THE SCIENTIFIC JOURNAL OF AGRICULTURE (SJA)
Year:2005 | Volume:27 | Issue:2|Papers Count:15

Embryogenic callus induction is a critical step for most of gene transformation methods to maize. Unique explants immature embryos for this kind of callus prepration generally limit their production to one or two months a year. Alteration with mature embryo from seed can prolong callus induction during all seasons of the year. In order to reduce this limitation, by using mature seed a factorial experiment inducing seven important commercial inbreds of Iran and two media conducted via a completely randomize design was performed. The results showed that callus induction are possible in all lines, if the coleorhizae portion touches medium surface. For most of inbreds mMS2 was better than mN62 but mN62was better for Mo17 and TVA926. Callus induction speed and durability were depended only on genotype. Lines L105, S61 and TVA926 induced callus in.2 to 3 days but for the other took 8 to 11 days: Most durable cali belonged to S61 (328 days) and K722 (291 days) while cali of the other were very in durable, with 68 days for B73 to 109 days for TVA926. Statistical survey of four maintenance media on best line, S61, reveled that N62Ag medium was better than the other maintenance media. Callus of the revealed mentioned line on this medium grew more and finally produced few embryogenic cali but no plant.  

This investigation was carried out to study the fauna of the stone fruit trees aphids during 1999-2000. The specimens were collected once a week from infested leaves and branches of the trees of plum, peach, apricot, almond and cherry from Mashhad orchards. In this study 16 species of aphids were collected and identified from the stone fruit trees ef this area and are as follow: Aphis citricola * V d G., A. craccivora* k., A. gossypii * G.,  Brachycaudus amygdalinus s., B. cardui (L.). B. dicaricata * s., B. hlichryi(K.), B. persicae * (P), B. pilosus ** (M.). B. Prunicola (K.), B. schwartzi (B.). Hyalopterus pruni (S.),  Pterochloroides persicae (CH.). The species that is marked with*, are reported on new hosts (1-apricot, plum., peach; 2- plum., sloe tree., Prunus divaricata caspica k.-E; 3-Almond; 4-sloe tree; 5-Plum., sloe tree; 6- plum., peach ); and the species that is marked with**, is a new record for Iran.    

The migratory locust Locusta migratoria L. is one of the most important acridids that causes heavy losses in sugarcane fields in Khuzestan. Because of its occasional damage, there has been less attention to this problem. To apply a safe control method, a study of biology and natural enemies is necessary. The biological studies were conducted under field and laboratory conditions in Khuzestan province in 1996- 1999. The model of egg capsul distribution and effect of natural enemies were investigated. The biological studies showed that this pest had 3 generations under the field conditions. The population of the first generation was low and increased to overlap the second and third generations, which occurred in July and Agust. Hibernation occurred as egg, but the pest had 5 generations under laboratory conditions. It is concluded that the grasshopper has no obligate diapauses. The model of egg capsul dispersion was clumped. The wasp Scelio flavibarbis was parasitized 44 - 52 % of the egg capsuls during 1996-1999. It is recommended that the wasp population in the field must be supported by the use of careful cultivation operations.  

Seed priming is a technique to improve seed and seedling performance. The purpose of priming is to reduce germination time and improve stand and percentage of germination. This research was conducted under laboratory conditions in the University of Tehran in 2002. In this study sugar beet seeds of two genetically monogerm varieties (Rasoul and 276) were selected and primed with polyethylene glycol (PEG) over various times (3, 5 and 7 days). After determining the optimum water potential and time for priming, the primed and control ( unprimed ) seeds were tested under simulated drought stress using PEG solutions ( 0, -2, -4 and -6 bars). Germinated seeds were counted every 24 h. for 10 days. The numbers of normal seedlings were also detected. Results showed that the best osmotic potential for priming of sugar beet seeds was -1.2 MPa for 5 days, which increased germination up to 8% and 1% for 276 and Rasol varieties, respectively. Drought stress decreased germination percentage for both primed and non-primed seed. However, this reduction was lower for primed seeds as compared to non-primed seeds. Mean germination time -(MGT)was affected by drought stress, but primed seeds reached to their 50% germination in 0.7 to 1.4 days earlier.  

