فصلنامه پژوهش های تولید گیاهی
سال هفدهم شماره 3 (پاییز 1389)

This experiment was conducted for estimating the effect of row spacing and plant density on soil moisture change, wheat yield and water use efficiency in rainfed condition, using a three replicated randomized complete block design with factorial arrangement at Gorgan University of Agricultural Sciences and Natural Resources farm in Anbare-Ololum region in 2008-2009. The treatments that used were four plant density (125, 250, 375 and 500 plants per m-2) and two row spacing (12.5 and 25 cm). Results showed that soil moisture in the flag leaf appearance stage in 25 cm row spacing was more than 12.5 cm row spacing (19.61 vs. 17.82%). Also, Soil moisture content in the middle of stem elongation stage, was 26.82, 25.66 and 25.11% in plant densities of 250, 375 and 500 per square meter, respectively, which all were more than corresponding value for 125 plants per square meter (23.32%). Row spacing of 25 cm and plant density increasing from 125 up to 375 plants per square meter, increased grain yield (9.5 and 46%), dry matter production (6.5 and 50%), water use efficiency in terms of grain yield (0.07 and 3.7 kg ha-1 mm-1) and dry mater (2 and 17.5 kg ha-1 mm-1). Overall, wheat cultivation in this condition (rainfed cultivation, saline soil and seasonal growth rainfall about 250 mm), with 25 cm row spacing, from Mid-stem elongation stage using more densities via intensifying individuals and more plant height is more advisable than row spacing of 12.5 cm. In addition, the plant density of 375 was better than 125 plants per square meter, which is related to more surface coverage by higher density from stem elongation stage onward to pre-flowering. This can reduce radiation penetration and consequently soil surface evaporation and improve soil water content. More soil moisture storage at critical stages before flowering stage, increases dry matter production, grain yield and grain yield and dry matter production-base water use efficiency.

Puccinia recondite (Leaf rust) is an endemic disease in Iran; this disease can affect the productivity and quality of wheat, that occurring in all wheat growing regions. Genetic resistance to leaf rust of wheat is the most important strategy to control the diseases and 51 leaf rust resistance genes (Lr gene) are reported in wheat to provide resistance to leaf rust. This study aims to identify presence or absence of leaf rust resistance gene Lr32 in 48 Iranian wheat cultivars and lines using of infection-type data test and molecular markers linked to the leaf rust resistance gene. Infection-type analysis based on international method of Browder (1973) with 6 leaf rust pathotype known in Iran, revealed that, first, 17 out of 48 cultivars and lines have effective resistance to race virulence of leaf rust gene Lr32, second, 25 cultivars and lines foresight probability presence resistance gene Lr32 or genes with similar effect, and at last, absence of leaf rust resistance gene Lr32 revealed in 6 cultivars and lines. In molecular part, using known RAPD molecular markers (S49 and S421), evaluated possibility of present of 1100 bp and 640 bp fragments that closely linked to leaf rust resistance gene Lr32 in 48 wheat cultivars and lines. In according with expectation, detected 1100 bp and 640 bp fragments in near-isogonic's Lr gene but none of cultivars, lines and negative control line (Bolani and Agra Local), showed amplification related resistance gene fragments. Result of molecular Markers and infection-type data test showed absence of leaf rust resistance gene Lr32 in 48 Iranian wheat cultivars and lines.

Alternate bearing is one important problem in some citrus varieties like Citrus unshiu. An alternate bear tree doesn’t produce a regular crop in consequence years.Reduced fruit quality in "on year" and decreased quantity in "off year" cause economic loss to producer. To evaluate possibility of reducing this disorder, an experiment was conducted in randomize complete block design with 5 treatments: 1. Control; 2. Optimum using of chemical fertilizers; 3. Optimum using of chemical fertilizers and NAA spraying; 4. Optimum using of chemical fertilizer and 2,4-D spraying and 5. Optimum using of chemical fertilizer and Sucrose spraying with 4 replications in 4 consecutive years on Citrus unshiu mature trees. Control trees had the most alternate bearing during 4 years, as showed one "on" year, two consecutive "off" years and one "on" year, respectively. On the other hand, other 4 treatments reduced number of "off" years to one, during 4 years. Treatment 2 had the highest yield in "off" year and the lowest yield in "on" year. The smallest and lightest fruit in first, second and fourth years was allocate to Control. During 4 years, the lowest total yield was recorded in Control plants. In conclusion treatment 2 by reducing yield in "on" year, increasing yield in "off" year and reduce number of "off" years compare to Control and treatments 3, 4 and 5 by reducing number of "off" years and increasing fruit size in on years caused adjusting alternate bearing cycle, increase total yield in consecutive years, decrease fruit losses and improve marketability in Citrus unshiu.

