Sorghum Halapense Research Articles

WEED FLORA IN ALFAFLA CROPS

Alfalfa is a perennial crop that is grown several years on the same surface and because of this there are specificities in the composition and structure of the weed community. This leads to difficulties in suppresses and reduction of pests, diseases and weeds at the yield of alfalfa. The basic harmful effect of weeds is reflected through the competitiveness of water, nutrients and light. Weeds generally have low nutritional value, unpleasant smell and taste, and also affect the quality of alfalfa seeds. The most common types of economy effective perennial weed are Cirsium arvense (L), Sorghum halapense (L.), Convolvulus arvensis (L.) and Cuscuta genus. All agro-technical measures, which enable good soil, quality sowing, as well as plant protection later, are the basic measures for the protection of alfalfa from long-lasting weed species. This paper is based on analysis of weeds flora in alfalfa crops in the Nis district. The presence of the fifteen most important types of weed plants was found in all nine analyzed areas of alfalfa crops. Among the weeds, most common are Agropyrum repens(L.), Amaranthus retroflexus(L.), Chenopodium hybridum(L.), Cuscuta sp.(L.), Sorghum halapense(L.).

Predicting weed invasion in Canada under climate change: Evaluating evolutionary potential

Clements, D. R. and DiTommaso, A. 2012. Predicting weed invasion in Canada under climate change: Evaluating evolutionary potential. Can. J. Plant Sci. 92: 1013–1020. Many weed species have already advanced northward from the United States into Canada, and their number threatens to increase with warming trends under climate change. For many weed species, this range expansion can be attributed to evolutionary adaptation by northern populations occurring in areas experiencing warmer climates and longer growing seasons in recent decades. In this paper, we examine the potential for invasive plant species to be selected for one or more of 10 character traits: (1) high growth rate, (2) wide climatic or environmental tolerance, (3) short generation time, (4) prolific or consistent reproduction, (5) small seed size, (6) effective dispersal, (7) uniparental reproduction capacity, (8) no specialized germination requirements, (9) high competitive ability, and (10) effective defenses against natural enemies. If any one of these traits is selected for in an invasive species, it would provide the affected species with the potential for a more expansive invasion range than anticipated by models that assume a static genotype. Four weed species of interest exhibiting potential northward range expansion within North America were evaluated: an obligatory outcrossing annual dicot, Himalayan balsam (Impatiens glandilifera Royle), a mostly selfing annual dicot, velvetleaf (Abutilon theophrasti Medic.), a perennial dicot that reproduces via rhizomes but forms fertile hybrids, Japanese knotweed [Fallopia japonica (Houtt.) Ronse Decr.], and a primarily selfing perennial grass, johnsongrass [Sorghum halapense (L.) Pers.]. Evidence for potential evolutionary responses to climate change was observed among particular traits for each of the four species, despite population genetic differences. The population genetics of invasive plants are difficult to model, as is climate change itself, but consideration of weed evolution to whatever degree possible should lead to improved predictive power of such models.

Characterization of a novel cellulose synthesis inhibitor.

The physiological effects of an experimental herbicide and cellulose synthesis inhibitor, N2-(1-ethyl-3-phenylpropyl)-6-(1-fluoro-1-methylethyl)-1,3,5-triazine-2,4-diamine, called AE F150944, are described. In the aminotriazine molecular class, AE F150944 is structurally distinct from other known cellulose synthesis inhibitors. It specifically inhibits crystalline cellulose synthesis in plants without affecting other processes that were tested. The effects of AE F150944 on dicotyledonous plants were tested on cultured mesophyll cells of Zinnia elegans L. cv. Envy, which can be selectively induced to expand via primary wall synthesis or to differentiate into tracheary elements via secondary wall synthesis. The IC50 values during primary and secondary wall synthesis in Z. elegans were 3.91 x 10(-8) M and 3.67 x 10(-9) M, respectively. The IC50 in suspension cultures of the monocot Sorghum halapense (L.) Pers., which were dividing and synthesizing primary walls, was 1.67 x 10(-10) M. At maximally inhibitory concentrations, 18-33% residual crystalline cellulose synthesis activity remained, with the most residual activity observed during primary wall synthesis in Z. elegans. Addition to Z. elegans cells of two other cellulose synthesis inhibitors, 1 microM 2,6-dichlorobenzonitrile and isoxaben, along with AE F150944 did not eliminate the residual cellulose synthesis, indicating little synergy between the three inhibitors. In differentiating tracheary elements, AE F150944 inhibited the deposition of detectable cellulose into patterned secondary wall thickenings, which was correlated with delocalization of lignin as described previously for 2, 6-dichlorobenzonitrile. Freeze-fracture electron microscopy showed that the plasma membrane below the patterned thickenings of AE F150944-treated tracheary elements was depleted of cellulose-synthase-containing rosettes, which appeared to be inserted intact into the plasma membrane followed by their rapid disaggregation. AE F150944 also inhibited cellulose-dependent growth in the rosette-containing alga, Spirogyra pratensis, but it did not inhibit cellulose synthesis in Acetobacter xylinum or Dictyostelium discoideum, both of which synthesize cellulose via linear terminal complexes. Therefore, AE F150944 may inhibit crystalline cellulose synthesis by destabilizing plasma membrane rosettes.

