scholarly journals Impact of the timing and duration of weed control on the establishment of a rubber tree plantation

2014 ◽  
Vol 86 (1) ◽  
pp. 495-504
Author(s):  
CAIO D. GUZZO ◽  
LEONARDO B. DE CARVALHO ◽  
PAULO R.F. GIANCOTTI ◽  
PEDRO L.C.A. ALVES ◽  
ELAINE C.P. GONÇALVES ◽  
...  

Rubber tree production is reduced by weeds that compete for environmental resources; therefore, the timing and duration of weed control influences weed interference. The objectives of this study were to evaluate the growth of rubber tree (Hevea brasiliensis) plants, to determine the critical period for weed control, and to evaluate the growth recovery of rubber trees that coexisted with weeds for different periods of time after planting. Two groups of treatments were established under field conditions in the first year of the investigation: one group contained crescent periods of weed infestation, while the other contained crescent periods of weed control, also including a weed-free check and a total weedy check. In the second year of the investigation, the weeds were totally controlled. Urochloa decumbens was the dominant weed (over 90% groundcover). Crop growth was greatly reduced due to the weed interference. Plant height decreased more rapidly than did any other characteristic. Plant height, leaf dry mass, and leaf area decreased by 99%, 97% and 96%, respectively, and were the most reduced characteristics. Plant height also recovered more rapidly than did any characteristic when the period of weed control was lengthened. However, stem dry mass increased by 750%, making it the most recovered characteristic. The critical period for weed control was between 4 and 9½ months after planting in the first year; however, the rubber trees showed an expressive growth recovery when the weeds were controlled throughout the second year.

2016 ◽  
Vol 34 (2) ◽  
pp. 291-298 ◽  
Author(s):  
A.A.P. SILVA ◽  
A.M. OLIVEIRA NETO ◽  
G. NAIARA ◽  
R.A.K. KARPINSKI ◽  
C.D.G. MACIEL

ABSTRACT Several factors can influence wheat crop yield, they include the interference imposed by weeds is one of the most important. The objective of this study was to evaluate the critical periods of weed interference in early wheat in the midwest of the state of Paraná, Brazil. The experiment was conducted in an experimental area located in Campo Mourão - PR, during the year 2013, using the BRS Pardela cultivar. The treatments consisted of periods of coexistence and weed control in wheat. Periods of coexistence and control were 0, 7, 14, 28, 35 and the whole cycle at days after crop emergence (DAE). Number of reproductive tillers per plant, spike length, number of spikelets per spike, plant height and wheat crop yield, were significantly affected by coexistence with prevailing infestation of Raphanus raphanistrum, therefore, a critical period of interference was determined at 16 to 24 DAE.


Weed Science ◽  
2014 ◽  
Vol 62 (4) ◽  
pp. 608-618 ◽  
Author(s):  
Martina Keller ◽  
Geoffroy Gantoli ◽  
Jens Möhring ◽  
Christoph Gutjahr ◽  
Roland Gerhards ◽  
...  

The effect of weed interference on corn yield and the critical period for weed control (CPWC) were determined in Germany and Benin. Treatments with weed control starting at different crop growth stages and continuously kept weed-free until harvest represented the “weed-infested interval.” Treatments that were kept weed-free from sowing until different crop growth stages represented the “weed-free interval.” Michaelis–Menten, Gompertz, logistic and log–logistic models were employed to model the weed interference on yield. Cross-validation revealed that the log–logistic model fitted the weed-infested interval data equally well as the logistic and slightly better than the Gompertz model fitted the weed-free interval. For Benin, economic calculations considered yield revenue and cost increase due to mechanical weeding operations. Weeding once at the ten-leaf stage of corn resulted already profitable in three out of four cases. One additional weeding operation may optimize and assure profit. Economic calculations for Germany determined a CPWC starting earlier than the four-leaf stage, challenging the decade-long propagated CPWC for corn. Differences between Germany and Benin are probably due to the higher yields and high costs in Germany. This study provides a straightforward method to implement economic data in the determination of the CPWC for chemical and nonchemical weed control strategies.