Predicting seed viability would be extremely beneficial to seed producers and the prediction of seed viability depends on understanding the quantitative relationships between seed longevity, seed moisture content and storage temperature. Thus, theobjective of this investigation was to quantify relationship between temperatures, seed moisture and seed deterioration and determination seed viability constants in medicinal pumpkin, borago and black cumin. Five storage temperatures (30, 35, 40, 45 and 50 oC) and four moisture content levels (5, 8, 11 and 14%) were used. Seed viability equation is V = Ki-p/10 KE - CWlog10m - CHt - CQt2. The Ki is the initial seed quality constant, p is the storage period (days), m is moisture content (%, fresh weight basis), t is temperature (oC) and KE, CW, CH and CQ are constants. The results showed that KE was 3.4018, 6.7485 and 4.9701 for medicinal pumpkin, borago andblack cumin, respectively. The value of CW was 3.2148, 2.4195 and 1.2528 for three species, respectively. The value of CH for medicinal pumpkin, borago and black cumin was 0.131, 0.0665 and 0.0516, respectively and CQ for medicinal pumpkin, borago and black cumin was 0.00264, 0.000478 and 0.000478, respectively.

In order to study the effects of heat and drought at the end of the season, onyield and yield components of some agronomic traits in sixteen canola varieties,this experiment was carried our in Behbahan (30o, 37 N and 50o, 16 E) Instituteresearch. The experimental design analysis of combined in completly randomizedblock basis cration four condition to plant growth by different planting date and cut irrigation in the late staye the end of plant life. The four create condition were planting date at: 1-20 November, 2-20 November with cut the last irrigation, 3-20 December and 4-20 December with cut the last irrigation. Three replication was used in this experiment. Results showed that GDD on different humidity level or four condition at the flowering was different. Also flowering period in different condition showed the significant different. Heat and drought stress induced significant different (1% permability level) between four condition for seed yield, number pod per plant, number seed per pod, flowering starting time, oil percentage, oil yield. in four level difference Number pod per plant had the highest correlation with seed yield (83%), while there was not a significant correlation between yield and seed. Hyola variety had the highest yield therefor this variety recommended to all area same experimental place condition.

In this study, the effect of four citrus rootstocks {sour orange (Citrus aurantium), Bakraeii (C. reticulata × C. aurantium, Mexican lime (C. aurantifolia) and Volkamerlemon (C. volkameriana)} on Orlando Tangelo leaf chlorophyll content and mineral element concentrations (N, P, K, Ca, Na, Mg, Fe, Zn, Mn, Cl, Cu, and B) have been evaluated in completely randomized design with four replications. Budded Orlando Tangelo on above rootstocks were grown in pots containing calcareous soil (pH=8.2) in greenhouse. Results showed that rootstocks had significant effect on leaf chlorophyll content. Highest chlorophyll content was on sour orange rootstock. Rootstock types had significant effect on leaf mineral concentrations except of Ca, Mg, Cu and B. Leaf N and Ca concentrations on all rootstocks and Mn only on Mexican lime rootstock was lower than optimum range. Leaf Cl and Cu concentrations was higher than optimum range on all rootstocks. Scions on sour orange had highest Cl concentration and Na concentration was the highest on Volkamer lemon rootstock.

Samples with Stalk rot, yellowing and stunting symptoms from maize fields in western provinces of Iran were collected. After cultured of them on Eosin Methylen Blue (EMB) medium, twenty bacterial strains with metallic green color colonies on EMB medium were selected for identification tests. According to the biochemical and phenotypic characteristics, these strains were identified as Dickeya zeae. In order to, for evaluation of maize hybrids resistance to bacterial stalk rot, two methods including pseudostem injection and leaf puncture methods were used. In pseudostem injection method two hybrids, single cross 647 and 704, with most degree of stalk rot were placed in sensitive class (S), single cross 700 with medium resistance (MR) and single cross, 108 and 500 hybrids with least stalk rot were categorized as resistance varieties (R). The result from leaf puncture method has high correlation (r=0.93) with pseudostem injection method. Hybrids single cross 704 and 647 as sensitive varieties and single cross 108 as resistantvariety were introduced in this method.