Climate plays a key role in the food productivity providing requisite water supplies, reclaiming soil fertility and regulating the optimum environmental conditions for growth and development of various crops likewise wheat.

Efficient use of rain water for wheat crop in rain fed area

Any change in climatic parameters beyond the optimum limits at different phenological phases may cause serious impacts on the economic yield. There is evidence of climate change on global and regional scales in the form of warming, sea level rise and extreme weather events. Such changes have impacted many regions of the world and several economic sectors.

South Asia’s climate is already changing and impacts of climate change on water resources, food, health, biodiversity, forestry and socio-economic sectors can already be observed at many places and additional challenges are likely in the future (Field et al., 2014). The global mean temperature has already risen by 0.85°C from 1880 to 2012 (Hartmann et al 2013).

The amount of heat stored in the global oceans has amplified, and the global mean sea level has risen by 225 mm from 1880 to 2012 (Church et al., 2013). Annual average global atmospheric carbon dioxide concentrations reached 400 parts per million (ppm) in 2013 and concentrations of the other major greenhouse gasses responsible for global warming are at their highest levels for at least 800,000 years (Ciais et al., 2013).

The occurrence of extreme meteorological events like high temperatures and heavy precipitation is expected to increase as a result of global warming, raising concern over how future climate change will impact natural and human systems. The Global Climate Risk Index 2014 placed Pakistan on 12th rank due to impacts of weather-related lossevents (Sönke et al., 2013).

Time series of area weighted mean daily temperatures in Pakistan averaged over each year shows a sharp rise in temperature during the first decade of 21st century except the year 2005 (PMD, 2012). There is 0.6–1.0°C rise in mean temperature along the coastal areas of Pakistan since the early 1900s while 10–15% decline in rainfall in coastal areas and arid plains in the southern half of Pakistan below 30°N latitude (Farooq et al., 2004).

The summer and winter precipitation, over the last 40 years, has increased in northern half Pakistan mainly along the foot-hills of the Himalayas. Any change in local weather conditions due to climate change poses threats to the agricultural productivity. Major sources of climate change in Pakistan include sea level rise, glacial retreats, frequent and devastating floods, higher temperatures, increased frequency of heat waves and an increase in the occurrence of droughts.

These climate change risks generate sequential challenges for present and future management as well as policy making and have a direct impact on agriculture, water resources, urban-rural management, and the overall economy. Both irrigated and rain-fed agriculture is vulnerable to extreme weather events. Heavy monsoon rainfall has caused severe recurring floods in major rivers of Pakistan since 2010.

The rough monsoon season in 2012 produced flooding conditions killing over 650 people. Floods in 2010 were the worst for Pakistan causing nearly 3000 deaths and affected 20 million people (WMO-No.1119). The 2012 floods affected around 3 million people in Pakistan, damaged thousands of hectares of agricultural crops and claimed approximately 450 lives (Blunden and Arndt, 2012).

Impact of climate change on agriculture:

Agriculture is extremely vulnerable to climate change, especially in Pakistan, because of its geographical location with arid and semi-arid conditions (Janjua et al., 2010).

An increase in temperature could affect arid and semi-arid areas more compared to humid regions. Productivity is being affected in Pakistan by a number of climatic variables including rainfall patterns, rising temperature, and elevated CO2. In 1949-50, the agricultural sector contributed 53 % to Pakistan’s GDP, which dropped to 31 % during 1980-81, and to 21.4 % during 2012-13. The floods of 2010 affected 20 % of the land area and the overall production loss of sugar cane, paddy and cotton were estimated at 13.3 million tons. Two million ha of standing crops were either lost or damaged.

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Between 60 and 88 % of the farming, households reported losses of more than 50 % of their major crops, including rice, vegetables, cotton, sugar, and fodder (GOP, 2011). Agricultural growth suffered a serious setback during 2000-2001 as a result of prolonged drought. The major crops registered decreased growth of almost 10%, while an overall decrease in growth was 2.6 %. Professionals estimate that Pakistan incurs financial losses of $5.2 billion annually as a result of environmental deprivation (Ahmad et al., 2004).

