Issue-30 Vol. 1, Jan.-Mar. 2025 Paper ID-E30/9 ISSN:2581-7884 RNI:UPBIL/2017/75141
ABSTRACT
India is the
fourth largest oilseed producing country in the world. India contributes 30.01
M tons of oilseed production of world’s oilseed production 250 million tons per
annum. In India oilseeds are grown in an area of 26.44 M ha with annual
productivity of 1135 kg/ha. In India nine oilseed crops are grown in rabi and
kharif classified as edible (Soybean, Groundnut, Sesame, Rapeseed and Mustard,
Sunflower, Safflower, Niger) and non-edible (Linseed, Castor). In oilseed
production weed infestation is a major reducing factor. In field infestation of
weeds reduce productivity, increase production costs, poison stock and threaten
biodiversity and native plant communities. Weeds compete for nutrients, water,
solar radiation, space, CO2 etc. with crop plants. Weeds also act as
alternate hosts to several pests and pathogens e.g. in Castor Crotolaria sp
acts as an alternate host for Hairy caterpillar. However, the magnitude of competition depends
upon weed type, time of emergence, duration of infestation, crop seed quality
and genotype. Globally, it is estimated that food grain losses due weeds is 287 tones which accounts for 11.5
per cent of the total food production.
For mitigating the emerging problem of weeds in oilseed crops and by
keeping in mind long term safety of natural resources, environment, maintaining
or enhancing soil fertility there is need of a sustainable approach of weed
management. In sustainable approach weeds are managed in such a way which
enables soil health maintained, environment protection and effective
utilization of natural and physical resources and weeds are considered as part
of the biodiversity of the farm. So management is the general philosophy rather
than eradication. To ensure good crop growth and development it is essential to
reduce crop weed competition during initial period of crop weed competition as
given in table.
Weeds of Oilseeds
Annual: Acrachne
racemosa, Dactyloctenium
aegypticum, Digera arvensis, Echinochloa
spp, Elusine indica, Setaria gluca,
Sorhum sp, etc.
Perennial: Cirsium
arvense, Convolvulus arvensis, Cyperus spp., Cynodon dactylon,
Parthenium hesterophorus etc.
Parasitic: Orabanche
spp (in rapeseed-mustard and Niger), Cuscuta spp (in linseed).
Pre-Sowing Operations
The operations which are carried out before sowing of crops to prevent the
introduction of weeds from external sources in the crop field such as crop
rotation, cover crops, tillage systems, seed bed preparations, soil
solarisation, management of drainage and irrigation systems, crop
residue management, use of well decomposed FYM, use of good quality seed free
from weed seed (certified seed), clean the agricultural implement before and
after use in field etc. However its success depends on the biology,
reproduction and dissemination behavior of weeds and how a measure is adopted
to prevent the spread weeds.
Crop Rotation and cover crops
Crop rotation is highly effective non monitory inputs against parasitic weeds for example Orobanche ramosa in Brassicas, Cuscuta epilinum in linseed, Cuscuta campestris in niger etc. (Parker and Riches, 1993) and crop- associated weeds such as Cleome viscosa and Spergula arvensis in mustard and Phyllanthus niruri, Ageratum conyzoides in groundnut. The growth pattern of crop, weed control techniques, cultural practices, varies in rotation which creates a barrier for further proliferation of crop associated weeds. Cover crops, live mulches are used as inter crops to suppress weeds. Usually legume crops are the best choice for live mulch which suppress weeds as well as reduces weed seed bank in soil (Akobundu, 1987). Trap and catch crops are used for controlling parasitic weeds like Orobanche but not for Cuscuta.
which suppress weeds as well as reduces
weed seed bank in soil (Akobundu, 1987). Trap and catch crops are used for controlling parasitic
weeds like Orobanche but not for Cuscuta.
