جستجوی مقالات مرتبط با کلیدواژه « رسیدگی فیزیولوژیکی » در نشریات گروه « زراعت »

This study aimed to investigate the effect of sowing date and enviromental factors during different growth stages on some phenological characterisitcs and grain yield of commercial bread wheat cultivars. The experiment was carried out as split-plot arrangements in randomized complete block design with three replications at the Darab reaesrch field station in 2018-19 and 2019-20 cropping cycles. Five sowing dates: October 27, 11, and November 26, December 11, and 26, were assigned to the main plots. Five commercial wheat cultivars: Mehregan, Barat, Khalil, Sarang, and Setareh, were randomized in the subplots. Results showed that the late maturity cultivars, Khalil and Brat, had higher grain yield in earlier sowing dates. Early maturity cultivars, Setareh and Mehregan, had less yield reduction in later sowing dates. The highest and lowest mean grain yield obtained from November 11 (6934 Kg ha-1) and December 26 (5775 kg ha-1), respectively. Number of days and required growing degree-days (GDD) decreased with delaying sowing date. The decrease of required GDD to reach commencement of stem elongation, anthesis and maturity stages from the first to fifth sowing date was 181, 282 and 528 GDD, respectively. Simultaneous effect of weather variables and sowing date on some characteristics revealed that the first two components explained approximately 41% of total variation. Results showed that temperature was the most important factor controlling the phenological stages duration. Despite the importance of temperature, changes in sowing date can alter the required GDD for phenological stages due to other environmental factors. In general, the results of this study can provide an insight into bread wheat cultivars responses to different climatic conditions and development of new bread wheat cultivars adapted to target environments.

The most important determining factor in sugar beet root yield is seed quality. Seeds with germination percentage are lower; the germination is slow and non-uniform, will produce plants that initial growth is slow. According to various studies indicate that harvest time is an important factor influencing the quality of sugar beet seed. In the early harvest of sugar beet seed plants, germination and seed vigor is low and late harvest also led to an increase in losses due to seed loss. However, in the specified number of days after the first flowering, germination percentage in various cultivars may be significantly different. Like other crops, harvest timing is essential for achieving high quality seeds of sugar beet. Therefore, this study was to evaluate changes in seed quality during development and ripening in cytoplasmic male sterile (CMS) lines of sugar beet and determine a stage of development where maximum seed quality was done. This study was conducted in Ardabil Agricultural Research Station (Alarough) in 2012 and based on a Completely Randomized Block Design. The experimental treatments were five promising diploid cytoplasmic male sterile (CMS) lines (7112×SB36, SB37×28874, 7112×436, 419×SB36 and 261×231) of sugar beet. Each plot consists of eight lines planting and hybrid varieties were sown in strips in female: male ratio was 6: 2. To evaluate changes in the quality of sugar beet seed, 5 plants in each plot in the flowering stage were symptomatic and from 50 percent flowering until the end of the growing period, growing seeds were harvested at intervals of 7-5 days. After harvesting and calculate fresh and dry weight of fruits, was carried out germination test, accelerated aging and electrical conductivity. Results indicated that there were significant differences among different female parent in respect to maximum seed dry weight. Needed Degree days (GDD) to attain the maximum seed weight after 50% flowering was 507.5, 563.3, 459.3, 499.7 and 492.7 for 7112×SB36, SB37×28874, 7112×436, 419× SB36 and 261× 231 lines, respectively. At the corresponding dates, the seed moisture content was 52.3, 40.8, 52.6, 44.4 and 42.5%, respectively. The maximum seed quality (maximum germination) for SB37×28874 and 261×231 occurred before, but for 7112×SB36, 7112×436 and 419×SB36 after the physiological maturity. To achieve high quality seeds in sugar beet, harvesting must be done at 480-580 degree-days after 50% flowering. At this time, the moisture content of fruits was in the range of 40-52% and the fruits were red-colored.

