Saturday, 15 July 2006
152-6

Management of Vertisols with Limited Water Availability for Improving the Productivity of Durum and Aestivum Wheats.

Uma Kant Behera1, Hira Nand Pandey2, and P. K. Varma2. (1) Indian Agricultural Research Institute, Pusa Campus, New Delhi, India, (2) IARI, Regional Station, Indore (Madhya Pradesh), India

In India Vertisol occupies an area of about 22.0 million ha. Most of these soils are confined to southern and central part of India. In central India, agriculture is largely wheat based occupying an area of about 7.1 million ha. Major cultivation of wheat in this region is either under rainfed or under limited (1-2) irrigations. On the other hand, over-exploitation of ground water for intensive agriculture, industry and domestic uses, is causing drastic decline in ground water level. Most of the water sources including tube wells and wells dries up in January and soils develops large cracks leading to quicker depletion of available soil moisture. The productivity of wheat in this region is quite low (1871 kg/ha). The low productivity is mainly due to the water stress of the crop at various growth stages. Hence, field experiments were conducted during rabi 1995-96 to 1999-2000 involving durum (Triticum durum Desf.) and aestivum (Triticum aestivum L.) wheat cultivars under varying irrigation levels and schedules based on growth stages under limited water availability situations. The soil of the experimental field was vertisols (fine, smectitic, hypothermic, Typic Haplusterts) with pH 7.8, organic carbon 0.5%, sand 13%, silt 34% and clay 53%. The soil water content of the top 60 cm soil measured by pressure plate is 32.5% by weight at 33 kpa and 17.5 % by weight at 1500 kpa. Experiment-1 : The treatments comprised five irrigation levels(four during 1998-99): I0 = Come up irrigation given immediate after sowing (CUI), I1 = CUI + CRI ( crown root initiation) , I2 = CUI + CRI+ FL( flowering), I3 = CUI +CRI+LJ (late jointing) + ML( milk), 14 = CUI + CRI+LT(late tillering) +LJ+FL+ML+D(dough) in the main plot and eight wheat varieties/cultivars of 4 durum and aestivum each in sub plots . The experiment was conducted in split plot design with three replications. Experiments-2: The treatments comprised five irrigation treatments: I0 = Come up irrigation(CUI) , I1 = CUI + CRI, I2 = CUI + LT, I3 = CUI + LJ, 14 = CUI + CRI + LJ in the main plot and 8 wheat varieties/ cultivars ( 4 durum and 4 aestivum cultivars including near iso-genic lines) in sub-plot with four replications. Early duration semi-dwarf aestivum varieties, viz. LOK-1 and GW 173 produced higher grain yield, compared to mid-late varieties, when one irrigation was applied at CRI stage. At one irrigation, semi-dwarf varieties yielded better than tall varieties, indicating that semi-dwarf varieties may perform better under limited (1 or 2 ) irrigations, compared to tall varieties. Durum performed better than aestivums, when more than one irrigations were applied at different growth stages. Rate of photosynthesis and transpiration increased with increasing levels of irrigations and leaf water potential showed positive correlation with grain yield. The study revealed that maximum grain yield of 5397 and 5960 kg/ha was obtained during 1998-99 and 1999-2000, respectively when six irrigations were applied at various physiological growth stages. Durum performed better than aestivum with an yield advantage of 4.5 to 8.1% at all levels of irrigations except come up irrigation and irrigation at CRI, where yield levels of aestivum and durum were at par. Under limited water availability situations as prevalent in central India, shifting of customary CRI irrigation to late tillering (LT) and late jointing (LJ) increased grain yield in all the cultivars. The maximum grain yield of 3350 kg/ha was obtained when one irrigation was applied at late jointing. Shifting of CRI irrigation to LT and LJ resulted an yield advantage of 12 % and 24 %, respectively. Application of two irrigations at CRI and LJ gave the maximum grain yield of 36.47 q/ha.. The performance of durum and aestivum wheat were similar under one irrigation at CRI/ LT/ LJ. However under two irrigations at CRI and LJ, durum cultivars exhibited superior performance over aestivum. The delay of irrigation from CRI to LT/LJ resulted in increase in effective tiller plant, 1000-grain weight, dry matter accumulation . 1000-grain weight and effective tillers were highest at I3 in all the cultivars and it was significantly higher than I2 in most of the cultivars. This indicates that irrigation application at late jointing may help in increasing the kernel weight. In the vertisols of central India with high water holding capacity and swell-shrink properties of soil durum cultivars produced higher grain yield than aestivum when more than one irrigations were applied based on physiological growth stages. Shifting or delaying the CRI irrigation to LT to LJ improved the productivity of wheat by 12.4% and 22.5%, respectively compared to irrigation applied at CRI. Rate of photosynthesis and transpiration increased with increasing levels of irrigations and leaf water potential showed positive correlation with grain yield.

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