TABLE 1: Critical period of crop-weed
competition, yield losses and time of weeding Oilseeds
Crops Critical
Period Reduction in 1st weeding 2nd Weeding
(DAS) grain yield (%) (DAS) (DAS)
Soybean 20-45 40-60 20 40-45
Groundnut 30-45 40-50 20-25 40-45(hand pulling)
Rapeseed-mustard 15-40 15-30 25-30 _
Sesame 15-45 15-40 20-25 40-50
Sunflower 30-45 30-50 25-30 45-60
Safflower 15-45 35-60 20 40
Castor 30-60 30-35 30-35 60
Linseed 20-45 30-40 20-25 40-45
Niger 30-45 60-65 20 -
Crop Rotation and cover crops
Crop rotation is highly effective non monitory inputs against parasitic
weeds for example Orobanche ramosa in Brassicas, Cuscuta
epilinum in linseed, Cuscuta campestris in niger etc. (Parker and
Riches, 1993) and crop- associated weeds such as Cleome viscosa and Spergula
arvensis in mustard and Phyllanthus niruri, Ageratum conyzoides in
groundnut. The growth pattern of crop, weed control techniques, cultural
practices, varies in rotation which creates a barrier for further proliferation
of crop associated weeds. Cover crops, live mulches are used as inter crops to
suppress weeds. Usually legume crops are
the best choice for live mulch which suppress weeds as well as reduces weed
seed bank in soil (Akobundu, 1987). Trap and catch crops are used for
controlling parasitic weeds like Orobanche but not for Cuscuta.
Tillage Systems and seed bed prepration
Manipulation of soil with tools and implements creates conditions in favour crop growth and reduce initial flushes of weeds by destroying weed seed bank in soil. Frequent tillage encourages effectiveness of weed control against annual weeds more,wher
Soil Solarization
Soil solarization exploits solar heating to kill
weed seeds and therefore reduce weed emergence. It raises the soil temperatures
to the lethal level at which weeds are unable to complete the photosynthesis
and ultimately weed seeds and seedlings dies. Soil temperature rise 8-120C
and may reach around 500C.
The soil surface must be smooth and must contain enough water to favor
heat transfer down the profile and to make reproductive structure of weeds more
sensitive to heat damage to increase the solarization effect.
A plastic mulch film is laid down onto the soil to avoid heat dissipation
to the atmosphere.
Cultural Methods
Cultural practices that
aid in sustainable weed management include proper fertilization, good seed bed
preparation, use of high quality seed and so on. Use of good cultural practices
results in more vigorous crop growth that will compete more successfully with
the weeds.
Choice of crop species and crop variety
Select the oilseed crop having initial vigorous growth, competitive or smoother crop. Rapeseed and mustard is a good example of vigorously growing crop (faster canopy build-up, profuse branching, taller stature), highly competitive against weeds (Das T. K., 2008). Sunflower is good crop for rotational purpose and used as trap crop against Striga and stimulates its germination. In groundnut Virginia spreading type varieties (K 71-1 which weed growth about 50%) are more effective in weed control than Spanish bunch type genotypes (J 11, TMV 2).
Sowing time and method
Timely sowing of most of the oilseed
crops is reported as effective in weed control. Late sowing of Niger reduces
weed infestation. Soybeans can better use the weed control advantages of late
planting and narrow row spacing and are less affected by early stand losses
from mechanical weed control. Reducing row spacing would reduce the amount of
time required for the crop to “canopy over " and weed dry matter
especially in soybean and groundnut by increasing LAI and utilizing more
sunlight and thus reduces late season weed emergence and subsequent
competition. Row planting maintains required plant population with uniform
plant distribution and facilitates adoption of mechanical weed control
measures.
Seed Rate and Plant Population
Increased weed suppression with higher seed rates is results in increased LAI and light interception of the canopy, thus crop compete more effectively with weeds. In safflower, there is remarkable adjusting capacity to plant density. In addition, higher planting rates can compensate for crop losses that occur during mechanical weed control operations.
Cropping System
Intercropping involves spatial diversification of cropping systems, e.g., growing a smother crop (legumes) between rows of the main oilseed crop. It maintains ecological balance, more utilization of resources and reduces weed population. In suitable inter cropping or mixed cropping is found more remunerative weed control like maize + soybean, Rapeseed and mustard + wheat/barley/chickpea. In inter cropping system optimum plant population; spacing and planting time of main and inter crop, fertilizer schedule and initial weed control measure are to be considered.
