CROP PHYSIOLOGY
Year:2009 | Volume:1 | Issue:3|Papers Count:12

At the start of growing season, nitrate concentration in soil is high. Therefore, during the autumn, organic N will be converted to inorganic N, and at this time, N fertilizer is added to soil. The optimum use of this amount of nitrogen will be useful. There fore, some wheat cultivars were studied in a serie of experiment using a hydroponic culture system for the nitrate uptake and analysis. Seedlings were grown at two rates of nitrates (0 and 1.0 mm) and were compared in a 26 day growth period. Results indicated that a significant difference exists between wheat cultivars for the nitrate uptake. Atila and yavarous cultivars absorbing higher amount of nitrate produced larger seedlings, compared to the falat, star and sarasari 11 cultivars which produced smaller seedling and took up lower amounts of nitrate. According to difference among cultivars for seedling vigor, the results indicated that the first group including Atila, Chenalter, Sarasari 20, Yavarous, and Sarasari 11 had more physiological efficiency in nitrate consumption. According to absorbed nitrate, the amount of produced dry matter by the cultivars of this group was higher. On the whole we can say that genetic variation in nitrate absorption among wheat cultivars is due to a modification in plant size and specifically the root system.

In order to investigate and determinate the best date of cultivation of dual purpose barley under treatment of fertilizer, An specific experiment during years of 2000-2001 was accomplished in experimental farm of Ahvaz Azad University.The experiment was carried out in the form of compound split-plot in a factorial experiment in a completely randomized block design and in four replications. The levels of date of cultivation consist of 12th October, 1th November and 21th November and various amount of nitrogen fertilizer consist of usage of 90 Kg (control) and 120 Kg pure nitrogen in hectare in the main plot (in the form of factorial) and number of cutting consist of: non-cutting (control), cutting for one-time and two-time cutting that were put in subplots.Obtained results from this experiment showed that with delaying in cultivation, the economical yield of grain, biological yield and lodging degree, decreased and yield of green provender increased. In addition, obtained results showed that with increasing nitrogen fertilizer from 90-120 Kg per hectare, the biological yield and lodging degree increased, but harvest index decreased. On the other hand with increasing the time of cutting, the harvest index and yield of green provender increased but biological yield and extremely height of plant decreased.

Achieving to high yield in wheat is possible through adjusting growing and reproductive development processes of plant with favorite environmental conditions via selecting proper planting dates for high yield cultivars. The purpose of this study is to consider planting date effect on the yield and its components in late maturity wheat cultivars. This study was accomplished in the form of split plots in a completely randomized block design with three replications in Ahvaz farming research station in farming year 2008-09. The main factor included three planting dates (10/12, 10/22 and 11/01 and the secondary included 10 wheat genotypes (chamran, star, akbari, sistan, bam, bahar, pishtaz, karkhe and two s-78-11 and m- 83-17 lines). The results indicated that seed yield increased, due to delaying in planting date in comparison with first planting date. So that maximum seed yield of 4146 kg per hactare belonged to the third planting date. In interaction of planting date and genotype, the third line83-17 - M assigned maximum mean to itself in characteristics of seed yield, seed numbers per spike, and spike number per surface unit. Seed yield of line M-83-17 in the third planting date was 5135 kg per hectare.

Seed priming is a technique through which the seeds before being placed in a context of culture, obtain ability of germination physiologically and biochemically. This causes lot of physiological and biological changes in seeds and their generated plants, so the results of this performance, will be visible in germination, initial plant establishment, earliness, and the increasing of product in quality and quantity. In this study the effect of hydropriming on (seed preparation) seeds was studied on germination and growth of sweet sorghum varieties Sofra in salinity conditions, the experiment was accomplished in a factorial experiment in a completely randomized design with three replications in the Faculty of Agriculture, Azad University of Ahvaz. Factors tested, included three levels (No Prime), 12 and 24 hours Prime seeds with distilled water and five levels of salinity, the zero (control), 50, 100, 150 and 200 mM sodium chloride salt. Analysis of variance indicated that seed germination of sweet sorghum has been affected by different levels of salinity, and the percentage of germination was reduced with the increase of salinity levels. The results indicated that in the highest level of salinity, prime seeds had higher percentage in germination in comparison with other seeds. High salt concentrations (150 and 200 mM L) increased the required average germination time. High levels of salinity reduced root and shoot length. With increasing salinity levels, root and shoot dry weight decreased significantly, and although seeds hydropriming caused a moderate stress, but this reduction was not significantstatistically.

