After rice, wheat is the most important cereal in India. It is grown
in cooler regions of India during the mild winter months of November to
mid-April. Nearly 26 million hectares (mio ha) are sown with wheat. Of this,
24.5 mio ha are sown with spring bread wheat or Triticum aestivum, nearly 1.5
mio ha go under durum (T. durum); Khapli or T. dicoccum covers less than 50,000
ha, and a few fields of T. monococcum have been reported from Rajasthan.
India's annual wheat production has been around 72 mio tons for the last few
years, with minor variations between years. This puts India in second position
among the wheat producing countries, with approx. 12 % of the world's wheat
production. But India is also the second largest wheat consumer after China,
with a quickly growing demand. The diverse growing environments are used to
produce wheat grain with different quality attributes, so India is able to meet
both domestic and international consumer needs.
1. India's Wheat Growing Zones
Wheat is the most important winter cereal grown during the non-monsoon
months, and it is less vulnerable to yield fluctuation than other crops. On the
contrary: production of the monsoon-season rice crop is dependent on good
rainfall distribution. In order to have a reliable and robust food security
system it is essential to have an adequate quantity of wheat.
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Fig. 28: Wheat growing zones. (The boundaries of India as shown in this
map are neither accurate nor authentic.)
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The wheat-growing parts of India differ considerably in respect of
soil type, temperature and moisture regime and are divided into six mega
environments (Fig. 28): Northern Hill Zone (NHZ), North West Plain Zone (NWPZ),
North East Plain Zone (NEPZ), Central Zone (CZ), Peninsular Zone (PZ) and
Southern Hill Zone (SHZ). The NHZ has approximately 1.2 mio ha under wheat,
which is grown at various elevations; on slopes it is un-irrigated, whereas
irrigation is feasible where rivers flow.
The NWPZ is the fertile, canal and tube irrigated (> 90%) tract of
the Gangetic plain, with alluvial soil and a very low gradient. Here, wheat
occupies more than 9.0 mio ha. For several days the minimum temperature remains
around 5 °C. In NWPZ wheat matures in 140 days, tillers well with more grains
per spike and therefore has a very high yield. The limitations are the
occurrence of karnal bunt (Tellesia indica) disease and grain shriveling due to
a sudden increase in the maximum temperatures around grain filling time.
The NEPZ has a network of rivers and drains, with high humidity, high
soil pH and irregular topography with unreliable irrigation services. The wheat
season is foggy for several days, and dew condensation on the leaves promotes
severe leaf blight (Dreschlera spp.) and brown rust (Puccinia triticiana).
Wheat matures here in 125 days and may be affected by pre-harvest summer
showers. The more than 9.0 mio ha under wheat in this zone falls into several
cropping sequences resulting from the irregular topology, the low-lying area
near rivers causes staggered wheat sowing.
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Fig. 29: "Tropicalized wheat". IARI variety HW 3070 is grown
in Tamil Nadu, close to the equator. Note coconut and wheat growing in the same
ecosystem.
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The CZ and PZ are predominantly highland areas with deep black soil,
and in these tracts wheat is grown over 5.0 mio ha and 1.0 mio ha,
respectively. Here wheat is cultivated under retreating soil moisture
conditions and at best, in some areas, farmers are able to provide two
irrigations. Wheat crops mature in 100 to 110 days and are continuously exposed
to high temperatures (Fig. 29). As a consequence there is poor tillering, and
the number of grains per spike is less, so per hectare productivity is only
around two tons. The low yields are compensated for by the high quality of the
grain. In the SHZ only a few hundred hectares are under wheat, and these hills
are the main source of inoculum against stem (P. graminis tritici) and leaf
rust (P. triticiana) for PZ and CZ. Hence, the development of rust-resistant
varieties is an important strategy for reducing crop loss in PZ and CZ.
2. Wheat Varieties
In the last forty years more than 200 wheat varieties have been
released for cultivation in the six mega wheat growing environments. Most of
the wheat varieties released for cultivation are for irrigated, high-fertility,
timelysown conditions or for the late-sown situation. Rain fed crop growth
conditions may account for 12% of the net area sown to wheat, and all Khapli is
grown as a rain fed crop. The seed replacement ratio in wheat is very poor and
mostly it is farmers' retained seed that is exchanged horizontally between
farmers.
Although breeders produce seed for more than sixty wheat varieties
each year, a maximum of fifteen varieties accounts for 80% of the crop, and of
these one or two cultivars cover 30% of the area.