Balanced Fertilization
Use of fertilizers in adequate and balance proportion is to be proved more beneficial for crop growth and development. Placement of fertilizers close to the root zones of crop encourage better uptake of nutrients by crops and less available to weeds. In sunflower pre-sowing application of synthetic N fertilizer increased the suppression of late-emerging weeds like Chenopodium album, Solanum nigrum and Xanthium strumarium compared to split application.
Mechanical methods
In India, mostly weeds are controlled either manually or mechanically in oilseed crops. Mechawidely to control weeds in the inter row spaces of a line sown crop. In groundnut nical weed control strategies were selective enough for oilseed crops if they were used in appropriate conditions.ditions. Hand pulling of individual weeds is most vital and effective method of weed management against annual and tap rooted weeds which reduce weed reproduction and seed dispersal. Hand hoeing is adopted
Hand pulling of individual weeds is most vital and effective method of
weed management against annual and tap rooted weeds which reduce weed
reproduction and seed dispersal. Hand hoeing is adopted widely to control weeds
in the inter row spaces of a line sown crop. In groundnut manually operated
implement star weeder and push hoe are more economical. Blade harrowing, in
relatively dry and loose soil within inter row spacing of groundnut is also
done to cuts the root system and weed die owing to desiccation. Hand weeding is
commonly used practices for weed control in oilseed crops either by spade, hand
hoe, or ‘khurpi’. In oilseeds 1-2 hand weeding are found beneficial for
controlling most of weed flora. It provide weed free environment during initial
period of crop growth. The time of weeding in different oilseed crops are given
in above table.
Supplemental herbicide use at minimum
possible rate
Use of various types of
herbicides is hazardous for human and soil health. Herbicides also cause
environmental damage such as water pollution and decline the population of
pollinators and beneficial insects in some oilseed crops such as rapeseed and
mustard, sunflower etc. In sustainable approach soil health is more critical
component which can be maintained by minimal or no use of herbicides.
Allelopaathy
Many plant species
like sunflower, Brassica spp produces chemicals that affect the
development of plants growing in their immediate environment. This is the
effective method of non-chemical weed control in ecological sustainable weed
management. Allelochemical are extracted from leaves, root, soils collected
from and around sunflower crop of sunflower which inhibit the seed germination
and seedling growth of many weed species (Wilson and Rice, 1968). The use of
rye, cut and left, prior to sowing soybean has been used widely in other
countries against weeds.
Conclusion
The concept of
sustainable weed management in oilseeds has increased in popularity over the
last few years. Sustainable approach is the profitable, ecofriendly, economic
and safe for effective utilization of natural resources. Holistic planning
provides farmers with the management tools they need to manage biological
complex farming systems in a profitable manner. There is an emerging consensus
that modern petrochemical-based farming is unsustainable and there is a need to
develop and promote ecological approaches to food production. Many plant
species have been reported to possess pesticidal and weed growth inhibiting
properties, but their potential remains untapped still.
References
1-Akobundu, I. O. 1987. Weed Science in the Tropics : Principles and Practices. John Wiley and Sons, New York, 522 pp.
2-Anonymous (2011-12) - Directorate of Economics and Statistics, Department of Agriculture and Cooperation, Ministry of Agriculture, Government of India.
3-Das, T. K. And Yaduraju, N. T. 2002. Compairing several crop husbandry practices with soil solarization for weed control and crop yield in soybean (Glycine max) – broccoli (Brassica oleracea convar botrytis var italica) cropping system. Indian Journal of Agricultural Sciences, 71(4): 284-286.
4-Das, T. K., 2008. Weed Science: Basics and Applications. Indian Agriculture Research Institute, New Delhi-110012.
5-Parker, C. and Riches, C. R. 1993. Parasitic Weeds of the World: Biology and Control. CAB International. Wallingford, UK.
6-Prasad R., 2004. Textbook of Field Crops Production. Directorate of Information and Publication of Agriculture, ICAR, Krishi Anusandhan Bhavan, Pusa New Delhi 110012, pp 372-621.
7-Reddy S R, 2011. Principles of Agronomy. Kalyani Publishers. pp 521-543.
8-Wilson R E and Rice E L, 1968. Allelopathy as expressed by Helianthus annus L. And its role in old-field succession. Bulletin of Torrey. Botanical club 85: 432-48.
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