Crop Production
Year:2008 | Volume:1 | Issue:2|Papers Count:7

Milk thistle is used traditionally as a hepaprotective agent and supportive treatment of liver disorders. The most problems in Milk thistle harvest are tall height, seed shedding and being spinous. In this trial, effects of 3 native populations (p1: Isfahan violet flower, p 2: Ahvaz white flower and p3: Ahvaz violet flower) and 3 topping levels (t1: control, t2: topping in 7 leaves stage and t3: cutting back in first capitulum appearance stage) on qualitative and quantitative properties of Silymarin, Silybin, Isosilybin, Silychristin, Silydianin, Taxifolin , seed, tall height and days until blooming was studied. Experimental design was factorial and conducted as a randomized complete block design with 3 replications in experimental field of Ramin Agricultural and Natural Resources University (2006-2007). The results indicated that, seed yield in topping and native populations had not significant difference. Effect of topping on decrease of tall height was significant but population’s was't. Topping moreover creation stress caused delay in blooming and synchrony seed filling with high heat, thereupon, thermal stress increased medicinal active substances. Amount of medicinal active substances among popoulations were very difference. In p1 amount of silymarin was 2.81 and 2.09, silychristin 2.30 and 4.64 and isosilybin 3.63 and 4.90 fold p2 and p3 respectively. P2 had not silydianin. Amount of silybin in p 3 was 2 and 6.09 fold of p1 and P2 respectively. The results showed that effects of populations on medicinal active substances were much more than topping. P1 was 26 days more serotine than p2 and p3.

In order to determine combining ability, heritability and heterosis of some agronomic traits in rice, 4 pure lines were crossed with 2 cytoplasmic male sterile testers. Parents and their F1 progenies arranged in RCB design with three replications. Analysis of variance showed significant differences among genotypes for all traits, except for filled grains/panicle. Furthermore, the crosses effect was significant for all traits at 1% level. Existence of additive and non-additive effects was observed on controlling of given traits. Combining ability analysis showed that there was significant GCA for some of parents in all traits except for panicle length and tillers/plant. The highest GCA in yield (105.3 g/m2) was obtained for line 1. SCA was only significant for plant height (combinations: L1´T1 and L1´T2), panicle sterility and 1000-grain weight (combinations: L3´T1 and L3´T2). Share of additive and non-additive variations was not identical in various traits, and different values of heritability were observed based on genetic additive effect. The highest specific heritability (Hn) was observed for 1000-grain weight (41.7%). Average specific heritability observed for total grains/panicle, plant height and yield results in relatively low efficiency of selection of the lines with desirable characters. It seems that selection for further tillers and longer panicle will not be successful because of low specific heritability. The highest heterosis in yield (26.1%) was obtained for L1´T1 cross.

Present study was conducted to investigate the effects of different osmotic potentials (0.0 MPa, -0.4 MPa, -0.8 MPa and -1.2MPa) induced by NaCl and Polyethylene glycol-6000(PEG) as salinity and drought stress respectively on germination and early growth of two inbred lines of maize (Mo17 and B73). The objective was to compare the germination ability between tow maize inbred lines in salt and drought stresses and to determine factors (salt toxicity or osmotic stress due to PEG) inhibiting seed germination. The experimental design was completely randomized design with three replications in which factors were arranged as factorial. The experiment was carried out in a germinator (25±1oC, 40% relative humidity). Results of variance analysis showed that the effect of osmotic potential levels on germination index, germination percentage, length of root and shoot and seedling dry weight was significant. Germination and seedling growth appeared to decrease with increasing osmotic pressure. While this decrees was more considerable in seedling growth than in germination. It concluded that at each level of osmotic potentials the inhibitory effect of drought stress on germination was more drastic than that of salinity stress. The germination responses of inbred lines to the both stresses were nearly same. When seeds were transferred to unstressed condition, after 10 days of salinity treatment, there was some recovery. This showed that the main inhibitory influence of salinity on maize inbred lines seed germination was mostly due to osmotic effect.

Velvetleaf (Abutilon theophrasti) is one of the most important weeds of soybean fields in Golestan province. A field experiment was conducted in Gorgan agricultural research station in 2007 to determine the critical period for velvetleaf control in Williams soybean (Glycine max (L.) Merr.) Cultivar using a randomized complete block design with 4 replications. Treatments were included two sets of weed-free (weed-control) and weed-interference (unweeded) periods. In weedcontrol treatments, plots kept weed-free until the following growth stages at which time velvetleaf was allowed to compete for the remainder of the season: 2-trifoliate leaf (GDD=320), 4-leaf (GDD=520), 6-leaf (GDD=750), flowering (GDD=950) and beginning pod (GDD=1325). Unweeded treatments allowed velvetleaf to compete until soybean reached above-mentioned growth stages, when plots were maintained weed-free for the remainder of the season. In addition, study had interference and a weed-free control. Non-linear Gompertz and Logestic equations were used to determine critical weed-free period and critical timing for weed removal, respectively. The effect of weed-free treatments on pod number per plant and grain yield was significant, statistically. However, weed removal treatments have no significant effects on number of seeds per pod and seed size. All yield components except seed size and grain yield were affected significantly by weedinterference durations. Among yield components, pod number per plant had the highest correlation (r=0.97) with the grain yield. In contrast, the lowest change was that of seed size. Based on 5 and 10 percent acceptable yield loss, critical period of velvetleaf control in soybean were 20 to 45 (from 3-leaf to flowering stage) and 25 to 35 (4- to 6-leaf stage) days after emergence, respectively.