Grain Quality
The physical aspects of grain quality include external features,
foreign matter presence, plant debris damage due to saprophytes, grain
diseases, stored grain pest damage and seed damage due to post-harvest
operations.
Physical Purity
The manual harvesting and threshing of wheat practised earlier used to
continue for two months after the harvest. But the situation changed
dramatically in the 1970 s, when farmers mechanized their operations with
tractor power. Following this, the local manufacture of threshing machines
started. Threshing and winnowing operations are now completed quickly by
mechanical means. In NWPZ nearly 60% of the wheat area is harvested by combines
on a custom hiring basis, whereas in the NEPZ and the PZ there is less use of
combines. The combine contractor roves over the wheat growing continuum of the
NWPZ and facilitates the harvesting process. The combine is generally not well
kept, and is only cleaned from time to time. It also carries a substantial
amount of seed from one field to another, thus promoting grain admixture. In
the combine-harvested fields there is a large percentage of broken grain
because of poor maintenance of the machine or over-drying of the standing crop.
Plant debris, weed seed and foreign matter are also abundant in
combine-harvested fields, and if the farmer does not fine-clean his harvest it
is difficult to market the produce.
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Fig. 30: Physical purity of freshly harvested wheat samples from
different states of India (data from AICWIP report, 2004).
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There are more shrunken and broken kernels in the freshly harvested
grain lots of Punjab, Haryana and the Plains of Uttaranchal, and to some extent
in Uttar Pradesh where combine harvesting is common practice. In states like
Uttar Pradesh, Haryana and the Plains of Uttaranchal many varieties are grown,
and the admixture of grains from different classes happens frequently. Foreign
matter content is very high in the grain harvest from Madhya Pradesh, and the
percentage of damaged kernels is distinctly high in the freshly harvested grain
samples from Punjab. In general the samples from NWPZ, which is the largest
grain surplus producing area, have low physical purity and fall into grade
II or III. Fig. 30 summarizes the physical purity of wheat samples from
different states in 2004.
Other Physical Features
Relevant to Milling
Physical characteristics such as hectoliter weight, thousand grain
weight, grain hardness and texture are important for the grain trade. The wheat
grain samples from Punjab have a hectolitre weight (HLW) of approximately 78
(kg/100 L), a thousand grain weight of about 37 g and a sedimentation value of
< 40. The low temperature during the initial plant growth stages promotes
the number of grains per spikelet. The accelerated ripening due to sudden
terminal heat often results in small grain of uneven seed size. There are
varietal differences in seed size and thousand grain weight, and the
large-seeded genotypes rarely produce more than 3 or 4 grains per spikelet. The
wheat kernel from NEPZ is generally large with more than 10% seed moisture, and
has a sedimentation value above 40. The grains from PZ and CZ are hard and
lustrous, with > 80 HLW and yield around 70% flour recovery.
Based on physical parameters and purity, Indian wheat has been grouped
into five different grades in accordance with the international grading system.
The durum wheat grain is generally large and hard with a higher hectoliter value.
The CZ grain samples of bread wheat often have > 10% durum grain as an
admixture. Millers do not like such material, since it impairs the quality of
the flour. Most of the fresh grain arrivals from the farm need a first round of
cleaning before they are graded, dried and sent to the silo for storage. This
cleaning causes a 2.3 to 24.0% loss, depending on the grain grade (Gupta et
al., 2002) and thus reduces the profit margin of the trader and the cultivator.
Micronutrient Status of the
Grain
The micronutrient level of the grain is important. If it is low, it becomes
necessary to supplement the flour with zinc, iron, etc. Such fortification raises
the cost of the product, and to some extent this issue of micronutrient
enrichment of the grain can be addressed through plant breeding. The
micronutrient content of Indian wheat varies considerably. For example, C 306,
C 591, K 68, UP 262 and WH 712 have higher Zn, Fe and Cu levels than the
recently most popular varieties such as HD 2329 and PBW 343 (Tab. 43). The
micronutrient content in the first group of varieties and their excellent
chapatti-making quality make them ideal grain types, and so they generally
fetch a premium price in the market. The well-funded global programme "Harvest Plus" of the CGIAR (Consultative
Group on International Agricultural Research) addresses the issue of
micronutrient enhancement. Many national programmes are also targeted towards
accumulating the micronutrient-enriching genes in high yielding wheat. The
information available indicates that it is possible to combine good
micronutrient levels with high yield as in the case of WH 712 and with a good
gluten score, sedimentation value and chapatti-making attributes (chapatti is
flat, non-fermented Indian bread).
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| Tab. 43: Micronutrient, sedimentation-value and HMW data for Indian wheat |
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