THE SCIENTIFIC JOURNAL OF AGRICULTURE (SJA)
Year:2000 | Volume:23 | Issue:1|Papers Count:6

Estimation of water loss and evaluation of irrigation efficiency in two sugarcane plots in Field 201 of Haft-Tape Agro-Industrial Site in Khuzestan Province was the aim of this investigation. Sugarcane crop is planted in rows and irrigation is carried in block-end furrows. Three consecutive irrigation events in the months of July and August of the year 1997 have been evaluated. For each irrigation event, soil moisture samples were collected along furrows Samples were taken at points 50 meters apart from 3 depths, i.e. 0-33, 33-66 and 66-100 Centimeters .Samples were taken on a day preceding irrigation, and 48 hours after the start of irrigation, using soil auger. On the irrigation day inflow to furrows was measured along with data on advance and recession for each test furrow. Processing and evaluation of the collected field data reveals the following points. 1) According to this evaluation based on the allowable depletion of soil moisture, irrigation application time is late in relation to crop requirement. 2) Irrigation application efficiency is 69 percent in one field and 52% in the other one.3) Irrigation requirement efficiency in both fields is 100%.

Onion seedlings are capable of producing reproductive organs after vernalization. Low temperature requirement, and period before vernalization (45, 60 and 75 days after germination) were studied on the 3 onion cultivars (‘Ghermez Azarshahr', 'Texas Early Grano' and 'Pusa Red') in Climatology Laboratory of Physiology Department of Agriculture, Academy of Moscow in 1995. The time of flower stalk formation, number of green leaves, fresh weight of bulb, fresh weight of whole plant, dried bulb weight, largest bulb diameter and bulbing index, were evaluated. Initial growth of onion was influenced by cultivar and with senecensing, the difference in growth attitude was more prounced in this stage of growth. The bulb diameter and its fresh weight in of 'Texas Early Grano' was more than the other two cultivars. The minimum and maximum period for flower stalk formation was on 'Pusa Red' and' Texas Early' Grano, respectively. With the increase in plant age, period before vernalization, percentage of plant which produced flower stalk increased as well.The maximum bulb diameter and dried weight occurred for plants which were kept at relatively high temperature ( 22-24°C day, 19-21°C night). In this temperature, maximum diameter blub was observed in 'Gharmaz Azarshahr' and 'Texas Early Grano', however 'Texas Early Grano' showed maximum wet bulb weight.At relatively low temprature (15oCday, 7oC night), maximum and minimum bulb diameter and wet bulb weight was observed for plants, that transplanted to relatively cold temperature 75 and 45 days after germination respectively. Howere, 'Taxes Early Grano' was not affect by plant age.

The objective of this study was to investigate rhythmic growth of the Mediterranean young mandarin in controlled conditions. To determine the period of growth flushes during stem elongation, Mandarin orange plants were grown under alternate illumination, temperature (LD), continuous illumination, and constant temperature (LL) conditions. Elongation of shoot under continuous illumination (LL) and at constant temperature was strongly disturbed. In most cases, the shoot stopped elongating quickly. When elongation continued, no infradian rhythm city could be observed. However, under LD conditions an overt infradian rhythm of shoot elongation with a period of between 36 and 54 days was observed. There was a linear correlation between stem and leaf surface expansion (r=0.98).These data support the hypothesis that the infradian growth rhythm city in citrus trees results from a resonance between two circadian rhythms.

Four hundred and six isolates of Fusarium moniliforme were recovered from two corn seeds and diseased plants from two cultivars (3377, 3475). Seeds were collected from 12 different locations and plant materials from one location in the North Central United States. Isolates were purified and identified at species level. After that, all isolates were mated with standard testers of mating groups A and D. Results indicated that more than 97% of the population were in mating group A. In two locations all of the isolates belonged to this group, and in the other locations 3-6% of population in each area did not belong to this group. Both mating types A- and A+ were found in eleven regions, but mating type A-was not found in two locations. Mating types A-and A+ comprised (7-63%) and (13-30%) of the population in different regions, respectively. These results also revealed that 40% of the population was bisexual, and this kind of isolates formed (13-81%) of the population in each area.

To survey the sexual incompatibility system in Iranian isolates of the causal agent of partial bunt of wheat (Tilletia indica) which governs pathogenicity as well, in a Completely Randomized Design with seven replications, paired and nonpaired monosporidial lines were used to inoculate wheat heads in the boot stage. Paired lines which resulted in disease were postulated to be of different mating types (sexually compatible), whereas nonpathogenic pairs were postulated to consist of the same mating type (sexually incompatible). In all cases, nonpaired lines were nonpathogenic.The results of all possible combination of 15 monosporidial lines showed that heterothallism is controlled by at least five postulated alleles at one locus.

The present article is an attemp to summarize some theories which have been reported about the origin and the Phylogeny of rust fungi in connection with their host plants. With this aim, the historical development of these important plant pathogenic fungi is discussed in relation with a geological time table and in the light of continental drift.The phenomena of "biogenic radiation" and "hologenetic ladder" of rust fingi are redefined and illustrated in this paper.