scholarly journals The frequency of growing season frost in the subalpine environment (Medicine Bow Mountains, southeastern Wyoming), the interaction of leaf morphology and infrared radiational cooling and the effects of freezing on native vegetation

1995 ◽  
Author(s):  
D.N. Jordan
1999 ◽  
Vol 13 (2) ◽  
pp. 257-263 ◽  
Author(s):  
Hamed K. Abbas ◽  
Dan J. Pantone ◽  
Rex N. Paul

A new biotype of common cocklebur, called multiple-seeded cocklebur (MSC), was found in Bell County, TX, in 1994. MSC has up to 25 seeds per bur, usually producing up to nine seedlings, whereas normal common cocklebur (NCC) has two seeds per bur which usually produce only one seedling. MSC burs are large, round, covered with hairy spines or prickles, and flattened on one end, with each seed terminated by a beak. Leaf morphology differs among the biotypes, and stems of MSC are straighter and smoother than NCC. Apomixis occurred with MSC but not with NCC. Both biotypes have potential dormancy with germination occurring in the second growing season. MSC produces increased numbers of seedlings which increases the difficulty in controlling common cocklebur.


2019 ◽  
Vol 12 (02) ◽  
pp. 120-123 ◽  
Author(s):  
Gray Turnage ◽  
John D. Madsen ◽  
Ryan M. Wersal ◽  
John D. Byrd

AbstractFlowering rush (Butomus umbellatus L.) is an invasive aquatic and wetland plant capable of developing monotypic stands in emergent and submersed sites. This plant can rapidly outcompete native vegetation and impede human practices by reducing recreation (boating, fishing, and skiing) and disrupting agricultural use of water resources (irrigation canals). Mechanical removal practices occurring biweekly, monthly, bimonthly, and once per growing season were compared with chemical control with diquat applied sequentially at 0.19 ppmv ai for two consecutive months over 2 yr (2016 and 2017). Biweekly removal gave the most consistent control of B. umbellatus biomass and propagules. Diquat application along with monthly and bimonthly clippings gave varying degrees of B. umbellatus control. Clipping once per growing season did not control B. umbellatus when compared with reference plants, while clipping B. umbellatus every 2 wk (biweekly) controlled rush propagules most effectively. However, it is unlikely this method will be sufficient as a stand-alone control option due to the slow speed of harvester boats, the potential these boats have to spread B. umbellatus propagules to more sites, and the expense of mechanical operations. However, clipping could be used as part of an integrated strategy for B. umbellatus control.


Trees ◽  
2021 ◽  
Author(s):  
Paul Grünhofer ◽  
Lena Herzig ◽  
Lukas Schreiber

Abstract Key message We identified two poplar clones of the same species as highly comparable, yet clones of two further species of the same genus to be distinctly different regarding multiple morphological and ecophysiological traits. Abstract Leaf morphology, wax composition, and residual (cuticular) transpiration of four poplar clones (two clones of the hybrid species P. × canescens, P. trichocarpa, and P. euphratica) were monitored from the beginning to end of the growing season 2020. A pronounced epicuticular wax coverage was found only with P. euphratica. As the most prominent substance classes of cuticular wax primary alcohols, alkanes and esters were identified with P. × canescens and P. trichocarpa, whereas esters and alkanes were completely lacking in P. euphratica. Wax amounts were slightly decreasing during the season and significantly lower wax amounts were found for newly formed leaves in summer compared to leaves of the same age formed in spring. Residual (cuticular) transpiration was about five to tenfold lower for P. × canescens compared with the two other poplar species. Interestingly, with three of the four investigated species, newly formed leaves in summer had lower wax coverages and lower rates of residual (cuticular) transpiration compared to leaves of exactly the same age formed in spring. Our findings were especially surprising with P. euphratica, representing the only one of the four investigated poplar species naturally growing in very dry and hot climates in Central Asia. Instead of developing very low rates of residual (cuticular) transpiration, it seems to be of major advantage for P. euphratica to develop a pronounced epicuticular wax bloom efficiently reflecting light.