2015 ◽  
Vol 43 (2) ◽  
pp. 355-360 ◽  
Author(s):  
Dogan ISIK ◽  
Adem AKCA ◽  
Emine KAYA ALTOP ◽  
Nihat TURSUN ◽  
Husrev MENNAN

Accurate assessment of crop-weed control period is an essential part for planning an effective weed management for cropping systems. Field experiments were conducted during the seasonal growing periods of potato in 2012 and 2013 in Kayseri, Turkey to assess critical period for weed control (CPWC) in potato. A four parameter log-logistic model was used to assist in monitoring and analysing two sets of related, relative crop yield. Data was obtained during the periods of increased weed interference and as a comparison, during weed-free periods. In both years, the relative yield of potato decreased with a longer period of weed-interference whereas increased with increasing length of weed free period. In 2012, the CPWC ranged from 112 to 1014 GDD (Growing Degree Days) which corresponded to 8 to 66 days after crop emergence (DAE) and between 135-958 GDD (10 to 63 DAE) in the following year based on a 5% acceptable yield loss. Weed-free conditions needed to be established as early as the first week after crop emergence and maintained as late as ten weeks after crop emergence to avoid more than 5% yield loss in the potato. The results suggest that CPWC could well assist potato producers to significantly reduce the expense of their weed management programs as well as improving its efficacy.


2018 ◽  
Vol 36 (0) ◽  
Author(s):  
R.R. ZANDONÁ ◽  
D. AGOSTINETTO ◽  
B.M. SILVA ◽  
Q. RUCHEL ◽  
D.S. FRAGA

ABSTRACT: Weeds emergence times modify competition with crops. Thus, the hypothesis was that the increase in weed emergence flow decreases the period prior to interference (PPI) in soybeans and increases the critical period of interference prevention (CPIP). The objective was to determine the PPI and the CPIP of weeds in soybean crops as affected by the preferred time of weeds emergence flow. Three experiments were conducted in the field in a randomized block design with four replications. The treatments were arranged in a factorial design with factor A consisting of coexistence or weed control in soybeans and factor B for eight periods (0, 7, 14, 21, 28, 35, 42 and 135 days after crop emergence (DAE)). The numbers of emerged plants and weed dry mass by genus and crop productivity were evaluated. The weed interference in culture during all the crop cycle reduces the soybean average yield 73, 94 and 89% in the first, second and third sowing times, respectively. Chemical control may be adopted at the end of PPI, which must be done at 14, 15 and 5 DAE crop, for the first, second, third times, respectively. The sowing in advance and intermediate time of recommendation increase the PPI in about 10 days, favoring the weed management in soybean crops.


Weed Science ◽  
1992 ◽  
Vol 40 (3) ◽  
pp. 441-447 ◽  
Author(s):  
Michael R. Hall ◽  
Clarence J. Swanton ◽  
Glenn W. Anderson

Field studies were conducted in southern Ontario to determine the critical period of weed control in grain corn and the influence of weed interference on corn leaf area. The Gompertz and logistic equations were fitted to data representing increasing durations of weed control and weed interference, respectively. The beginning of the critical period varied from the 3- to 14-leaf stages of corn development However, the end of the critical period was less variable and ended on average at the 14-leaf stage. Weed interference reduced corn leaf area by reducing the expanded leaf area of each individual leaf and accelerating senescence of lower leaves. In addition, weed interference up to the 14-leaf stage of corn development impeded leaf expansion and emergence in 1989.


2016 ◽  
Vol 34 (4) ◽  
pp. 721-728 ◽  
Author(s):  
M. PADILHA ◽  
A.A.M. BARROSO ◽  
L.B. CARVALHO ◽  
F.R. COSTA ◽  
S. BIANCO

ABSTRACT The objective was to determine whether a change occurs in the critical period of weed interference prevention in narrow row corn with the use of atrazine and whether there is influence of the herbicide on crop yield components. The treatments consisted of periods without or with an initial weed control (0, 21, 35, 49, 63, 77, and 91 days after emergence), with or without application of atrazine in spikely post-emergence. The experiment was carried out in a 2 x 7 randomized blocks design (with and without weed control and seven periods with three replications). The use or not of atrazine was arranged in a split plot design. The most important weed species were Senecio brasiliensis, Urochloa plantaginea, Conyza bonariensis, Sida rhombifolia, and Solanum spp. Corn yield reduced by 15% and 18% with and without application of atrazine, respectively. The number of grains per spike and corn yield were negatively influenced by coexistence with weeds, while the number of rows per spike, the diameter and length of spike were not affected. Corn yield components were not affected by the use of atrazine. The critical period of weed interference prevention was 35 days without atrazine and 23 days with application of atrazine. There is a reduction of the critical period of weed interference prevention on narrow row corn by using atrazine, with no influence of the herbicide on crop yield.