A study of Preimaginal development of sweet potato whitefly Bemisia tabaci Genn. (Hom., Aleyrodidae) was done on melon, cucumber and okra under laboratory conditions (15±1, 25±1, 30±1ºC, R.H. 60±5%and a photoperiod of L: D 14:10 hours). The results showed that total preimaginal development period on melon was 51.51, 21.42 and 15.7 days at 15,25 and 30°C, respectively. On cucumber and okra this rate was 51.97, 20.99, 13.42 and 66.7, 32.13 and 17.02 days, respectively. Data analysis showed that there was a significant difference in preimaginal development of this pest on melon, cucumber and okra. There was also a significant difference among preimaginal development on melon, cucumber and okra at 15°C. Further there was a significant difference between developmental stages of time egg and nymphal stages on okra, melon and cucumber but no significant difference was observed at pupal stage on these three host plants at 25 and 30°C.  

According to the studies carried out from July to December 2000, Megaselia scalaris (Loew) was identified as an important pest of button mushroom, Agaricus bisporus (Lange), in Karaj mushroom farms. This species is a cosmopolitan and polyphagous one. The larvae feed on and bore tunnel in the stalk and pileus causing quality and quantity loss of the yield. The larvae are vermiform, and lack definite head capsule. The pupa is coarctate and has a pair of large respiratory horns. The adults are distinguished from the other species of the genus Megaselia by face chaetotaxy, long anal tube with 2 long hairs at distal, existence of 10 large setae at the back of hind tibia and costal vein that is longer than half of the wing length. The biology of the pest was studied in laboratory conditions (20±l°c, Rh>80% and 16L: 8D photoperiod). The result indicates that developmental time in males and females was 22.55±0.081 and 23.66 ±0.075 days, respectively. The incubation period, larval period (including3 larval stages) and pupal period, were 1.04 ± 0.007, 8.33 ±0.07 and 10.77±0.055 days, respectively. The adult longevity of males and females in food free condition was 2.87 ±0.091 and 3.44±0.116 days, in pitmass media 3.10±0.126 and 3.27±0.106 days, in 5% glucose 6.29±0.177 and 7.07± 0.186 days, in 5% glucose and pitmass 5.42±0.156 and 6.49 ± 0.197 days and in natural condition of mushroom cultivation was 5.19 ± 0.178 and 5.75 ± 0.168 days, respectively. The juvenile mortality was 25.71 ±5.14 percent. Sex ratio in artificial feeding condition (Malt, Yeast, and Agar) was 1:1.38 male to female and in natural cultivation condition of mushroom it was 1:1.44 male to female. Net reproductive rate (Rº) and intrinsic rate of increase (r) were 29.4 and 0.132, respectively.  

Platytelenomus hylas Nixon is the egg parasitoid of Sesamia spp. Efforts for multiplication and releasing of the wasp in corn and sugarcane fields for biocontrol purpose of the stem borers  (Sesamia spp.) indicate that the wasp has high host specificity. Consequently, the egg of the Sesamia was used for rearing and multiplication of the wasp. The eggs in test tube were exposed to the parasitoid wasps. After parasitising, the host eggs were incubated for undergoing embryonic and immature stage of parasitoid. The emerged wasps were fed by honey syrup and preserved for releasing. The mean number of eggs per female wasp that can be parasitized and host preference of the wasp were determined with and without using olfactometer for two species of the S.cretica and S.nonagrioides. Results show that host eggs are successfully parasitised. The length of growth period was 10.5- 15 and 9.5-13 days in 26±1°C and 29±1°C, respectively. The mean number of eggs that were parasitised per female wasp was 70.8±4.28. Both methods of host preference experiments show that the wasp preferred eggs of S.cretica to S.nonagrioides.  

