نشریه به زراعی نهال و بذر
سال بیست و پنجم شماره 3 (1388)

To study the effect of crop rotation and wheat residues management on grain yield, some agronomic characteristics of maize, and some properties of soil in second cropping system, an experiment was carried out in Experimental Research Farm of Orzoiyeh in Kerman Province for four cropping seasons (2000-2003). A split plot arrangement in a randomized complete block design was used with four replications. Wheat residue management at four levels (retention residue, burning and retention of residue every other year, removing residue, burned residue) were assigned to main plots, and crop rotation with three levels (1- wheat- cotton, wheat- corn, 2- wheat- soybean, wheat- corn, 3- wheat- corn, wheat- corn) were randomized in sub-plots. Results showed that yield and yield components, kernel protein content, organic carbon, available phosphorus, and bulk density in soil were not affected by wheat residue management, but available potassium in soil was affected significantly. Grain yield in residue retention treatment was 1150 kg ha-1 higher than burning residue. Organic carbon in retention and burning residue treatments were %0.65 and %0.59, respectively. Burning wheat residue increased available Potassium (204.95 mg/kg) in soil when compared with residue retention (180.04 mg/kg) and removing residue (178.48 mg/kg) treatments. Yield and yield components were not affected by crop rotation, but cotton in rotation had the highest potassium, phosphorus and organic carbon in soil. Based on these results and considering low organic carbon in soil and high temperature in summer in Orzoiyeh region, retention of wheat residue and rotation of cotton and maize after harvesting wheat are recommended. It is also suggested that the effect of wheat residue and crop rotation on grain yield and soil properties should be studied for a period of at least ten years.

The biological control agent, Trichoderma harzianum BI, was evaluated against the root-knot nematode Meloidogyne javanica in tomato.Tomato roots were inoculated by different concentration of Trichoderma harzianum BI using root-dip method. The pots were immersed in aluminum trays containing water 27 ° Ċ and transfered to a greenhouse. In greenhouse the concentration of 106 spore/ml of Trichoderma was effective for control of nematode root galls, root fresh weight, egg mass and the number of egg per mass reduced and shoot fresh weight increased. The number of root galls in treatment of 106 spore/ml was significantly greater than those of 103,104,105 spore/ml and control (without antagonist), but there were no significant differences among 106,107and108 spore/ml (p≤0.05). Results of quantitive changes in phenolic compounds in tomato cv. King Stone showed that, there were significant differences between Trichoderma inoculated plants and control.Total phenol content in plant inoculated with fungus and nematode was greater than those plants inoculated only with Trichoderma. The maximum phenol content was observed eight days after inoculation. According to these results T. harzianum can induce plant defence mechanisms (especially phenolic compounds) and reduces nematode disease rate.

To study the effect of planting date on root rot disease caused by Fusarium solani f.sp. phaseoli of Chitti bean (Phaseolus vulgaris L.), an experiment was conducted in Khomein Bean Research field Station in 2004 and 2006 cropping seasons. This experiment was arranged as split plot in a randomized complete block design with three replications. Three chitti bean genotypes (local Khomein, Talash, and COS16) were sown in four different planting dates (10 May, 25 May, 09 June, and 24 June). Combined analysis of variance showed that the effect of planting date on seed/pod, seed/plant, 100 grains weight, seed yield and root rot disease severity was significant at the 1% probability level and on pods/plant at the 5% probability level. Effect of cultivar on pods/plant, grains/plant, 100 grains weight and root rot disease severity was significant at the 1% probability level and on grains/pod and grain yield at the 5% probability level. Planting in 09 June and COS16 genotype produced the highest seed yield. Delaying planting date decreased disease severity. COS16 and local Khomein genotypes had the least and the highest disease severity, respectively.

Diurnal variations in net photosynthesis rate (A), stomatal conductance (gs) and transpiration rate (E) were assessed at the leaf surfaces of two pistachio (Pistacia vera L.) cultivars, in reference to diurnal fluctuations of leaf temperature (Tleaf), vapor pressure deficit (VPD) and photosynthetic photon flux density (PPFD). In this experiment, diurnal changes of net CO2 assimilation showed two-peaks pattern in which the first peak were appeared at 9:00 a.m. and 8:00 a.m. in ‘Badami’ and ‘Qazvini’ cultivars, respectively. The second peaks also emerged at 16:00, and the lowest assimilation rates were observed at 15:00 in both cultivars. The corresponded PPFD with the highest net assimilation rate were achieved at 1500 and 1150 µmol CO2 m-2 s-1 in ‘Badami’ and ‘Qazvini’ cultivars, respectively. It is interpreted that stomatal conductance in 'Badami' was primarily limited by VPD and leaf temperature higher than 3.5 kPa and 32 ° C, respectively. However, in ‘Qazvini’, the VPD higher than 3.8 kPa and leaf temperature above 33 ° C were the restricted factors. Quantum yield of CO2 fixation was decreased at leaf temperatures higher than 24 ° C. Generally, diurnal patterns of leaf gas exchange characteristics revealed that afternoon depression of net photosynthesis was mainly affected by stomatal factors, however, non-stomatal factors involved in this event, too.

