مجله تولید گیاهان زراعی
سال چهارم شماره 3 (پاییز 1390)

In order to investigation of irrigation management and plant density effects on water productivity of rice, a field experiment was conducted in the Rice Research Institute of Iran (Rasht) during 2001 and 2002. The study was carried out in a split plot design with four different irrigation regimes as main plots and three plant densities as subplots. In this experiment, ORYZA2000 model was used to quantify water productivity, and water balance components of alternate for irrigation and plant density interactions in rice. Evaluation simulated and measured yield by adjusted coefficient of correlation; T test of means; and by absolute and normalized root mean square errors (RMSE). Results showed that the yield was simulated with an RMSE of 150–182 kg ha-1 and a normalized RMSE of 6%. In order to model the various water productivity components, ORYZA2000 model was used. Using the actual yield and simulated water balance (ORYZA2000), the calculated average WPET was lower than the average WPT: 35%. The results showed that the irrigation by 75% evaporation from pan evaporation and 20cm×20cm plant density is the optimum irrigation method and crop density management.

In order to study the effects of integrated application of bio- and chemical fertilizers and application method of biofertilizer on the yield and yield components of maize (Zea mays L.), an experiment was conducted in 2008 in Shushtar in a factorial arrangement with completely randomized block design with three replicates. Treatments were integrated application of biological and chemical fertilizers in four levels and biofertilizer application method in three levels. Results showed that the highest grain yield was obtained by application of biofertilizers + 50% chemical fertilizer (11.8 t/ha). The greatest and lowest harvest indices were recorded in chemical (0.59) and biofertilizer (0.47) treatments, respectively. Number of grain per row and row per ear had not significant differences in integrated and chemical treatments. Methods of biofertilizer application had not significant effect on maize yield and yield components. Results showed that biofertilizers increased P, K as well as other micro elements availability rather N fixation. Results revealed although replacing chemical fertilizers by biofertilizers reduced maize yield, integrated application of these sources produced highest grain yield as well as reduced substantially consumption of chemical fertilizer.

Mulches often use for weed control, hold soil moisture, decrease soil temperature, soil fertility, soil conservation, soil against rain and soil quality in organic farming. A field experiment was conducted to evaluate the effect of different wheat residue and sunflower densities on sunflower growth and yield during 2007 growing season at the research field of Birjand University. The experimental design was randomized complete block in factorial with three replications. The experiment treatments were wheat residue at the rates of 0, 1250, 2500, 3750, 5000 Kg.ha-1 and burning residue and three levels of sunflower density (50000, 70000 and 90000 Plant.ha-1). Results showed that effect of wheat residue and sunflower density levels was significant on sunflower biomass, height and grain yield. With increasing wheat residue and sunflower density, sunflower biomass, height and yield increased significantly. Results showed that by increasing wheat residue, sunflower biomass increased 61.77, 52.08 and 42.71% more than control respectively in 3, 6 and 9 weeks after planting. In this three weeks, with increasing density, sunflower height increased 66.82, 49.48 and 50.16%, respectively. Also, sunflower grain yield increased 29.86 and 31.73 % with increasing wheat residue and plant density, respectively. Results showed that maximum sunflower growth and yield were obtained by using of 2500 Kg.ha-1 wheat residues and the highest density of sunflower.

Growth analysis is a valuable method in the quantitative analysis of crop growth, development and crop production. There are many regression models to describe the sigmoid growth patterns. By considering that, the parameters of nonlinear regression models have physiological meanings, they are preferable relation to linear regression models. The aim of this study was to collect and evaluate the high visibility non-linear regression models in the growth analysis studies (Logistic, Gompertz, Richards, Weibull, Truncated Expolinear, Symetrical Expolinear and two kinds of Beta model to describe the biomass accumulation, and Logistic and Beta models to describe the leaf area index variation patterns). An experiment was conducted using 7 wheat cultivars (Arya, Darya, Kuhdasht, Shiroudi, Tajan, Taro and Zagros) in 2 conditions, irrigated and rainfed, in randomized complete block design with 4 replications in 2008-2009. All models were fitted to the dry matter and LAI data of two cultivars (Arya and Zagros). Results shoed that all of the used models at this study described well the variation pattern of dry matter accumulation and LAI by time (day after planting). And these models can be used in the growth analysis studies.