Author(s):  
А.М. Мазин

В статье представлены результаты оценки сортов клевера лугового селекции Смоленской ГОСХОС по урожайности зеленой и сухой массы и хозяйственно-ценным признакам за 2019-2020 годы. Целью наших исследований являлось изучение восьми перспективных сортов клевера лугового для рекомендации их возделывания в условиях Псковской области и возможного использования в селекционной работе. Исследовательская работа с сортами клевера лугового проводилась в коллекционном питомнике на опытном поле лаборатории агротехнологий ОП Псковский НИИСХ, который был заложен в 2019 году. Высокий урожай зеленой массы и сухого вещества, в сумме за два года пользования, показали сорта: Надежный – 19,2 т/га (от стандарта +4,4 т/га), Тайлен – 18,9 т/га (+ 4,1 т/га), Смоленский 29 – 18,1 т/га (+3,3 т/га), Починковец – 16,9 т/га (+2,1 т/га) и Делец – 15,1 т/га (+1,5 т/га). Погодные условия вегетационного сезона в 2019 и 2020 годах были благоприятными для роста и развития клевера лугового. Укосная спелось – фаза начала цветения клевера, у раннеспелых сортов наступила в среднем на 9-17 дней раньше, чем у позднеспелых. Засорённость травостоев в первом укосе второго года пользования составила 5-7% и повышалась во втором укосе по некоторым сортам до 30% видового участия. В первый год жизни растений наибольшая облиственность была у раннеспелых клеверов и составляла от 43 до 48%. Во второй год жизни – год основного использования травостоев клевера, от укоса к укосу облиственность растений клевера повышалась. Самый высокий показатель дружности отрастания был отмечен у сортов Починковец, Смоленский 29, Делец и Стодолищенский. Для возделывания в условиях производства в Псковской области можно рекомендовать сорта Надежный, Тайлен, Смоленский 29, Починковец и Делец. The article presents the results of the evaluation of meadow clover varieties selected by the Smolensk state farm according to the yield of green and dry mass and economically valuable characteristics for 2019-2020. The purpose of our research is to study eight promising varieties of meadow clover to recommend their culti- 25 vation in the conditions of the Pskov region and possible use in breeding work. Research work with varieties of meadow clover was carried out in a collection nursery on the experimental field of the laboratory of agricultural technologies of the Pskov research institute, which was founded in 2019. The high yield of green mass and dry matter, in total for two years of use, was shown by the Reliable varieties – 19.2 t/ha (from the standard +4.4 t/ha), Tailen-18.9 t/ha (+ 4.1 t/ha), Smolensky 29 – 18.1 t/ha (+3.3 t/ha) and Delets – 15.1 t/ha (+1.5 t / ha). The weather conditions of the growing season in 2019 and 2020 were favorable for the growth and development of meadow clover. The mowing season is the phase of the beginning of clover flowering, in early-maturing varieties it occurred on average 9-17 days earlier than in late-maturing varieties. The weed infestation in the first mowing of the second year of use was 5-7% and increased in the second mowing for some varieties up to 30% of the species participation. In the first year of plant life, the highest leafiness was in early-maturing clovers and ranged from 43 to 48%. In the second year of life – the year of the main use of clover herbage, the leafiness of clover plants increased from mowing to mowing. The highest rate of amity of reg rowth was noted in the varieties Pochinkovets, Smolensky 29, Delets and Stodolishchevsky. For cultivation in production conditions in the Pskov region, we can recommend the varieties Reliable, Tailen, Smolensky 29, Delets and Pochinkovets.


