AGRICULTURAL RESEARCH
Year:2006 | Volume:6 | Issue:1|Papers Count:11

Almond is the second important nut fruit in Iran with 152846 h. planting area and 107445 ton production in 2002. Decline disease resulting in death of almond trees is one of the damaging problems in almond gardening. During 2000-2003 almond gardens of East Azarbaidjan, Chaharmahal-Va-Bakhtiari, Yazd and Semnan provinces were surveyed and necrotic and/or cankerous tissues of root and crown of almond trees with decline, poor growth, yellowing, wilting and death symptoms on foliage were sampled. Small segments of infected tissues were disinfected with NaClO 0.5 % and cultured on PDA, acidified PDA, CMA-PARP media. Phytophthora cactorum, Verticillium dahliae, Armillaria mellea, Rosellinia necatrix, Fusarium oxysporum, F. solani, F. compactum, Rhizoctonia solani, Macrophomina phaseolina, Cylindrocarpon sp., Alternaria sp., Penicillium sp. And Trichoderma sp. were isolated. In pathogenicity tests, Phytophthora cactorum, Verticillium dahliae, Armillaria mellea and Rosellinia necatrix were highly pathogenic on 2-3 years-old almond seedlings and caused root and/or crown necrosis resulting in sharp foliage symptoms and death, but tissue necrosis symptom was observed on crown area of those inoculated with Rhizoctonia solani and Macrophomina phaseolina and roots of inoculated seedlings with Fusarium spp. Poor foliage symptoms appeared only in R. solani and F. oxysporum treatments. An isolate of Cylindrocarpon sp. was pathogenic only on 6-months-old seedlings. Four previous described fungi are principle soil-borne phytopathogenic fungal agents of almond trees decline and death, but are not the only causal agents. So a complex of soil-borne pathogenic fungi and noninfectious factors such as deep planting of seedlings, wrong irrigation methods and nonsuitable gardening practices are the causal agents of almond decline and death.

Effect of different concentrations of putrescine on postharvest life of strawberry fruit, cultivar Selva in 5oC was studied. Fruits were immerged in 0.3, 0.5, 1 and 2mM putrescine as well as distilled water (control) for 5 minutes, then transferred into the ftidge (5oC) together with untreated fruits (dry treatment). The rate of ethylene production, tissue firmness, soluble solids content, titratable acidity and pH of fruits were determined 5, 9 and 13 days after the beginning of storage. Storage life of the strawberry fruits was significantly increased by the use of putrescine, so that the untreated and control fruits had 6 and 8 days storage life respectively, while the immerged fruits in 1 and 2mM putrescine were still suitable to be exposed in the market 12 and 14 days after the beginning of storage respectively. Ethylene production was decreased significantly by the use of putrescine. Untreated fruits (dry treatment) had the highest rate of ethylene production and the lowest rate was occurred in 2mM putrescine treatment at all determination times (5, 9 and 13 days after the beginning of storage). The use of putrescine also prevented the softening of fruit tissue during the storage and kept their firmness, so that, the 2mM putrescine treatment caused the highest fruit firmness at all determination times. Distilled water treatment (control) had the lowest fruit firmness 5 and 9 days after storage, while this was 13 days for the dry treatment. Soluble solids content, pH and titratable acidity of the fruits were not significantly affected by the use of putrescine, but the highest and lowest rate of titratable acidity were related to the 2Mm putrescine and dry treatment respectively at the three determination times.

