N. A. Sajedi & M. R. Ardakani & F. Rejali &F. Mohabbati & Mohammad Miransari 演講 : 朱偉健 老師 : 藍清隆 日期 : 2013/12/24

 Drought is one of the most important abiotic stresses affecting plant growth and yield →Damage to cell membrane and photosynthetic system →Decreasing leaf surface area →Reducing plant growth and production (ex. Photosynthesis↓, Nitrate activities↓ Hydrolyzing enzymes↓ )

 Under moderate to medium drought stress → Corn cellular development ↓  Corn can be planted using minimum level of irrigation water.  Nonetheless, under such conditions corn yield and some of its qualitative characters may be adversely affected.

 Arbuscular Mycorrhizal (AM) fungi → Alleviating the unfavorable effects of drought on plant growth. → Uptake of water and nutrients by the plant roots↑ by symbiotic relationship → Enhancer of plant: –Soil hydraulic conductivity ↑ –Transpiration ratio ↑ –Stomatal resistance ↓ by adjusting plant hormonal balance

 A type of mycorrhiza in which the fungus penetrates the cortical cells of the roots of a vascular plant  Arbuscular mycorrhizas(AMs): → Unique structures formation, arbuscules and vesicles by fungi of the phylum Glomeromycota  AM fungi and a variety of plants produces colonies on the exterior part of root system  Help plants to capture nutrients from the soil (ex. P, S, N and micronutrients)

 Zn → Activator for some enzymes: – Dehydrogenase – Super oxide dismutase (SOD) – Carbonic anhydrase – RNA polymerase, – Isomerase – Transphorylase – DNA polymerase → Regulates auxin (indole acetic acid) → Detrimental effects on male organogenesis and anthesis, and consequently decreases crop yield

 Zn → The interaction effects: –Between P and Zn → Alleviating effects: –Between Zn and antioxidant enzymes activities In this experiment, the effect of Zn was also tested to evaluate how the combined effects of Zn and AM fungi can influence the effects of drought stress on corn growth.

The objectives of this experiment: 1)To determine the effects of drought stress on corn growth and yield 2)To test the hypothesis that the combined effects of AM fungi and Zn can improve the alleviating effects of AM fungi on corn growth and yield under drought stress

 Before sowing → Soil samples collecting: 0–30 & 30–60-cm depths → Testing of physical and chemical properties –Soil texture (by Hydrometry method ) –pH of a saturated paste –Organic carbon (by Wet oxidation method) –Available phosphorus (bySodium bicarbonate extraction method) –Potassium (by Flame photometer method, Emission spectrophotometry) –Iron and Manganese (by DTPA method, Atomic absorption spectrometer)

 Start sowing → 3 levels of irrigations: – 100%(control), 75%, 50% – Requirement during to evaporation basin on a daily basis → 3 levels of Zn sulfate – 0, 25, 45 (kg/ha) – strip, 5cm underneath and beside the seeds

 Start sowing → 2 levels of AM fungi – Glomus intraradices –inoculated with the powder containing mycorrhizal propagules to seeds

 Corn → Hybrid corn → Late maturity → Single cob hybrid, with the American parents of B73 & MO17, which have come to Iran from former Yugoslavia in → Growth stage is between 130 to 140 days. → 6000 to 9000 kg ha−1. The mature plant → Relatively tolerant to drought stress & fungal diseases

 AM only → X  AM + Zn → O  AM effectiveness is dependent on the level of drought stress and Zn concentration  AM + I 75 → O (relative to I 100 & I 50 )  AM + Zn2 → O ∴ Recognition and hence application of such combinations can improve plant growth and production under drought stress.

 The alleviating effects of AM fungi : under moderate drought stress on corn grain yield, these fungi can enhance corn water efficiency under drought conditions and hence increase corn yield.  The important effects of Zn : on corn growth and production under drought, the combined effects of AM fungi and Zn can intensify the alleviating effects of AM fungi on corn growth and production under drought stress.