1994 ◽  
Vol 24 (8) ◽  
pp. 1704-1710 ◽  
Author(s):  
Don E. Riemenschneider ◽  
Bernard G. McMahon ◽  
Michael E. Ostry

We conducted a study to determine whether genotypic and phenotypic covariances among important traits differed between collections of black cottonwood (Populustrichocarpa Torn & Gray) from British Columbia and northern Idaho. We also determined how differences in estimated covariances could affect various multiple-trait clonal selection strategies. The experimental design consisted of 166 clones from British Columbia and northern Idaho intermixed at random in two replications of three-tree row plots. Measurements made during the second growing season included tree height, frequency and number of sylleptic branches, number of leaves, and the lengths and areas of leaf plastochron index 5, 10, and 15 leaves at the end of the growing season. The severity and extent of Melampsora leaf rust and Septoria leaf spot were also evaluated. We found high heritability for tree height, phenology, leaf morphology, and resistance to damaging agents. However, no advantage to using leaf morphology to improve genetic selection for tree height was demonstrable. Restricted selection indices had high potential utility for controlling increases in damaging agents. However, the relation between tree height and leaf diseases varied between the British Columbia and northern Idaho collections of black cottonwood, and between black cottonwood and an adjacent experimental population of balsam poplar (Populusbalsamifera L.). Such population-related variation in intertrait covariances suggests that selection strategies involving disease resistance may need to be evaluated on an individual population basis.


1992 ◽  
Author(s):  
Nicholas Wellington
Keyword(s):  

2020 ◽  
Vol 0 (6) ◽  
pp. 13-19
Author(s):  
Guzel Gumerova ◽  
Georgiy Gulyuk ◽  
Dmitry Kucher ◽  
Anatoly Shuravilin ◽  
Elena Piven

Data of long-term researches (2015–2018) in southern forest-steppe zone of the Republic of Bashkortostan, is justified theoretically and experimentally the mode of irrigation of potatoes on leached chernozems of unsatisfactory, satisfactory and good ameliorative condition of irrigated lands. For the growing periods of potatoes with different heat and moisture supply, the number of watering, the timing of their implementation, irrigation and irrigation norms are established. On lands with unsatisfactory meliorative state the number of irrigation depending on weather conditions of potato vegetation period varied from 0 to 3 (1.5 on average) with average irrigation norm – 990 m3/ha. With satisfactory meliorative state of lands the number of irrigation on average increased from 0 to 4 (2.3 on average) with irrigation norm – 1305 m3/ha. On lands with good meliorative state the number of irrigation was the highest – from 1 to 5 (3 on average) with average irrigation irrigation norm is 1653 m3/ha. It was noted that in the dry periods of potato vegetation the greatest number of watering was carried out (3–5 watering), and in the wet periods (2017) watering was not carried out except for the area with a good reclamation state, where only one irrigation was carried out by the norm of 550 m3/ha. Water consumption of potato was studied in dynamics as a whole during the growing season and the months of the growing season depending on weather conditions of vegetation period and land reclamation condition of irrigated lands, as well as in the control (without irrigation). The lowest total water consumption was in the area without irrigation and averaged 226.8 mm. In irrigated areas, its values increased to 319-353.4 mm. The average daily water consumption varied from 2.12 to 3.3 mm. The highest rates of potato water consumption were observed in June and July, and the lowest – in May and August. In the total water consumption of potatoes on the site without irrigation, the largest share was occupied by atmospheric precipitation and in addition to them the arrival of moisture from the soil. Irrigation water was used in irrigated areas along with precipitation, the share of which was 30.2–46.1 %.


Author(s):  
H. Lilienthal ◽  
A. Brauer ◽  
K. Betteridge ◽  
E. Schnug

Conversion of native vegetation into farmed grassland in the Lake Taupo catchment commenced in the late 1950s. The lake's iconic value is being threatened by the slow decline in lake water quality that has become apparent since the 1970s. Keywords: satellite remote sensing, nitrate leaching, land use change, livestock farming, land management