In order to investigate effects of optimum use of manure and nitrogen fertilizer on yield and yield components of corn single cross 704 (late maturing, non-prolific and dent) in different levels of irrigation water. A field study was conducted in 2005 year in agriculture experiment station of college agriculture, Arak University (34o 32′ N, 50o 31′ E; 1759 m above mean sea level). Design of experiment was randomized complete block with factorial arrangement with three replications. Nitrogen treatments were include 0, 92, 184 and 276 kg N ha-1, 46 kg N ha-1 + 2.5 ton ha-1 farm yard manure (FYM), 92 kg N ha-1 + 5 ton ha-1 FYM and 138 kg Nha-1 +7.5 ton ha-1 FYM and amounts 5, 10 and 15 ton ha-1 FYM and water factor include 50%, 75% and 100 crop water requirement. Results showed that with reducing nitrogen contents and irrigation water, yield and yield components reduced. Maximum yield and yield components was produced when nitrogen and water used for plants sufficiently. Chlorophyll content index increased when irrigation water amount was decreased. Chlorophyll content index has direct relation with nitrogen and increased linear by nitrogen amount and this relationship was affected by water amounts. Maximum grain yield of corn with nitrogen factor was produced with 138 kg N ha-1 + 7.5 ton ha-1 FYM and average of grain yield was 7555 kg ha-1 and water factor at optimum irrigation was produced average of grain yield 8756 kg ha-1. Maximum grain yield was produced with interaction effects of nitrogen and water in 138 kg N ha-1 + 7.5 ton ha-1 FYM and optimum irrigation.

This study was aimed to study the ways of removing dormancy period and accelerating pre-sowing tuber germination to provide simple tools to apply by farmers. For this purpose, intact tubers, exposed tubers to released Ethylene and sliced tubers were examined in respect to germination characters, bud length, starch, anthocyanin and chlorophyll contents and amylase activity. Relative amount of antocyanin was measured in buds and the area just below it. Results indicated that treatments had significant effects on all studied characters, except for mean bud number in 1% of probability level. Mean comparisons revealed that sliced tubers obtained higher values of studied characters, except for chlorophyll a content. The highest value for chlorophyll a content belonged to exposed tubers by Ethylen (released by banana), but differences were not significant. The highest bud length was seen in sliced tubers, but difference with ethylene treatment was not significant. The differences between sliced tubers with other treatments in respect to chlorophyll a, chlorophyll b and chlorophyll a+ chlorophyll b contents were significant. Results revealed that cutting the tubers is the best treatment to stimulate and accelerate bud germination in potato tubers. Cutting the whole or part of tubers can be adviceable as a proper management even in well-size tubers to stimulate and promote bud germination in potato. Also, Ethylen releasing fruits such as banana and apple which are readily accessable and available for farmers, can use as second approach to achieve bud germination stimulation.

In order to study the effect of sowing date and plant density on some quantitative traits and yield of sugar beet genotypes a field experiment was carried out at Sugar beet Seed Production Research Station of Karaj in 2006. Treatments arranged in a split, split plot experiment based on completely randomized block design with four replications. The main factors were two sowing dates as 14 April and 24 May. Sub plot were four plant density including 50, 75, 100 and 125 thousand plants per hectare and the sub-sub plots three sugar beet hybrids(428, 7112, and DS4027). The results showed that the green leaf number, crown dry weight, root dry weight, petiole length and root yield in first sowing date increased compared to second one, so on the second sowing date yield decreased 24.3% relative to first sowing date. Most traits improved with increasing plant density, especially root yield increased until 100 thousand plant ha-1. The maximum crown dry weight obtained from combination of the first sowing date and DS4027 genotype. Although, amounts of most traits of DS4027 was higher than 428 genotype, but they had equal root yield. There were significantly positive correlation between root yield and crown dry matter, total dry matter and dry leaf number. The best treatment obtained from combination of the first sowing date, 100 thousand plants per hectare and DS4027 genotype, however it recommends that the experiment carry out at several places and years to obtain the best sowing date and density and stable genotype.