This experiment was conducted to evaluate rate and duration of grain filling among old, modern and promising rice cultivars under different nitrogen levels in fields of Sari Agricultural Sciences and Natural Resources University, during 2008. Two factors consisted of different urea fertilizer (0, 100 and 200 Kg ha-1) as main plot and four promising lines (Jelodar, Partou, Danesh and Jahesh), 2 old cultivars (Tarom Mahalli and Tarom Deilamani) and improved cultivar (Ghaem1) as sub plot were examined using a split plot design based on randomized complete block design with 3 replications. Among all mentioned traits, in nitrogen levels, flag leaf area, chlorophyll content (a+b), days to 50 percent of flowering, paddy yield and cultivars except for effective grain filling duration showed significant differences. Grain filling in different fertilizer treatment had nearly similar pattern (third degree equation). Grain filling and maximum individual grain weight respond differently to different nitrogen fertilizer rates. The highest and lowest grain filling rates were belonged to Partou and Jelodar with no fertilizer application. Among genotypes, Danesh with 6.72 Kg ha-1 had the maximum paddy yield. Orthogonal contrast for three groups of genotypes indicated that in terms of chlorophyll content (a+b) and grain filling rate, old cultivars showed higher rate compared to modern cultivars used in this experiment (Ghaem1).

In the present study, effects of iron excess treatments (0, 250, 500 mg L-1) were evaluated in four rice varieties including Shafagh, Khazar, Hashemi and Sadri in pot condition. Afterward, effects of iron excess (10 and 250 mg l-1) were further investigated in the most resistant variety (Shafagh) in sand culture with Yoshida nutrient solution. This experiment was arranged as factorial in RCBD with three replications in greenhouse condition. The results of soil experiments indicated that 250 and 500 mg l-1 treatments of iron reduced plant growth and relative water content in all varieties. The highest and the lowest growth reduction under iron toxicity were observed in Khazar and Shafagh varieties, respectively. Iron accumulation in roots was higher in iron excess treatments in compare to shoots. The potassium concentration decreased in all varieties, however, the lowest decrease rate under stress condition was exhibited by Shafagh variety. The results of sand culture experiments of Shafagh variety indicated that oxidative stress due to 250 mg L-1 iron treatment caused reduction of chlorophyll content and consequently proteins, soluble sugar decreased probably by photosynthesis decline. Increase of amino acids content in plants fed with high iron supply is may be result lower protein synthesis or higher protein degradation.

To evaluate the effects of organic, chemical and integrated fertilizers on yield and yield components of turnip (Brassica rapa) an experiment was conducted in research farm of college of agriculture, University of Tehran, Iran, during 2009 - 2010 growing season. The treatments were arranged as randomized complete blocks design with three replications and fifteen different fertilization systems. The results showed that the highest root (tuber) dry matter production (836.2 kg.ha-1) was achieved by application of Zeoponix+Vermicompost+25% chemical fertilizer while the highest shoot dry matter was produced by Zeoponix + 50% chemical fertilizer and Vermicompost+biological fertilizer+ 25% chemical fertilizer treatments. The highest total forage production (shoot+ tuber) was observed in both Zeoponix+ 50% chemical fertilizer (17613.3 kg.ha-1) and Vermicompost + biological fertilizer + 25% chemical fertilizer treatments (16000 kg.ha-1) which out produced the control treatments by 106 and 87%, respectively. Integrated application of organic and chemical fertilizers had a synergetic effect on turnip forage production. Application of integrated fertiliztion system had more positive effect on forage yield compared to individual application of different fertilizers. The results of this experiment also revealed that organic fertilizers were more effective on yield increment of forage turnip than chemical fertilizers.

