enough for PEMV transmission and subsequent yield reduction to occur.

Optimizing Sowing Methods Through Estimates of Interactions between Sowing Date and Genotypes in Some Morpho-Physiological Traits in Rice (Oryza sativa L)

For optimizing some morpho-physiological traits in two different sowing methods of boro rice genotypes at varying seeding time, a field experiment was carried out by IRRI at the research farm of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur; Bangladesh during 2010-12. A decreasing trend of plant height was observed at sowing dates after 8th December and the decreasing trend continued until January 07. The smaller plant in delayed seeding indicate the sensitivity of late seeding low temperature on the dry matter production of the genotype, unlike other genotypes which expressed no significant reduction in plant height due to late seeding. Significant responses of environments were found either in between the varieties but in between the sowing dates. Maximum number of effective tillers was observed in both direct seeded and transplanted condition in December 18. The tiller number increased with delayed seeding until December 18. But tillers numbers were found to decline afterwards. PSBRC82 took maximum days to flowering sowing at December 08th in transplanting condition but first flowering in direct seeding condition which is statistically different. And the earliest flowering was observed in BRRI dhan28 sowing at January 07. In direct seeding condition than in transplanting.OM2718 gave the maximum sterility when it was practiced in transplanting method than the direct seeded method at January 07. The increase of filled grains reflects clearly that the number of filled grains exhibited higher in direct seeded methods than transplanting method in all genotypes interaction with sowing date of December18th. Such difference in number of filled grains might be due to undisturbed root establishment in direct seeding method than transplanted Method. PSBRC82 sowing at December 18 resulted the highest grain yield in direct seeding methods followed by in BRRI dhan28 in transplanting.

Induction of dwarfing in bougainvillea cv Mahara by use of growth regulators

Bougainvillea (Bougainvillea spectabilis) is a very popular evergreen landscape plant in tropical and subtropical areas. Because of the vigorous growth habit, bougainvillea needs a lot of labor-intensive pruning when being used as a potted plant. PGRs could be alternatives to frequent pruning on bougainvillea to reduce labor costs. But, little research has been carried out on the use of plant growth retardants (PGRs) for controlling the growth and flowering. The present investigations were carried out to study the effect of growth regulators mainly; paclobutrazol, daminozide and maleic hydrazide on bougainvillea cv Mahara to induce dwarfing. The experiment was laid out in completely Randomized Block Design with 11 treatments and four replications. The rooted cuttings of bougainvillea were planted on 7 July 2012 in earthen pot (10” diameter) containing potting media consisting of sand: soil: FYM in a ratio of 1:2:1. The plants were pruned to a uniform height of 10+2 inches on 3rd September 2012. The growth regulators were applied in the form of foliar spray or drench and data was recorded for vegetative and flowering traits. After 14 weeks, it was observed that there was a significant reduction in plant height and plant spread when paclobutrazol was applied in the form of spray or drench. However, application of maleic hydrazide inhibited the plant growth, on the contrary increased plant height and plant spread over control (Distilled water spray) was observed with 5000 ppm Daminozide (B-9) application. Drench application of paclobutrazol @30 ppm resulted in highest flower index as compared to other treatments.

English

Effect of banana bunchy top virus (BBTV) on morpho-physiological characteristics of banana (Musa sp.) cv., Basrai plants was assessed. Healthy and BBTV infected samples of banana were collected from its open fields and micro-propagated aseptically. These plantlets were established in wire-house for three months. Presence of BBTV was confirmed by polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Micro-propagation efficiency of BBTV-infected plants was observed in less than healthy plants under in-vitro as well as in-vivo. Significant reduction in plant height, fresh weight (F wt) and dry weight (D wt) of leaf was observed in BBTV infected plants. A co-relation of peroxidase (POX) activity was observed with total carotenoids that increased in BBTV infected plants, while chlorophyll contents decreased significantly. Nitrate reductase activity also decreased with increase in proline contents in BBTV-stresses plants (p<0.05). Meanwhile, reducing sugars also increased but not-significantly. Bunchy top virus infection in banana therefore resulted in alteration of growth related physiological traits that led to retardation of plant growth.   Key words: Ex-vitro, Musa sp., micro-propagation, photosynthetic pigments, BBTV, peroxidases, total proteins, reducing sugars, cell size.

Plant response to touch affects the behaviour of aphids and ladybirds

Touching between leaves of the same plant and/or by neighbouring plants is one of the most common mechanical stimuli to which an individual plant has to respond on a daily basis. The possible ecological implications of a plant’s response to touch on plant–insect interactions have not been explicitly investigated. We examined whether plant response to 1 min daily touching over a period of 6 days affects host plant acceptance by the bird cherry-oat aphid Rhopalosiphum padi L. on maize and by the black bean aphid Aphis fabae Scop. on bean, as well as olfactory preference of an aphid predator, seven-spotted ladybird Coccinella septempunctata L. Maize plants responded to touch with significant reduction in plant height, total plant biomass, leaf weight, leaf surface, shoot/root ratio and specific leaf area (SLA), while bean plants responded with reduced stem height and reduced SLA. Both aphid species showed significantly reduced acceptance of touched plants compared with untouched plants. The two aphid species and male and female ladybirds preferred volatiles from untouched plants over those from touched plants. Volatiles in the headspace of touched and untouched plants were collected and identified. Stepwise discriminant analyses identified (E)-nerolidol and (E)-β-caryophyllene in maize and 6-methyl-5-hepten-2-one and an unidentified sesquiterpene in bean as the best discriminating compounds in the volatile profiles of touched plants. Our study suggests that touch-induced changes in plants can potentially affect host plant selection by aphids and habitat searching by ladybirds. Thus, touch-induced changes in plants may have significant effects at higher trophic levels.

The effect of field dodder (Cuscuta campestris Yunck.) on morphological and fluorescence parameters of giant ragweed (Ambrosia trifida L.)

The effect of the parasitic flowering plant known as field dodder (Cuscuta campestris Yunck.) on morphological and fluorescence parameters of infested giant ragweed (Ambrosia trifida L.) plants was examined under controlled conditions. The parameters of chlorophyll fluorescence (Fo, Fv/Fm, ?PSII, Fv, Fm, ETR and IF) were measured on infested (I) and non-infested (N) A. trifida plants over a period of seven days, beginning with the day of infestation. Morphological parameters (plant height, dry and fresh weight) were measured on the last day of fluorescence measurements. C. campestris was found to affect the height, fresh and dry weight of the infested A. trifida plants, causing significant reduction in plant height and dry weight. Field dodder also affected several parameters of chlorophyll fluorescence (Fo, Fv/Fm, ?PSII and Fv) in infested A. trifida plants.