جستجوی مقالات مرتبط با کلیدواژه « ماده خشک تجمعی » در نشریات گروه « زراعت »

To evaluate the effect of different cover crops management on the trend of growth indices of common bean (Phaseolus vulgaris) during the growth season in the presence and absence of weeds, an experiment was carried out as a factorial experiment based on the randomized complete block design with three replications in 2012-2013 growing season at the research farm of the Faculty of Agriculture, Ferdowsi University of Mashhad. Experimental factors were type of cover crops in three levels of erseem clover (Trifolium alexandrinum L.), rye (Secale cereale L.) and intercropping of berseem clover+ rye (50:50), in two levels of seeding rate (recommended density and additive density), and three levels of mulch managements including herbicide+ mulch (cover crops killed by glyphosate and left the dead mulches on the soil surface), harvest+ mulch (cut the live cover crops and left them on the soil surface) and harvest (cut the cover crops and carried them out of the field). Results indicated that all treatments had significantly effects on the total weed density and dry weight and the maximum value of all growth indices. According to this, the LAI of common bean at chemical control (4.68), hand- weeding (3.96) and additive density of clover + rye with herbicide + mulch were the highest and total weed density and dry weight in this treatment, were the lowest. According to the results, the TDM at mentioned treatments were 747.43, 708.49 and 719.77 g.m-2 and had the highest values. In cover crop treatments without herbicide application, remaining the cover crop residue was better than removing cover crop from soil surface. In addition, CGR (g.m-2.day-1) and RGR (g.g-1.day-1) of common bean had the similar trends to LAI and TDM. It was concluded that the additive density of clover + rye with herbicide+mulch was the best combination to achieve to highest values of common bean growth indices.

A suitable planting date is an important management tool to determine the best match between phenological stages of plant growth with the environmental factors affecting them. Indigo is known for the natural blue colors obtained from the leaflets and branches of this herb. In addition to indigo dyes, it has been used medicinally to purify the liver, reduce inflammation and fever and to alleviate pain. Determining the proper sowing time for the sowing indigo plant is highly important that should be based on the climate of each region separately. The objective of this research was to determine the effect of sowing date on growth and biological yield of indigo plant in Shahrood region.
This experiment was carried out on randomized complete block design with three replications in the experimental field of the University of Shahrood, Iran, in 2011. Treatments were three planting dates (18 June, 3 and 18 July). Plant density was 50 plants per square meter. The distance between the plants on and between the rows was 10 and 20 cm, respectively. Sampling was conducted in six-stages (every 15 days) randomly in 0.25 m2. Equation 1 was used to calculate the growth rate.
CGR = (Equation 1) Y = (Equation 2)
In this equation, W1: dry weight in the first sampling, W2: dry weight in the second sampling, SA: sampling area (m-2), t1: first sampling time, t2: is the second sampling time. To do this, three parameters sigmoid function [Eq. 2], were fitted to dry matter accumulation variation during the season (Equation 2): In the equation 2: Y is the cumulative dry matter content at any time (x) of growing season, b: is the slope of increasing and xo is the time (in degree days) of reaching to 50% dry matter accumulation. Gaussian function parameter [Eq. 3] was fitted to the crop growth rate data variation: Y = (Equation 3) GDD (Equation 4)
In equation 3: Y value is crop growth rate at any time (x) of growing season, b: is the slope of increasing and x0 is the time of reaching plant to the maximum CGR. In this study, instead of day, we used growing degree days (GDD) according to Equation 4: In this equation Tmax: maximum daily temperature, Tmin: minimum daily temperature, Tb: temperature of the plant, which was considered to indigo 10.27 °C (6). Fitting equations and drawing diagrams were performed using Sigma Plot 10 version. Analysis of variance and correlation between traits were performed using SAS software and means were compared using LSD test at the 5% level.
Results showed that (Figure 2a and Table 2) the earliest planting date (18 June) increased total dry matter and crop growth rate about 4.41 and 3.59 folds compared to third planting date (18 July), respectively. In addition, the highest GDD was recorded for the first sowing date (18 June). The results showed that the fastest (38.34) and the lowest (12.37) growing rate was related to 18 June and 18 July planting dates, respectively (Table 3). Gupta (10) also stated that there was a significant correlation between sowing time and plant biological yield, as with delay in sowing date plant dry weight has been decreased. Mean comparison results showed that the lowest plant height was obtained at the early planting date (18 June) and the lowest of it was seen in the late planting date (18 July) (Figure 5 B). In the first planting date (18 June), biological yield increased 47.27% compared to the later planting date (18 July). In third sowing date biological yield decreased significantly than first and second planting dates (Figure 5 A). Zhelgazkov et al. (21) on Coriandrum sativum L. showed that the earliest cultivation increased the length of effective growth period and finally caused an increase in fruit and biological yield. The reason for reduction of biological yield in delayed cultivation in addition to shortening of growth season is related to coincidence of vegetative and reproduction period with summer heat which resulted in severe reduction in the stem height, leaf dry matter and finally decreasing biological yield. This result is in agreement with findings of Kacurik (14); he stated that the height, fresh and dry flowers of the chamomile was reduced with delay in planting date.
In this study, the highest plant height, leaf dry weight and biological yield, was observed in 18 June sowing date. According to our results may be both day long and especially temperatures during reproductive growth, flowering and maturity are the limiting factors in above ground biomass formation. Based on our results, sowing dates of 18 June was the best planting date for indigo plant in Shahrood region.

To evaluate the effect of corn،s various planting method on weed control، grain yield and growth indices of corn (Single cross 704)، a study was conducted in 2006 at the research field of Weed Research Department، Iranian Plant Protection Research Institute، using randomized complete block design with 3 replications. Treatments were foure methods of corn planting (one line on furrows، tow lines on furrows، one line in the furrows، and one line in the furrows and then replacement of furrow by row). The results of the experiment show that forth planting method (one line in the furrows and then replacement of furrow by row) had highest LAI، TDM، RGR، CGR and NAR and grain yield compared with the other planting method. The results of the experiment show that 4th planting method produced the highest grain yield compared with the other planting method. Furthermore The forth planting method had the least weed biomass and weed density than the other planting methods.

Understanding the variation of kernel number per unit area (KNO) is an important factor in respect yield and in identifying opportunities to increase potential yield. Some crop models are for dependence on kernel number prediction to yield simulation. In order to quantify the relationship between kernel number per unit area and influencing parameters (Environment and non-environment-based factors), compound analysis with randomized complete block design was conducted including four replications. This experiment was done at the Gorgan University of Agricultural Sciences Research Farm in 2005. The treatments were five different sowing dates (14 December, 20 Jan, 20 Feb, 20 March, 16 Apr) and four wheat variations (Kohdasht, Shirudi, Tajan, Zagros). Considering results of correlation coefficients, kernel number per unit area appeared to have the best relation with mean temperature, but Non-linear models fitting indicated that the highest R2 and the lowest CV belonged to stem dry matter at anthesis. Fitted model showed that 95% of kernel numbers are formed when stem dry matter is around 747 g.