Authors:
P. Ratnakumar
, P.S. Minhas, G.C. Wakchaure, R.L. Choudhary, P.P. Deokate |
Abstract:
Supplemental irrigation, drought tolerant cultivars and use of plant bioregulators are now being
proposed as the key strategy to unlock the yield potential and stabilize the yield of wheat grown
in rainfed areas. Experiments were therefore conducted during 2013-2015 using line source
sprinklers (LSS) to determine the interactive effects of quantities of supplemental irrigation and
exogenous foliar sprays of plant bioregulators- 10 mM thiourea (TU) and 32 ppm of ortho-silicic
acid (OSA) on wheat (Triticum aestivum L.) varieties viz., HD2189, LOK1, NIAW 301, NIAW
34 and PBW 550. The irrigation quantities were: fully irrigated (I1:31.8cm); mild (I2: 28.9cm);
medium (I3: 25.9cm and I4: 22.7cm); and severe (I5: 19.9cm and I6: 17.2cm) water stress
conditions. Wheat cultivars varied in their response to water deficits and those popular with
farmers e.g. NIAW-301 showed higher water productivity under deficit irrigation. Response to
TU, OSA also varied across water regimes and was higher under moderate to severe stress.
Foliar application of TU and OSA at root crown initiation, flag leaf and grain filling stages
improved yield by 6-9 % at fully irrigated; 18-19% at medium stress; 12-17% at severe water
stress conditions and water productivity by 0.12- 0.10 Mg h-1 with TU, 0.13-0.09 Mg h-1 with
OSA at fully irrigated and medium stress; 0.11-0.03 Mg h-1 with TU, 0.12-0.03 Mg h-1 with OSA
at severe stress conditions. TU and OSA induced efficient use of water through increased relative
water content, modulating canopy temperatures and enhanced total soluble sugars and sink
partition those are essential for enhanced water productivity under deficit irrigation. Our
interpretation is that varieties like NIAW 301, NIAW 34 and LOK1 with higher water
productivity under medium and severe water stress intensities, though having comparatively low
potential yields, should be preferred and exogenous application of PBR's like TU and OSA
could further enhance wheat productivity. |
