Effect of Deficit Irrigation at Different Growth Stages on Wheat Growth and Yield

In order to evaluate the effect of deficit irrigation at various growth stages on wheat growth and yield, a field experiment was conducted in the 2008-2009 growing season based on the completely randomized block with four replications at the experimental farm of the College of Agriculture, Shiraz University, Shiraz, Iran, located at Badjgah. Treatments involved 13 irrigation regimes which applied in stem elongation, heading and grain filling growth stages. The highest seed yield （4,333 kg-ha-1） and the lowest ones （1,377 kg＇hal） were obtained from T1 （100% field capacity （FC） in all growth stages） and T13 （50% FC in all growth stages）, respectively. With limitation in water amount seed yield was diminished, but this trend was not significant at T4 （100%, 100% and 50% FC） and TI 1 （100%, 100% and 75~/0 FC）. Stepwise regression results revealed that, seed number per spike had the largest contribution （partial R2 = 0.72） in seed yield variation. Also at TI, T4, and TI 1 treatments （well water treatments） as well as TI3 （sever stress） head number m2 contribute most in seed yield determination （partial R2 = 0.96）. It can be concluded that water shortage during the grain filling period and its allocation to the other consecutive crop, can increase crop production in southern regions of Iran.

Recombinants for Enhanced Productivity and Drought Tolerance in Barley （Hordeum vulgare L.）

In an attempt to enhance productivity as well as drought tolerance of barley cultivar, a 5 × 5 diallel cross involving rainfed cultivars was made. Of the 10 crosses, cross K603 x K560 was most promising as it yielded highest number of recombinants （21 in irrigated and 36 in rainfed conditions）; the cultivar K506 was considered as drought resistant （drought susceptibility index 〈 1）. A total of 22 out of 64 and 18 out of 59 most promising F2 recombinants in irrigated and rainfed conditions, respectively from 6 crosses were evaluated for yield, harvest index as well as proline content. All the recombinants selected under rainfed condition （including a few from irrigated condition） showed enhanced level of proline content coupled with high grain yield and harvest index. Further, a total of twenty-nine segregants （12 rainfed and 17 irrigated derived cultures） showing significantly higher values of proline content and grain yield were grown during 2007-2008 under both the environments, rainfed and irrigated to determine the geometric mean （GM） and drought susceptibility index （S）. The segregants （Culture No. 8, 10 ＆ 13） derived from cross K 603 × K 560 and culture No. 5 from K 560 × RD 2508 gave maximum mean yield under rainfed and geometric mean coupled with lower drought susceptibility index （S）. Also, it has been observed that the transgressive segregants selected from limited water environment （rainfed） performed better than those selected from irrigated environment for higher grain yield and drought tolerance.

Detection of Aflatoxin from Some Aspergillus sp. Isolated from Wheat Seeds

Ten seed borne fungi （Alternaria sp., Aspergillus sp., Aureobasidium sp., Cladosporium sp., Dreschslera sp., Penicillium sp., Rhizoctonia sp., Stemphylium sp., Mueor sp. and Rhizopus sp.） were isolated and identified from two wheat varieties, the highest frequency of seed borne fungi was observed on wheat cultivar site Moll4 Alternaria sp.. Their mean and standard deviation was （5.5 ~ 1.69） while the lowest frequency fungal isolated was Dreschslera sp. and Rhizopus sp.. Their mean and standard deviation was （0.1 ~ 0.64）. The aflatoxin-producing isolates appeared as gray or black colonies in the UV photographs, whereas nonproducing isolates appeared as white colonies, the plate five colony four （P5CO4） showed the positive results which means the presence of aflatoxin as compaired to the control which showed the ngative results. Ammonium Hydroxide Vapor-Induced Color Change method used which the dish was inverted and 1 or 2 drops of concentrated ammonium hydroxide solution are placed on the inside of the lid. The undersides of aflatoxin-producing colonies quickly turn plum-red after the bottom of the Petri dish has been inverted over the lid containing the ammonium hydroxide aspositive result in （P5CO4） and （P7CO4） observed. Essentially no color change occurs on the undersides of colonies that are not producing aflatoxinsthis indicate to the negative results （control）. The main objective of this study is to isolation, identification and rapid detection of aflatoxin from wheat seed borne fungi.