Final grain weight a component of grain yield in wheat (Triticum sativa L), is dependent on the rate and duration of the grain filling process. A thorough understanding of the grain filling process maybe helpful in attempts to breed for increased yield and early maturity in wheat. This study was conducted to evaluated ten wheat cultivars, at Research Farm, College of Agriculture, Islamic Azad University Shushtar Unit, in 2004-5. A randomized complete block design with four replications was conducted. The logistic curve provided a good fit to the grain filling data obtained in this study. Rate and duration of grain filling were obtained from the fitted curve. Cultivars differed significantly in grain filling rate, grain filling duration and final grain weight. Correlation coefficient between final grain weight and grain filling rate was highly positive. But the phenotypic correlation between the grain filling rate and grain filling duration was not significant and suggested that there was no genetic association between these characteristics. Results suggested that it should be possible to simultaneously improve grain filling rate and final grain weight without lengthening duration of grain filling. Since the result of linear and logistic models justified more meaningfully the physiological processes of the plant, it was recommended to use these equations in estimation of rate and duration of grain filling.

The effect of planting date and cultivar on yield and yield components of corn to different groups split plot with repeated toxin sink area was conducted in 2009. Results showed that planting date on Thousand seed weight, number of seeds in rows and grain yield was significant at 1% statistically. The number of rows of grain maize wasn’ t significant and wasn’ t affected by planting date. The best planting date was at Khordad 31st with the yield of 17.88 per hectare. The effect of different hybrids on yield was significant and the highest yield was associated with hybrid S.C 500 with the yield of 14.71 ton per hectare. The cultivars S. C 700, S. C647, S.C400, S.C704 andD.C370 had less yield compared with the best hybrid including 5.6, 8.1, 8.2, 10.4, and 18.3, respectively.According to obtained results from the interaction between planting date and hybrid, the most grain yield was in hybrid S700 in planting date Khordad 31st.

In order to evaluate the competitive effects of Wild oat with spring Wheat under different Nitrogen levels, an experiment was conducted in 2008-09 in the research farm of Ahvaz Azad university. The experimentwasperformed in split– plot and in randomized complete block design with three replications in additive series.Main plots received Nitrogen fertilizer levels (90, 150, 210 kg net nitrogen in per hectare) and sub – plots included Wild oat at four densities (0, 25, 50, 75 plants/m2).Results showed that increasing Wild oat density led to decreased biological and economical yield of Wheat, that economic yield reduction was greater than biological yield. In control plot, increasing usage of Nitrogen caused an increase in grain yield of Wheat; however at the present of Wild oat, increasing Nitrogen application led to increase the damages of Wild oat on grain yield of Wheat. Seed production of Wild oat was 38.69, 50.04 and 56.06 million seeds per hectare in low, optimum and high Nitrogen levels respectively. On the other hand, Nitrogen rates had a positive and significant effect on Wild oat fecundity.

Forage sorghum (Sorghum bicolor L. var Sugar graze) has a high forage yield and multi-cut in khouzestan condition. In order to determinate the cutting date of sugar graze, an experiment was carried out at the research farm of Khouzestan Agricultural and Natural Resources in Research Center from 2006 to 2007. This research was conducted in the form of randomized complete block design, with 4 replications. Treatments were 17 dates of cutting. The first treatment (cutting) was done after plant establishment. The other cuttings were done in 10 days intervals. Results showed that there was significant difference among dates of cutting. Study of growth analysis such as NAR, CGR and RGR revealed that, till 140 days after planting, amount of these indices were zero and then negative. According to these results, the first date of cutting must be before this date. The other results expressed that treatment of 100 days after planting caused the highest dry forage yield. Accordingly, this study recommended that date of first cutting, must be done 100 days after planting or beginning of flowering.