In order to study drought tolerance indices and to introduce tolerant maize hybrids in drought conditions, an experiment was conducted at the experimental field of Seed and Plant Improvement Institute, in 2009. The experiment was carried out using split-plot in a randomized complete block design (CRBD) with three replications. The main plots consisted of three levels of irrigation regimes (irrigation after 70, 100 and 130 mm cumulative evaporation from evaporation pan class A) and sub-plots included 14 new corn hybrids. Based on kernel yield of hybrids in normal and stress conditions, mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), tolerance (TOL), yield index (YI), yield stability index (YSI), stress susceptibility index (SSI) trait and change (%) attributes were calculated. The results showed that, in addition to significant correlation under normal and mild drought stress conditions MP, GMP, STI were determined as the best indices. Under normal and water deficit stress TOL and SSI were the best indices for introduce drought tolerant maize hybrids. The KSC700, KLM76004/3-2-1-1-1-1-1-1×K3545/6 and K47/2-2-1-2-2-1-1-1×K3544/1hybrids also identified as tolerant hybrids under drought stress conditions.

An experiment with randomized complete block design with 3 replications was carried out in the Rice Research Institute of Iran, Rasht, during 2008 to study the effect of supplement foliar application of nitrogen (5% N) and potassium (3% K2O) at different growth stages (maximum tillering stage, booting stage, and both of them) on grain quality and nitrogen efficiency of hybrid rice, c.v. Bahar-1. Results showed that foliar application of nitrogen and potassium significantly increased the grain yield (10256.3 Kg ha-1), by 56% compared with control treatment. The highest amount of grain protein (11.6%) was related to foliar application of nitrogen in both maximum tillering and booting stages when compared with control. Also, the results showed that foliar fertilization at different growth stages had not significant effects on nitrogen utilization efficiency and nitrogen harvest index. Among cooking quality and milling factors, gelatinization temperature, chalky and broken rice percentage were not affected by foliar fertilization,significantly, while percentage of grain amylose, gel consistency and percent of hale rice significantly affected. Overall, it could be concluding that hybrid rice, cv. Bahar-1, has mediocre cooking quality, and foliar fertilization improved its milling performance.

To better understanding of drought resistance features including tolerance to chemical desiccation and transient photosynthesis under soil moisture stress in triticale in comparison with wheat and barley, an experiment was conducted during year 2009-10 in Grizeh agricultural research station located in Sanandaj. Effect of three soil moisture regimes including irrigation in soil water potential of -3 bar, -10 bar and no irrigation on eight cereal genotypes including four triticale lines, three bread wheat and one barley cultivars were studied. To stop the current photosynthesis and to assess the grain weight stability of genotypes under stress conditions, a part of control plots (irrigation in -3 bar), was sprayed by sodium chlorate 1%. Results showed that sodium chlorate reduced kernel weight and incited stem reserve mobilization rather than control by 51 and 75%, respectively. Generally, the kernel weights of triticale in both sprayed and stress conditions were higher than those of wheat and barley. By reducing transient photosynthesis under no irrigation treatment, the stem reserve mobilization was encouraged which was more pronounced for triticale rather than barley and wheat. Also under stress condition both stomatal and non stomatal factors had important role in the limitation of net photosynthetic rate.

In this research for study the effects of nitrogen fertilizer on yield and yield components of current rice cultivars was an experiment as factorial in RCBD with three replications where conducted during 2009 year in two locations (Rice Research Institute, Rasht, and Rudsar, East of Guilan). Factors were cultivars (Khazar, Ali Kazemi and Hashemi), and nitrogen fertilizer levels (0, 30, 60, and 90 Kg N/ha). Results of Combined analysis of data indicated that the grain yield and final biomass was significantly affected by location, cultivar and N fertilizer. Khazar (3943 Kg/ha) and Ali-Kazemi (3417 Kg/ha) were showed the highest grain yield among cultivars. The highest grain yield (3980 Kg/ha) was obtained from Rudsar location. Also, Results indicated that, with increasing N fertilizer application grain yield, was increased significantly in compared with control treatment (without nitrogen fertilizer application).