To study the effect of sowing date on some agronomic characteristics, seed yield and its components of rapeseed genotypes an experiment was conducted in Moghan Agricultural Research Center in 2005-2007 cropping seasons. A split plot arrangement in a randomized complete block design with three replications was used. The main plot included date of sowing (22 Sep., 06 Oct., 21 Oct. and 05 Nov.) and five rapeseed genotypes (Hayola401, Y3000, RGS003, Sarigol and Zarfam) ware assigned in the sub-plots. Combined analysis of variance for two years, showed that agronomic characteristics, seed yield and yield components were significantly affected by sowing dates. The highest seed yield obtained in third sowing date (2984 kg/h). There was significant differences between genotypes for agronomic characteristics, seed yield and its components. Y3000 had the lowest and Zarfam had the highest number of days from emergence to flowering and physiological maturity. Zarfam produced the highest number of pods per plant and Hyola401 produced the highest number of seeds per pod. The sowing date×genotype interaction for seed yield was significant at the 5% probability level. Third sowing date (21 Oct.) and Hyola401 hybrid with seed yield of 3820 Kgha-1 produced the highest seed yield.

Haploid breeding is the most efficient method for the production of pure lines. In this research, tomato microspore culture method was studied to develop an embryogenesis protocol. The influence of several stresses, i.e. low and high temperatures, starvation and colchicine applied on isolated tomato microspores on the induction of microspore embryogenesis was investigated. Microspores in different stages of development were isolated from surface-sterilized flower buds and cultured in medium AT3 or starvation medium B, with or without colchicine, at different temperatures for varying lengths of time. After the stress treatments, microspores were transferred to modified AT3 medium supplemented with phytohormones and incubated at 25°C in the dark. The results showed that the late-uninucleate stage microspore, B medium and magnetic stirring were the best developmental stage, medium and method, respectively for isolating viable microspores. Treatment with colchicine (25µM) in combination with low temperature at 4°C for 72h also induced more than 35% of the cultured tomato microspores to divide symmetrically forming calli and embryoids

To evaluate response of different wheat (T. aestivum L.) genotypes to drought stress in terminal growth stages, a split-plot arrangements in a randomized complete block design with three replications was conducted in Darab Agricultural Research Station in 2001-2002 and 2002-2003 cropping seasons. Main plots included three irrigation regimes: I1: five times irrigation in: stem elongation, booting, flowering, milk and dough stages, I2: four times irrigation in; stem elongation, booting, flowering and milk stages; I3: three times irrigation in; stem elongation, booting, and flowering stages and five bread wheat genotypes including: Chamran (local check), S-78-11, S-75-20, S-79-10 and S-79-18 were assigned to sub plots. Combined analysis of variance showed that effect of irrigation, genotype and irrigation × genotype on grain yield, grain weight, grain per spike, spike per m2, water productivity, harvest index and biological yield were significant. Among the grain yield components, grain weight was more affected by deficit irrigation. Water productivity in I1 and I2 irrigation regimes were similar, but significantly more than in I3. However, grain yield, grain weight, harvest index and water productivity in S-78-11 were significantly lower than other two genotypes. Chamran, S-79-10 and S-79-18 had significantly higher grain per spike than the other two genotypes. The highest spike per m2 was for S-78-11. S-79-18 and S-78-11 had the maximum and minimum biomass, respectively. Grain yield, grain weight, grain per spike, harvest index and water productivity of Chamran, S-79-10 and S-79-18 did not differ, and were higher in these genotypes. On the basis of the results of this research, since in I3 grain yield was severely reduced, it would not be considered as an efficient irrigation management strategy, while four times irrigation regime could be considered as a suitable irrigation strategy for saving of irrigation water. Chamran and S-79-10 had higher grain yield in all three irrigation regimes, and can be considered as suitable genotypes under both moisture stress and non-stress conditions.

This study was conducted to evaluate the effect of drought stress on 22 durum wheat genotypes. Different characteristics such as grain weight per spike, plant biomass, 100 grain weight, free proline content in leaves, and percentage of cell membrane damage were studied in greenhouse and laboratory conditions. Genotypes were sown under normal irrigation and moisture stress conditions. In stress experiment irrigation was applied until spike emergence stage. Leaf samples were taken from flag leaf under stress and non-stress conditions at flowering stage. Genotypes were then compared by calculating stress tolerance index (STI). Results indicated that genotypes, 12, 21 and 13 (Marvoid, Saymareh, and G13, respectively) performed better as compared to the others for drought stress tolerance, proline content, cell membrane stability, and grain weight/spike. These genotypes were selected as tolerant to drought. On the other hand, the genotypes 11, 3, and 9 (Garagilchik, 2019/01/23, and 11-11-1-3, respectively) were susceptible with lower proline content in leaves and higher cell membrane damage. It was also shown that there was a highly positive relation among grain weight/spike, STI, proline content and cell wall stability, therefore, these attributes can be used as selection criteria in the breeding programs.