Agriculture Reference
In-Depth Information
increases drought tolerance in plants. (xii) It controls certain soil-borne diseases. (xiii) It helps in the
formation of glycosides that give characteristic odors and flavors to onion, garlic, and mustard. (xiv)
It is necessary for the formation of vitamins and the synthesis of some hormones and glutathione.
(xv) It is involved in oxidation-reduction reactions. (xvi) It improves the tolerance to heavy metal
toxicity in plants. (xvii) It is a component of sulfur-containing sulfolipids. (xviii) Organic sulfates
may serve to enhance the water solubility of organic compounds, which may be important in deal-
ing with salinity stress (Clarkson and Hanson, 1980). (xix) Fertilization with soil applied S in sulfate
form decreases fungal diseases in many crops (Klikocka et al., 2005; Haneklaus et al., 2007).
Since S has many important functions in the plant, improvement in its uptake is important to
achieve maximum economic yields. Nitrogen fertilization has positive interactions in crop plants
(Zhao et al., 1997). Nitrogen has a strong influence on S assimilation and vice versa (Fageria and
Gheyi, 1999). Increasing N levels along with S improves crop yields quadratically (Fageria et al.,
2011a). Jackson (2000) reported that canola's ( Brassica napus L.) response to N fertilization reached
a plateau at about 200 kg N ha −1 without S addition. However, canola responds almost linearly to N
fertilization up to 250 kg N ha −1 when 22 kg S ha −1 was added.
When there is S deficiency in the soil, the growth of most crop plants reduces significantly. While
N directly affects the photosynthesis efficiency of plants, S affects the photosynthesis efficiency
indirectly by improving the NUE of plants, as evident from the relationship between N content
and photosynthesis rate in the leaves with S and without S-treated Brassica plants (Ahmad and
Abdin, 2000). In without S plants, photosynthesis was related to leaf N content only up to 1.5 g m −2 ,
whereas the relationship was linear even beyond 1.5 g m −2 in S-treated plants. Rapeseed plants
grown on S-limiting soils suppress the development of reproductive growth and could even lead to
poor seed set (Nuttall et al., 1987) or pod absorption (Fismes et al., 2000).
Oilseeds and legumes require a large amount of S compared to cereals and grasses (Aulakh and
Chhibba, 1992). Malhi and Gill (2002) reported that the application of N in association with S improved
grain yield, oil content, and S uptake in canola compared to no fertilizer and N-alone treatments sig-
nificantly. These authors also reported that NUE was 2.0 kg seed kg −1 N when N fertilizer was applied
alone and it increased more than five times (10.2 kg seed kg −1 N) when both N and S fertilizers were
applied. Mcgrath and Zhao (1996) reported an increase of 42-267% in the seed yield of Brassica
napus with the application of 40 kg S ha −1 along with 180 and 230 kg N ha −1 . Without S application,
the seed yield declined drastically due to S deficiency when the N fertilization rate increased from 180
to 230 kg N ha −1 . Such severe negative impacts when N alone was applied to S-deficient soils on seed
yield, oil content and production, protein content, and NUE in rapeseed and mustard crops have been
reported in several other studies from Canada (Janzen and Bettany, 1984; Nuttall et al., 1987), India
(Abdin et al., 2003), and Europe (Fismes et al., 2000; Walker and Booth, 2003).
Several field experiments with pulses such as chickpea ( Cicer arietinum L.), lentil ( Lens culi-
naris Medik), mungbean ( Vigna radiata ), black gram ( Vigna mungo ), pigeon pea ( Cajanus cajan
L. Millsp.), and cowpea ( Vigna unguiculata L. Walp) showed a significant increase in grain yield
due to balanced N, P, and S fertilization (Aulakh and Malhi, 2005). A synergistic interaction of
N × S has been reported by Tandon (1992) in several crop species in relation to yield, protein con-
tent, and nutrient uptake. The positive interaction of N × S in grain yield and seed oil content has
been reported by Aulakh et al. (1990). The yield of wheat, grown in the coastal plain of Virginia,
increased linearly with N + S application (Reneau et al., 1986). In four different studies in India, the
application of S with N and P produced an additional yield of 700-1300 kg and 400 kg ha −1 of wheat
and corn, respectively (Aulakh and Chhibba, 1992). Dev et al. (1979) reported a significant N × S
interaction in corn resulting in higher S uptake in the leaves and stems with increasing levels of N
and S in the growth medium. Mixing urea with elemental S in a 4:1 ratio prior to its surface applica-
tion onto a calcareous soil enhanced the NUE of pearl millets from 15% to 48% while reducing the
NH 3 volatilization by about 50% (Aggarwal et al., 1987). Sexton et al. (1998) reported that N and S
affect the level and composition of seed storage proteins in soybean. Kim et al. (1999) reported that
SO 4 2− and NO 3 are related to protein synthesis during N and S assimilation.
Search WWH ::




Custom Search