2016 ◽  
Vol 46 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Sandro Cardoso ◽  
Edimilson Volpe ◽  
Manuel Claudio Motta Macedo

ABSTRACT Soil acidity and lack of nitrogen fertilization limit the yield of forage grasses. This study aimed at evaluating the effects of lime (0 kg ha-1; 2,000 kg ha-1; 4,000 kg ha-1; and 8,000 kg ha-1) and nitrogen (0 kg ha-1, 20 kg ha-1, 40 kg ha-1, 80 kg ha-1 and 160 kg ha-1) doses on forage accumulation, soil chemical properties and macronutrient concentrations in leaf blades of Massai grass (Panicum maximum cv. Massai). A randomized blocks design in a 4 x 5 factorial scheme, with four replications, was used. Lime and nitrogen doses positively affected the accumulation of green dry mass in the Massai grass as well as the base saturation in the soil. The maximum yield was obtained at nitrogen doses close to 587 kg ha-1 year-1 for nitrogen and 5,796 kg ha-1 for lime, which produced the greatest accumulation of green dry mass (15,267 kg ha-1 year-1) in the first year of assessment. The demand for lime increased from the first to the second year. Lime increased the base saturation, whereas nitrogen reduced it. The nitrogen applied to the soil raised the nitrogen, magnesium and calcium contents (g kg-1) in the leaf blades of Massai grass. Thus, Massai grass reacted positively to nitrogen and lime doses, with significant effects on the accumulation of green dry mass and soil characteristics assessed.


2013 ◽  
Vol 37 (4) ◽  
pp. 299-305
Author(s):  
Flávia Fernanda Simili ◽  
Maria Lúcia Pereira Lima ◽  
Maria Izabel Merino de Medeiros ◽  
Claudia Cristina Paro de Paz ◽  
Ana Claudia Ruggieri ◽  
...  

In central Brazil after soybean or other annual agricultural species is harvested, sorghum hybrids are planted in the fall in order to establish pastures for grazing animals. This study conducted for two consecutive years aimed at quantifying the contents of hydrocyanic acid in the leaves and determining plant height, forage dry matter yield and the leaf/stem ratio for sorghum hybrid 1P400 at different ages. Statistical analysis was performed by regression analysis based on plant age. Leaf HCN content decreased with plant growth, ranging from 205.0 and 230.3 mg HCN/100 g leaf DM at two weeks old to 5.9 and 6.1 mg HCN/100 g leaf DM at five weeks old in the first and second year, respectively. The average heights measured varied from 60 and 56 cm, in the 4th week, to 117 and 151 cm, in the 8th week, during the first and second experimental year, respectively. Forage mass increased linearly with age and displayed average of 1.411 and 1.637 kg DM/ha in the first year and, 2.905 and 3.640 kg DM/ha in the second year, during the 7th and 8th week, respectively. Leaf proportion decreased while stem increased linearly with plant age. The leaf/stem ratio decreased with plant growth, elongation and increasing stem weight. The sorghum hybrid should be grazed only after five weeks or when the plant height is above 80 cm, in order to avoid the risk of cyanide poisoning.


1999 ◽  
Vol 34 (2) ◽  
pp. 188-193 ◽  
Author(s):  
Francisco Bedmar ◽  
Pablo Manetti ◽  
Gloria Monterubbianesi

Field studies were conducted over 3 years in southeast Buenos Aires, Argentina, to determine the critical period of weed control in maize (Zea mays L.). The treatments consisted of two different periods of weed interference, a critical weed-free period, and a critical time of weed removal. The Gompertz and logistic equations were fitted to relative yields representing the critical weed-free and the critical time of weed removal, respectively. Accumulated thermal units were used to describe each period of weed-free or weed removal. The critical weed-free period and the critical time of weed removal ranged from 222 to 416 and 128 to 261 accumulated thermal units respectively, to prevent yield losses of 2.5%. Weed biomass proved to be inverse to the crop yield for all the years studied. When weeds competed with the crop from emergence, a large increase in weed biomass was achieved 10 days after crop emergence. However, few weed seedlings emerged and prospered after the 5-6 leaf maize stage (10-20 days after emergence).


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