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ELONGATION RATES OF ROOT AND SHOOT OF WHEAT DURING EMERGENCE AS AFFECTED BY MECHANICAL IMPEDANCE AND MATRIC POTENTIAL OF THE GROWTH MEDIUM

Sat, 20 Jan 2001 00:00:00 GMT

Title: ELONGATION RATES OF ROOT AND SHOOT OF WHEAT DURING EMERGENCE AS AFFECTED BY MECHANICAL IMPEDANCE AND MATRIC POTENTIAL OF THE GROWTH MEDIUM Authors: Nabi.G; C. E. Mullins Abstract: A laboratory study was conducted on a sandy loam soil to determine the effect of soil matric potential and soil mechanical impedance on wheat growth during emergence. Experiment was conducted in growth cabinet in which an unimpeded treatment was compared against an impeded treatment at three matric potentials, i.e. -10, -100 and 500 IcPa. The soil was packed in 300 mm long cylinders at dry bulk density of 0.88 Mg m'3 and 1.25 Mg m'3 . Five mm long seedlings of wheat variety Inqtab, were grown as a test plant. The results indicated that mechanical impedance and matric potential of the root medium significantly (P<0.05) affected fresh and dry root weights. The weights were reduced with decreased soil matric potential and increased soil mechanical impedance. In unimpeded treatment, about double the amount of fresh weight and dry weights of shoot were recorded than in impeded treatment at -10 and -100 kPa matric potential. The highest dry shoot weight of 23.5 mg was recorded when grown at -10 kPa in unimpeded soil. It was almost 2 times higher than that of impeded treatment. Root and shoot elongation in unimpeded treatments were reduced by 37 and 29 percent respectively at -100 kPa and II and 58 percent at -500 kPa matric potential. Similarly these reductions were of 64 percent in root length in impeded soil at -100 and -500 kPa. In unimpeded treatments, the roots at the three matric potential were almost 2 times longer than those of the impeded treatments. While shoots were 4 and 6 times longer at -10 and -100 kPa matric potential respectively. The results highlight serious consequences of soil compaction and matric potential on wheat growth in soil particularly during early growth stage.

RECLAMATION RESPONSE OF TWO DIFFERENT TEXTURED SALINE-SODIC SOILS TO EC|W TO SAR[W RATIOS

Sat, 20 Jan 2001 00:00:00 GMT

Title: RECLAMATION RESPONSE OF TWO DIFFERENT TEXTURED SALINE-SODIC SOILS TO EC|W TO SAR[W RATIOS Authors: Ghafoor.A; S. M. Nadeem; Anwar-ul-Hassan; M. Sadiq Abstract: A Lysimeter experiment was conducted to evaluate the effect of different ratios of electrical conductivity (ECiw) to sodium adsorption ratio (SARiw) of irrigation water to reclaim different textured saline-sodic soils. The ECllr:SARlw ratios were 4:1, 2:1, 1:1, 1:2 and 1:4 at EC1H, of 6 or 12 dS m''. The total water applied was equal to 3 pore volume in three equal splits. The results indicated that at both the ECiw, teachate volume increased with an increase in EC^SAR^. The EC and SAR of leachate remained statistically higher where ECilr:SAR,w ratios of the leaching solutions were lower than 1:1. The ECr ,pHs and SAR decreased with alt the treatments, decrease being statistically more with ECiw;SARi, ratio up to 1:1 or higher and was lower for loamy clay than that for the clay loam soil. The saturated hydraulic conductivity (K,„J decreased with a decrease in EClw:SARitl and vice versa and was statistically higher for clay loam than that for the loamy clay soil. It is concluded that better EClw:SARtw ratios were up to 1:1 for reclaiming clay loam and loamy clay soils at both the EC,„ levels of 6 and 12 dS m~'.

ZINC REQUIREMENT OF POTATO CROP IN THE PUNJAB

Sat, 20 Jan 2001 00:00:00 GMT

Title: ZINC REQUIREMENT OF POTATO CROP IN THE PUNJAB Authors: Chaudhary.R.A; M. Akram; K. H. GILL; M. A. Qazi Abstract: Fertilizer zinc (Zn) requirement of potato crop was assessed through ten fertilizer experiments conducted on farmers' fields in Lahore and Gujranwala divisions during 1996-97 to 1999-2000. The levels of Zn put to test were 0, 2.5, 5.0, 7.5, 10.0, 12.5 and 15.0 kg Zn ha'1. The data revealed that potato responded quadratically to the applied Zn, and 7.5 kg Zn ha'1 appeared to be the optimum dose for optimizing potato yield. Application of Zn at planting was found to be the best time of its application

EFFECT OF SALINITY X HYPOXIA ON SOME PHYSIOLOGICAL PARAMETERS OF TWO WHEAT CULTIVARS

Sat, 20 Jan 2001 00:00:00 GMT

Title: EFFECT OF SALINITY X HYPOXIA ON SOME PHYSIOLOGICAL PARAMETERS OF TWO WHEAT CULTIVARS Authors: Nawaz.S; M. Aslam; Z. Ahmad; R. H. Qureshi Abstract: Salinity and waterlogging are serious threats to the agriculture of Pakistan. Wheat being an upland crop is affected to a great level by waterlogging particularly when coupled with salinity. A hydroponic culture study was conducted to compare two wheat cultivars (Blue Silver and 7-Cerros) for their physiological characters under saline and hypoxic conditions. C01 assimilation rate decreased with the imposition of salinity and hypoxia and their combination. Blue Silver showed more C02 assimilation rate than 7- Cerros under stress conditions. Transpiration rate decreased with hypoxia indicating less availability of water but salinity showed no response and cultivars also showed similar response under alt treatments. Stomatal conductance decreased with the imposition of either hypoxia or salinity and Blue Silver had higher stomatal conductance, than 7- Cerros. Concentration of CO, in the sub-stomatal cavity decreased with salinity but hypoxia did not cause any chang