2017 ◽  
Vol 4 (3) ◽  
pp. 43-49
Author(s):  
M. Miroshnychenko ◽  
O. Siabruk

Aim. The comparison of the effect of hydrothermal conditions and various agricultural practices on the emission of CO 2 from chernozems in the Left-Bank Forest-Steppe of Ukraine. Methods. The dynamics of the intensity of carbon dioxide emissions from chernozem calcic (typical chernozem – in Ukrainian classifi cation) was studied during the growing season of 2011–2012. The observations were based on two fi eld experiments with various methods of soil till- age (6–7 years from the beginning of the experiment) and fertilization systems (21–22 years from the beginning of the experiment). Particularly, plowing at 20–22 cm, disking at 10–12 cm, cultivation at 6–8 cm and direct seeding using Great Plains drill were studied among the soil tillage methods. Mineral system (N 45 P 50 K 45 ), organic system (manure 8 t/ha) and combined organic-mineral system (manure 8 t/ha + N 45 P 50 K 45 ) were studied among fertilization systems. The intensity of CO 2 fl ux was determined using the non-stationary respiratory chambers by the alkaline absorption method, with averaging of the results during the day and the frequency of once a month. Results. During the warm period, the emission of carbon dioxide from the soil changes dynamically depending on temperature and humidity. The maximum of emission coincides with the periods of warm summer showers in June-July, the minimum values are characteristic for the late autumn period. The total emission losses of carbon in chernozems over the vegetation period ranged from 480 to 910 kg/ha and varied depending on the methods of tillage ± (4.0–6.0) % and fertilization systems ± (3.8–7.1) %. The changes in the intensity of CO 2 emission from the soil under different methods of soil tillage are associated with hydrothermal regime and the depth of crop residues location. The biggest difference is observed im- mediately after tillage, but in the spring period the differences are only 12–25 %, and after drying of the top layer of soil become even less. Direct seeding technology provides the greatest emission of CO 2 from chernozem, which is fa- cilitated by better water regime and more complete mineralization of plant residues on the soil surface. Annual losses of carbon are the least under disking of soil at 10–12 cm. The changes in the intensity of CO 2 emission from the soil under different fertilization systems are associated with the involvement of the additional organic matter from plant residues and manure to the microbiological decomposition. The greatest emission was observed under the organic- mineral fertilization system, which increased the loss of carbon by 7–8 % in comparison with the mineral system in the unfavorable hydrothermal year and by 11–15 % in the more favorable year. These differences are observed mainly during the fi rst half of the growing season when there is a clear tendency to increase the intensity of soil respiration. Conclusions. The hydrothermal conditions of the warm period of the year are decisive in the formation of the CO 2 emission fl ow from chernozems. Due to the improvement of agricultural practices, emissions might be reduced but not more that by 15 % of natural factor contribution.


1970 ◽  
pp. 13-17
Author(s):  
Saifuldeen A. Salim ◽  
Isam Kudhier Hamza ◽  
Laith Farhan Jar

The present study was conducted to find out the water requirements and most suitable irrigation frequencies for cowpea (Vigna unguiculata L.) var grown under drip irrigation. The treatments were based on the IW:CPE ratio at different empirical pan factors 0.6 , 0.8, 1.0, 1.,1.4 , and 1.6 Ef (where Ef = IW/CPE). It was observed that the irrigation interval was variable values decreased by increasing Ef value and with the progress of the growing season. The 1.2 and 1.0 IW: CPE treatments with approximately 4 days irrigation interval were achieved the best results. The total amount of applied water during Cowpea growing season was varied between 247.7 and 266.5mm with 254.8mm as a mean. Irrigation treatment with Ef1.2 was superior over the rest of other treatments in fresh seed yield (5.13 ton.hec.-1), crop water productivity (2.14 kg.m-3), biological yield (6.88 ton.hec.-1) , fresh pod yield (7.33 ton.hec.-1), weight of 100 seed (31.28gm), number of seed/pod (9.34) and netting percentage (37.1). The lowest values of the most parameters used in this study were obtained by Ef 0.6 irrigation treatment.  


Author(s):  
A.V. Konstantinovich ◽  
◽  
A.S. Kuracheva ◽  
E.D. Binkevich

In conditions of climate change, when temperature and precipitation fluctuations occur more and more frequently during the growing season, it is necessary to obtain high quality seedlings with "immunity" to various stress factors, including high weediness, the damage from which is associated with a decrease in yield (by 25 -35%) and with a deterioration in the quality of agricultural products. Due to the imbalance in production technology, seedlings are often weakened, overgrown, with a low yield per unit area and survival rate in the field. One of the solutions to this problem is the use of PP for pre-sowing seed treatment to increase the competitiveness of seedlings in the field.


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