In order to study the effects of heat stress after anthesis on six wheat (Stork, Showa, Green, Star, Chamran and Fong) and two barley (Jonob and Sarasary 6) cultivars, two field experiments were conducted in delayed and optimum sowing dates. Plants in delayed sowing date experienced heat stress in after anthesis growth stage. Study of stress tolerance index (STI) and stress susceptibility index (SSI) for grain yield and grain weight indicated that the highest and the lowest STI for grain yield was in Jonob and 00 cultivars, respectively. Green and Stork STI's had the highest and the lowest grain weight, respectively. Stork and Jonob were sensitive and insensitive cultivars to heat stress respectively. Higher SSI for grain weight in late maturity cultivars such as Green and Star was related to the delay in anthesis and contact of grain growth period with heat stress, In early mature cultivars such as Fong with early anthesis, grain growth period was before heat conditions, while stress susceptibility for both grain yield and grain weight was the highest in Fong cultivar.  

Four genotypes of durum wheat cultivars comprising PI40100, Dipper-6, Oste/Gata, Shova and F2 and F3 progenies derived from crosses between some of them were evaluated using a randomized complete block design in 2001. Agronomic traits including days to heading, days to anthesis, days to maturity, plant height, spikes length, number of spike per m2, number of grain per spike, grain weight per spike, 1000-grain weight, grains yield, biological yield and harvest index were evaluated. The results showed that grain weight per spike (18.7%), number of grains per spike (14%), number of spikes per m2 (12.5%), harvest index (12.4%) and grain yield (11.2%) had the highest genetic coefficient of variation, respectively. Statistical analysis showed significant differences between genotypes for all traits except for the number of spike per m2 and biological yield. Days to heading, days to anthesis and days to maturity had the highest broadsense heritability. The lowest broadsense heritability was observed for the number of spikes per plant. Study of correlation analysis indicated that grain yield was correlated significantly with harvest index (0.92), number of grains per spike (0.91), grain weight per spike (0.93) and number of spikes per m2 (0.87). Based on stepwise regression analysis, harvest index and number of grains per spike explained 96.2% of grain yield variation. Path coefficient analysis indicated that harvest index, biological yield and the number of grain per spike had the most direct effect on grains yield, respectively while the number of grain per spike had the most indirect effect on grains yield via harvest index.  

Quality of soil maps for different land uses is affected by variability of soils in the map units. Thus, accuracy of procedures used for crop recommendation would be questionable. This study was conducted for statistical evaluation of the procedure presented by Sys et al. (1991) for land suitability evaluation in Farrokhshahr area, Chaharmahal and Bakhtiari province. Results from thirty-one pedon in a selected detailed map unit were compared with the results obtained from representative pedon. Purity of suitability class was 16.1 and 24% at series and phases of series levels, respectively. According to cluster analysis, considering land indices, similar to that of the reference pedon, purity improves to 32.2 and 48%. These results also indicate that the use of land suitability class, because of its extended range and generalization of evaluation results derived from reference profile to the whole land unit, can be miss-leading considerably. For this reason, it is advised to take care in the interpretation of the results, at least when the suitability of a land is at the vicinity of the evaluated class indices. Also, due to low purity in soil map units, the use of this method in the level upper than phases of series level and also precision agriculture is not recommended. Combined new techniques like geostatistics, GIS and RS can be used to improve soil Sampling and mapping methods.  

To evaluate the effects of plant growth regulators on rooting of stem cutting leafy and leafless cutting of bougainvillea, Indolebutyric acid (IBA) and Naphthaleneacetic acid (NAA) and their combinations were applied in the spring. After selection of suitable mother plants, shoots in 0.8-1.2 cm diameter were cut for preparing cuttings. In this research, two auxins, IBA and NAA at concentrations of 0, 1000, and 2000 mg1-1 as well as the combinations of concentration of 2000 mg 1-1 of these two auxins were used (1000 mg-l IBA and 1000mg-l NAA). The cuttings were treated with auxin solution for 30 seconds and immediately transferred to rooting sand medium in a plastic tunnel. Treatment was evaluated in a completely randomized design with a factorial arrangement with three replications. Each replication .consisted of 10 cuttings and the means were compared using Duncan's multiple range tests. The results showed that the best rooting of cutting with the high percentage of 90 was obtained for leafy cutting. The highest number of roots was obtained in leafless cuttings (9.23 roots per plant) at 2000 mg 1-1 IBA. The best effect of different levels of auxins on root length (5.79 cm) was obtained leafless at 1000 mg 1-1 NAA. The leafless cuttings had the highest root diameter (1.06 mm) at 1000 mg 1-1 NAA. Also, the highest root dry weight (69 mg) was observed at 2000 mg 1-1 IBA for leafless cuttings. Also, it was indicated that the factors like rooting percentage, number of roots and root dry weight in leafy and leafless cuttings were significantly more than the control (P<0.05).  