Source of water in Pakistan and cropping system:

Water supply for agriculture in Pakistan depends not only on rainfall but also on the snow and glacier meltwater that flows through the rivers and replenishes groundwater. During winter, heavy snow deposits over the Himalaya, Karakoram and Hindukush (HKH) mountains accumulate as snowpack and glaciers that melt in the summer to sustain the river flows.

The summer monsoon brings about 60% share of the total annual precipitation concentrated over the southern slopes of HKH. There are two cropping seasons in Pakistan, Rabi, and Kharif, which match with the winter and summer precipitation phases, respectively. Rabi crops (wheat, barley, pulses) are normally grown from November to April and Kharif crops (rice, cotton, sugarcane) from June to October.

The sowing and harvesting practices have an overlap of 1-2 months for both the growing seasons. Wheat and rice are the two major food crops which are largely Issue 26 Bokhari, S. A. A., G. Rasul, A. C. Ruane, G. Hoogenboom, A. Ahmad 11 consumed as staple food and food security mainly revolve around both of them. Rice is the second source of food after wheat and accounts 2.7 percent in value added to agriculture (Government of Pakistan, 2013).

Previous studies have shown that both crops are sensitive to variations in climate (Kaur and Hundal, 2006; Mahmood et al., 2012; Attri and Rathore, 2003; WWF, 2010; Mathauwda et al., 2000). High temperatures may have a positive impact on agriculture in the mountain areas of Pakistan, like the lessening of growing period for the winter crops.

As warming is taking place, the summer season is extending and water is shrinking; providing room to multiple cropping cultures in mountainous regions. It also has a significant impact on reduction in frequency of frosty nights and their sequential occurrence. Due to low temperature, wheat in the high mountain areas cannot even reach to maturity and is harvested early to be used as fodder.

Mahmood et al. (2012) showed that an increase in rainfall by 5% and 15% during September-October could have a negative impact on rice productivity. However, a decrease in rainfall during the period is positively associated with rice yield. Planting wheat in rain-fed (barani) conditions is being practiced in many countries which are getting more yield than in ours due to adoption of better management practices.

Enhance water use efficiency by different practices in rain fed area:

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Wheat production in rain-fed region can be enhanced by adopting certain management practices that include infiltrating and conserving moisture into the soil, selecting suitable wheat cultivars, well-timed sowing by recommended method, judicious use of fertilizers, controlling pest sand weeds and proper harvesting of the crop.

Cultivation of the crop in rain-fed areas involves preservation of moisture, the crucial growth factor for crops, from rainfall. The moisture collected from the monsoon rains during July and August is infiltrated into the soil and preserved for growing wheat crop. The surface run off of water from excess rainfall can be preserved for future use by wheat plants.

There are different method which are following;

By tillage:

To achieve the objective, the soil is loosened by tillage up to a depth of more than 20cm using a chisel plough before the advent of rainy season to enhance water permeation capacity of the soil. Exercising soils with mould board plough in the barani areas should be avoided as it turns the land upside down bringing salts at the surface layer hampering wheat germination and growth.When the rains stop, the land is planked tightly to withhold maximum moisture. The moisture magnitude retained in the soil depends upon the extent of precipitation, temperature, degree of management and soil properties like depth, texture and organic matter status.

For instance, a rainfall of less that 20cm adds very little water to soil not satisfactory for completion of wheat growth while the areas receiving a rainfall more than 50cm can be successfully put under wheat crop. Rain-fed lands may be left unsown during the summer season to provide all moisture contents conserved in the soil for successful wheat production.

By mulching

Other techniques can also be employed to reduce moisture depletion from soil before and during the growing period. One such technique is the mulching of soil surface to avoid evaporation losses. Mulches can be natural including straw, leaves, farm residues, compost etc. Or artificial including plastic sheet, rock, gravel etc. Moreover, spray of 100mm solution of glycinebetaine during the vegetative stages enables wheat plants to withstand against water stress.

Variety selection

Variety selection is crucial in the case of rain-fed grown wheat. Drought resistant or tolerant wheat varieties can better survive deficient moisture conditions. Research institutes in the country have developed varieties that are well adapted to rain-fed conditions. These include GA-2002, Chakwal-97, Rawal-87,Kohistan-97, Inqlab-91, and Pasban-90.