Phytogrowth-inhibitory activities of a clerodane from Viguiera tucumanensis

Abstract The phytotoxicity of clerod-14-ene-3α,4β,13ξ-triol, obtained from Viguiera tucumanensis (Hook. et Arn.) Griseb, was examined in Petri dish bioassays. This clerodane inhibited both germination and root growth of Sorghum halapense and Chenopodium album , and also slightly inhibited Ipomoea purpurea. Crop species also showed inhibitory activity: the growth and germination of Avena sativa was strongly inhibited. Germination of Brassica napus was unaffected. The strongest plant growth inhibitory activity of the clerodane was on C. album , and has been expressed as the p I 50.

Influence of increasing carbon dioxide concentration on the photosynthetic and growth stimulation of selected C4 crops and weeds

Plants of six weedy species (Amaranthus retroflexus, Echinochloa crus-galli, Panicum dichotomiflorum, Setaria faberi, Setaria viridis, Sorghum halapense) and 4 crop species (Amaranthus hypochondriacus, Saccharum officinarum, Sorghum bicolor and Zea mays) possessing the C4type of photosynthesis were grown at ambient (38 Pa) and elevated (69 Pa) carbon dioxide during early development (i.e. up to 60 days after sowing) to determine: (a) if plants possessing the C4photosynthetic pathway could respond photosynthetically or in biomass production to future increases in global carbon dioxide and (b) whether differences exist between weeds and crops in the degree of response. Based on observations in the response of photosynthesis (measured as A, CO2assimilation rate) to the growth CO2condition as well as to a range of internal CO2(Ci) concentrations, eight of ten C4species showed a significant increase in photosynthesis. The largest and smallest increases observed were for A. retroflexus (+30%) and Z. mays (+5%), respectively. Weed species (+19%) showed approximately twice the degree of photosynthetic stimulation as that of crop species (+10%) at the higher CO2concentration. Elevated carbon dioxide also resulted in significant increases in whole plant biomass for four C4weeds (A. retroflexus, E. crus-galli, P. dichotomiflorum, S. viridis) relative to the ambient CO2condition. Leaf water potentials for three selected species (A. retroflexus, A. hypochondriacus, Z. mays) indicated that differences in photosynthetic stimulation were not due solely to improved leaf water status. Data from this study indicate that C4plants may respond directly to increasing CO2concentration, and in the case of some C4weeds (e.g. A. retroflexus) may show photosynthetic increases similar to those published for C3species.

Comparison of the weedy vegetation in old-fields and crop fields on the same site reveals that fallowing crop fields does not result in seedbank buildup of agricultural weeds

Vegetation in 1 year old, 4 year old, 8 year old, and 8 year old fertilized fields were compared with weeds, in no-till and conventional till winter-rye summer-grain sorghum crop fields planted on the same site following the natural successional series. Crop stands were fertilized and treated with herbicide but at a minimum rate. Sørenson's indices of similarity were used to make the comparisons. Old field vegetation was quite different from the weedy growth in crop fields, quantitative similarity indices only 1–18%. The six major dominant species in old fields were not found at all in the crop fields, while the major crop weeds were found only sparingly in old-fields, with the exception of johnson grass ( Sorghum halapense). The no-till plot and the 8 year old fertilized field were the most similar (18%). It is concluded that species that become noxious agricultural weeds are those that adapt to fertilization and develop resistance to herbicides, and in general do not thrive in natural ecosystems. Accordingly, fallowing crop fields does not result in a seedbank buildup of species that will become weeds when crops are again planted on the land. If this finding proves to be general than a crop-fallow rotation practice will reduce weed problems and sustain soil quality over the long term.

Teliospore Maturation in the Smut Fungus Sporisorium sorghi: An Ultrastructural Study Using Freeze Substitution Fixation

Teliospores of the smut fungus Sporisorium sorghi developed in galls on Johnson grass (Sorghum halapense) inflorescences. Pieces of gall tissue were freeze substituted and processed for study with transmission electron microscopy. This procedure yielded well-preserved spores in different stages of development and permitted detailed ultrastructural observation of the spore maturation process. Uninucleate teliospore initials developed from sporogenous hyphae of S. sorghi. Hyphal walls appeared to gelatinize during the formation of spore initials, leaving the initials embedded in a fibrillar matrix. Young teliospores became surrounded by a primary wall as they enlarged. Large and small electron dense spines developed adjacent to the plasma membrane of the spore and grew into the primary wall. As spines developed, the primary wall partially disintegrated, with remnants persisting as a sheath around the spines. Two additional wall layers were then deposited beneath the spines. The outermost layer, with which the spines appeared to be continuous, was extremely electron dense and the thicker of the two layers. The inner layer was of moderate electron density. Each teliospore contained a prominent nucleus, mitochondria, microbodies, strands of rough endoplasmic reticulum, microtubules, and multivesicular bodies. Numerous lipid droplets were also present in each spore, many closely associated with microbodies.