In order to study the effect of plant spacing on yield and yield components of four sunflower cultivars a factorial experiment based on a randomized complete block design with 3 replications was conducted. The experimental treatments were four cultivars of sunflower Azargol, Zaria, Record and Mehr and four plant spacings of 30, 25, 20 and 15cm in 65cm interval rows. In this experiment, characteristics such as grain yield, biological yield, harvest index, number of unfilled grains per head and yield components (number of filled grains per head and 100 grains weight) were determined. The results showed that the effect of cultivar on grain yield, harvest index, 100 grains weight and number of unfilled grains per head was very significant. However the biological yield and number of filled grains per head were not affected by cultivar. grain yield, biological yield and 100 grains weight were very significantly affected by plant spacing. Azargol and Zaria cultivars had the maximum (4221kg/h) and minimum (3515kg/h) grain yield respectively. The effect of plant spacing on number of filled grains per head was significant. By decreasing plant spacing, the biological and grain yield were increased and yield components were decreased. Interactions between cultivar and plant spacing on grain and biological yield and number of filled and unfilled grains per head were significant. Maximum and minimum grain yield (5163 and 2380kg/h) were obtained by Azargol in 15cm spacing and Record in 30cm spacing respectively.

In this research, conveyance and distribution efficiencies of 5000 ha. Shawour irrigation and drainage network located at the Khuzestan province of Iran, were estimated using field measurement. For this purpose, the flow losses at some selected un-lining channels were calculated using inflow-outflow measurement method. Then based on this calculation, losses coefficients in unit length of the channels and the conveyance and distribution efficiencies of the channels using the exponential equation were estimated. The results show that the canals conveyance efficiencies varies between 34 and 83% and in average is about 60%. Also, the distribution efficiency of the channel network is from 45 to 86.5% and average is about 71%. These very low efficiencies of the Shawour irrigation network are very critical and disappointing. Therefore, in order to increase irrigation efficiencies, an application of water and soil resources have to be employed using management methods. Considering the results of this research, increasing the water application efficiency needs several modifications including: channel geometric modifications and lining.

The predaceous mites of the family Phytoseiidae were collected from field crops, orchards, forest and other plants in Guilan Province during three years faunistic survey (2003-2006). A total ten species and four genera belonging to the subfamily Typhlodrominae Scheuten were identified. The lists of identified species are as follows. One and two asterisks above the species name mark the species which have been recorded for the first time from Guilan Province and Iran respectively: A- Genus Typhlodromus Scheuten 1- Typhlodromus Kettanehi (Dosse) 2- Typhlodromus caudiglans Schuster 3- Typhlodromus commenticius. Livshitz & Kuznetsov 4- Typhlodromus recki. Wainstein 5- Typhlodromus tubifer. Wainstein B-Genus Paraseiulus Muma 6- Paraseiulus soleiger (Ribaga) 7- Paraseiulus triporus (Chant & Yoshida Shaul) 8- Paraseiulus talbii (Athias-Henriot) C- Genus Neoseiulella Muma 9-Neoseiulella tiliarum. (Oudemans) D-Genus Typhloseiulus Chant & McMurtry 10-Typhloseiulus subsimplex. (Arotunjan).

Effect of 290 isolates of bacteria from cucumber rhizosphere were studied as potential biocontrol agents for control of cucumber wilt disease caused by Verticillium dahliae. 37% of bacterial isolates inhibited growth of V. dahliae. Inhibition ability on fungal growth was varied among bacterial isolates, ranged from 12.5-49.93% in dual culture test, from 22.24-84. 54% in volatile test and 60.84-96. 40% in antibiotic tests. Effective bacterial isolates were identified as Bacillus subtilis (B1 B2, B4), B. pumilus (B3), Pseudomonas fluorescens bv. III (P1) and P. fluorescens bv V (P2, P3, P4), according to biochemical, morphological, nutritional and physiological testes. spore germination of V. dahliae was decreased by P. fluorescens bv III (P1) and P. fluorescens bv V (p2, P3, P4) according to siderophore production test. In fungicide testes on bacterial isolates Benomyl, carbendazim, thiofanate metyl and captan no observed any inhibition on growth of bacterial isolates. B. subtilis (B1) was decreased disease severity, increased plant height, shoot and root dry weight in the infected and non infected to V. dahliae in the greenhouse conditions. In seed coating and soil drenching methods similar result had been obtained using B. subtilis (B2).