Sowing time for wheat in rain-fed areas is of key importance. Early sowing during last week of October and first week of November allows seeds to imbibe more water for germination due to sufficient moisture in the seeding zone. Moreover, temperature of approximately 25æC during this period supports rapid germination for a vigorous crop stand.

Seed rate

Seed rate for rain-fed crop is variable depending upon the time of sowing. In case of late sowing, the seed rate is increased. For instance, the seed rate for sowing up to 15 November is 125kg per hectare (ha) while late sowing between 16 November and 15 December requires 150kg per ha. Germination percentage of the seed must be equal to or more than 90 per cent.

Soaking of seed

Seed is soaked in plain water for 10-12 hours so that it may suck moisture to support germination. Wheat grains produced in rain-fed areas are usually petite than normal due to limited moisture. Therefore, precaution must be taken while selecting seed.

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Seeds are graded to remove undersized and shriveled sized grains for proper and uniform germination. It is suggested that fields in rain-fed areas be sown using a drill without any preparatory tillage. Eventually the zero tillage drills are deemed better for wheat cultivation in rain-fed areas.

Weed control:

Although, tillage plays significant role in managing weeds, however, moisture conservation is more critical while weeds germinated before sowing can be controlled using a non-selective herbicide like gramaxone or round up at 3.0L per ha and 2.5L per ha respectively.

Fertilizers Application:

Fertilisers if managed properly contribute more or less 50 per cent to total production of a crop. Moreover fertilisers enhance the 1000-grain weight, protein contents, gluten quality and bread making quality of the wheat.

All fertilisers in rain-fed sown wheat are drilled along with seed and placed 5-8cm below the seed to maximize its utilization. Fertilizer rates must be decided on the basis soil analysis and the amount of rainfall. However the general recommendations suggested by the agriculture department are as follows:

Area Annual rainfall Nutrient

rainfall (mm)

                         elements (kg ha-1)

 

N

P

K

Low

350

57

57-60

Medium rainfall

350-500

85

57 60

High rainfall More than

 

500

115 85

60

Foliar application of nutrient

Foliar application of two to four per cent urea and KCL solution at 50, 70 and 85 days intervals after sowing is advantageous to improve dry matter accumulation and net assimilation rate in wheat. Moreover, spray of five per cent zinc sulphate 60 days after sowing activates certain enzymes, promotes plant growth and boosts flowering and seed setting

Weeds control:

Weeds rapidly drain the soil moisture, fertilizer and other growth substances so required to be controlled from the very beginning. Pre-emergence application of stomp 33EC (pendimethalin) at 2.5L per ha effectively control weeds in rain-fed sown wheat. On the other hand sanitary measures and other cultural practices help minimize weed flora.

Pest control:

Termites severely threaten the rain-fed cultivated wheat by attacking the plant roots usually in patches causing the yellowing of plants and death in some cases. Chlorpyrifos 30EC application before the last tilling of soil solves the termite problem effectively.

Diseases control:

Diseases like rusts, smuts, ear cockle and foot rot etc. can gravely diminish wheat output in barani parts. Pre- sowing seed treatment with fungicides like vitavax, carbendazine, benlate (each at 2g per kg of wheat seed) depresses the disease infestation. Rouging to eradicate infected plants prevents further dispersalofdiseases.

Harvesting:

Wheat crop matures little earlier in rain-fed areas than the irrigated ones. Grain hardening, turning of leaves to light yellow and drying of straw are the signs of maturity. Moisture status of wheat grains at maturation is 18-22 per cent which is reduced by drying to less than 12 per cent for safe storage.

 

https://www.technologytimes.pk/wp-content/uploads/2019/03/Efficient-use-of-rain-water-for-wheat-crop-in-rain-fed-area.jpghttps://www.technologytimes.pk/wp-content/uploads/2019/03/Efficient-use-of-rain-water-for-wheat-crop-in-rain-fed-area-150x69.jpgAhmad MahmoodArticlesarea,changing,Climate,condition,Crop,efficient,Fed,Pakistan,Rain,water,wheatClimate plays a key role in the food productivity providing requisite water supplies, reclaiming soil fertility and regulating the optimum environmental conditions for growth and development of various crops likewise wheat. Any change in climatic parameters beyond the optimum limits at different phenological phases may cause serious impacts on the...Pakistan's Only Newspaper on Science and Technology
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