Fecundity of Sugarcane Borer (Lepidoptera: Pyralidae), as Affected by Larval Development on Gramineous Host Plants

During a 2-yr study investigating the fecundity of the sugarcane borer, Diatraea saccharalis (F.), 607 pupae were collected on four gramineous hosts. Weight, length, and diameter of sugarcane borer pupae collected on corn, Zea mays L. cv. Merrit, and a sugarcane borer-susceptible sugarcane (a complex hybrid of Saccharum spp.) variety, CP 61-37, were greater (P < 0.05) than those of pupae collected on johnsongrass, Sorghum halapense (L.) Persoon. Female pupae collected on a moderately resistant sugarcane variety, CP 65-357, weighed significantly less (P < 0.05) and were shorter than those collected on CP 61-37 or corn. The sex ratio of sugarcane borer was independent of host plant. The best model for predicting sugarcane borer fecundity was that of a linear regression on pupal weight, with fecundity increasing at 4.3 eggs for each milligram increase in pupal weight, regardless of host or year from which the pupae were collected. Fecundity of moths collected from corn and the susceptible sugarcane variety was greater (P < 0.05) than that of moths collected from johnsongrass or the moderately resistant sugarcane variety. The potential finite daily rate of increase of sugarcane borer populations was determined to be 1.132 on corn and CP 61-37, 1.128 on CP 65-357, and 1.119 on johnsongrass.

Variation in kafirin and alcohol-soluble glutelin chromatograms of sorghum inbred lines revealed by reversed-phase high-performance liquid chromatography

Separations of kafirin and alcohol soluble glutelin proteins by reversed-phase high-performance liquid chromatography (RP-HPLC) from 7 inbreds and one hybrid of sorghum [Sorghum bicolor (L.) Moench] and one source of Johnsongrass [Sorghum halapense (L.) Pers.] were compared. Objectives were to assess the stability of protein profiles for seed sources produced at different locations and in different environments to examine the potential of RP-HPLC to provide genotypic profiles for sorghum. Analyses of variance data showed that levels of variation due to environments and locations were small; the majority of variation (93%) was among genotypes. Associations among inbreds revealed by multivariate and cluster analysis showed similarity with those that would be expected on the basis of pedigree. A chi-square analysis showed no deviation in the hybrid profile from the expected 2∶1 ratio of peaks from the female and male inbred parents, respectively. Improvements in the ability to correctly assign common peaks are necessary before associations among numerous sorghum genotypes can be reliably demonstrated by analysis of data from reversed-phase high-performance liquid chromatography (RP-HPLC).

Phytochrome Distribution in Johnsongrass Rhizomes

Phytochrome was assayed in vivo in the rhizomes of 12 to 14-week old johnsongrass [Sorghum halapense(L.) Pers.] plants. The phytochrome levels decreased basipetally from the apex through the eighth node. The decrease was logarithmic on a dry weight basis, but less rapid on a per segment basis. On a dry weight basis, higher phytochrome measurements were obtained with samples from the interior of the rhizome than from the external regions. The far-red absorbing form of phytochrome (Pfr) was shown to be very labile at 25 C in johnsongrass rhizomes. These results provide a basis for examining photomorphogenic responses of rhizomes to light and for correlating these responses to phytochrome photophysiology.

Pathogenesis and Host-Parasite Relations of the Cyst Nematode, Heterodera graminophila, on Grasses

A recently described cyst nematode, Heterodera graminophila, parasitized barnyard grass, Echinochloa colonum. Larvae penetrated roots and became oriented along the vascular cylinder in 12 days with sausage-shaped females developing within 18 days. The white, lemon-shaped cysts emerged through the epidermis leaving a crevice in the root at the infection site after the cyst was dislodged. A few eggs were left on the epidermis or in the crevice after 24 days, but most remained inside the cysts. Neither galling of host tissues, secretion of a gelatinous matrix around the eggs, nor giant cells around the feeding site were associated with H. graminophila. Necrosis of host-tissues was noticed in the pericycle and cortex, and a slight enlargement of the phloem occurred near the head of the nematode; no foliage symptoms were observed. Roots were generally parasitized by large numbers of nematodes at all stages of development. Secondary infection developed after 64 days; a few brown cysts were found at that time. Cell walls of the pericycle were thickened as evidenced by heavier stain. Males did not penetrate to the vascular area, but remained in the cortex near the epidermis where they molted and developed to maturity. Developing males fed only in the cortical parenchyma. Other host grasses were rice, Oryzae sativa, and Johnson grass, Sorghum halapense