Soil compaction influences soil structure, permeability, porosity, pore size distribution, soil water retention. When a soil is compacted, large soil pores change to small pores, and therefore, matric potential and soil water holding capacity will increase. These changes can cause impediments in mass flow and diffusion of nutrients in soil. The aim of this study was to investigate the movement and distribution of some macro nutrient in soil as affected by soil compaction. The soil was packed into PVC columns to a bulk density of 1.4 to 1.95Mg m-3.Three levels of N, P, K fertilizer (200, 130 and 220 mg/kg soil) were applied. The soil columns were irrigated for 5 times and effluents were continuously collected and analyzed for the 3 elements. At the end of the experiment all the soil columns were divided into 6 parts and analyzed for measuring soil physical and chemical properties as well as N, P, K. The results showed that the movement and leachate of N and K in the soil columns were reduced as the soil compaction increased. But P transport was in contrast. The reason for the movement of nitrogen in low level of compaction is the existence of macro pores for preferential flow and suitable condition for nitrification. The mechanisms of potassium movement were the same as nitrogen. Phosphorus transport in high compacted soil can be related to increased ion concentration, high moisture and diffusion coefficient in the soil. The larger applications of fertilizer practiced on compacted soil to overcome crop yield losses increase the potential for nutrient losses.    

In order to study the effect of genotype and nitrogen levels on the grain growth of rapeseed, an experiment was conducted in a split plot design with four replications in 2000-2001 at Shahid Chamran University, Ahvaz. Two cultivars, PF7045/91 and Hyola308 were assigned in the main plots as main factors and four nitrogen levels, 100,150,200 and 250 kg N/ha in sub plots. In this study, the analysis of grain growth by measuring grain filling period and grain filling rate was determined. A significant difference was observed between two cultivars for grain growth pattern. It was no revealed that effect of nitrogen levels on grain filling period is significantly higher that the effect of nitrogen levels on grain filling rate. There were no significant relations between grain filling and effective grain filling period with single plant grain yield. Also, a significant positive relation was detected between grain filling period and seed. Oil percentage. The highest grain yields of PF7045/91 and Hyloa 308 cultivars on the basis of single plant records were obtained at the nitrogen levels of 250 kg N /ha and 150 kg N/ha, respectively. Also, the highest grain filling period and seed oil percentage were obtained at the level of 150 kg N/ha for both cultivars. However, the effect of nitrogen on grain filling rate and grain filling period was more than the effect of nitrogen on grain yield in Hyola308 as compared with PF7045/91 cultivar. It appears that Hyola 308 had higher N efficiency for reproductive plant parts.  

Fodder amaranth crop (as a new crop) is recently expanding in many tropical agroecosystems. Also, it is a good alternative crop in rotation with cereal crops in sustainable agriculture system. For the first time in Iran, in 2002, 5 cultivars of fodder amaranth were planted in Ramin (Molasani) Agricultural faculty, near Ahvaz. Statistical design was RCB with 3 replications. Results have shown that total forage yield was between 15 to 32 ton/ha. Pooping CV had a highest forage yield (32 ton/ha). Also, Trigin Cv. With 14/8% protein had a highest forage quality. Therefore, it seems that amaranth crop especially forage cultivars will have a good potential yield for both quality and quantity parameters in Khozestan. So, more agronomic trials are required.