In order to evaluate the interaction of both treatments of deficit irrigation during growth duration and irrigation-cut in some growth stages, on reserve materials redistribution, current photosynthesis and its relation with yield of grain maize this research was conducted as factorial in randomized complete blocks design with three replications at research field of Islamic Azad University, Sciences and Research Branch of Khuzestan during 2007-2008 and 2008-2009 two cropping years. The research treatments were consisted of deficit irrigation at three levels (providing 100, 80, 60 percent of full irrigation requirement was measured for corn) and irrigation-cut at different growth stages at five levels (without irrigation-cut during growth duration (control), one time irrigation-cut at eight-leaf, twelve-leaf ,the pollination and milky stage). Irrigation treatments applied at four to five leaf stages and continued until ten days before plant physiological maturity. The results of this research showed that the effect of deficit irrigation and irrigation-cut treatments on the amount, contribution and efficiency of current photosynthesis and redistribution was significant. With increasing intensifying deficit irrigation, current photosynthesis contribution decreased instead redistribution contribution in grain filling increased. In treatment of providing 100 percent plant irrigation requirement, the highest and lowest contribution of current photosynthesis belonged to treatments without irrigation-cut tension and lack of irrigation at flowering stage by the average of 81 and 41 percent, respectively.

New sunflower hybrids were evaluated for their suitability for second cropping system in temperate-cold regions of Kermanshah Province in Iran. A split plot arrangement in randomized complete block design with three replications was used in 2010 to 2011. Planting dates including: June 11، June 26 and July 11 and sunflower hybrids including: Azargol، Farrokh and SHF-81-90 were assigned to main plots and sub- plots، respectively. Results showed that effect of planting date was signification on agronomic traits such as seed yield، days to physiological maturity and 1000 seed weight. Seed yield reduced with delay in planting date as the first and third planting dates had the highest and lowest seed yield with 4199 and 3118 kg ha-1، respectively. Hybrids were also significantly different for most of the traits. New hybrid Farrokh had the highest seed yield with 3940 kg ha-1 followed by SHF-81-90 and Azargol with 3788 and 3459 kg ha-1، respectively. Farrokh with 95 days to physiological maturity was more suitable for second cropping systems. In conclusion، new early maturity sunflower hybrid Farrokh is recommended for second cropping systems in temperate-cold regions of Kermanshah Province in Iran.

To study the variation in developmental stages and its relationship with grain yield and its components, this reasecrh was conducted in three successive cropping seasons (2000 – 2003) in experimental field stations of Seed and plant Improvement Institute, Karaj, Iran. Twenty bread wheat cultivars adapted to four different agro-climatic zones (Cold and Tempearte Cold; Tempearte; Southern Warm Dry; and Northern Warm and Humid) were studied-using randomized complete block design with three replications under field conditions in Karaj, Iran. Results revealed that bread wheat cultivars were significantly different in term of bilological yield, grain yield and yield comonents. These variations could be aattributed with genetic differences and adaptation to different agro-climatic zones as well as variation in their phonology particularly duration of differnt developmental stages. Cultivars adapted to cold and tempearte cold and temperate zones produced greater biological yield (17798 and 17662 Kg ha-1, respectively), and grain yield (7236 and 7229 kg ha-1, respectively). There was not considerable differences among different groups of cultivars for HI (39.3–42.5%). Results of correlation analysis between grain yield and its components with different phonological developmental stages also indicated that relationship between spike No. m-2 and was positively correlated with with the duration from Sowing to Terminal Spikelet stage, however, it was negatively associated with duration of rapid stem elongation (Terminal Spikelet to Anthesis) stage. The relationship between 1000 grain weight (TGW) and the duration of vegetative (Sowing to Double ridge) and pre-anthesis reproductive (Sowing to Anthesis) stages was also negative. It is concluded that studies of phonological development variations and its relationship with grain yield and yield components over years and locations can be used to expalain, to graet extent, the the adaption of different bread wheat cultivars to different agro-climatic conditions as well as variation in their grain yield.

Wheat crop development is defined as a sequence of phenological events controlled by environmental factors as well as genetics determining differentiation in plant morphology and functions of some organs. It commences with germination and terminates with physiological maturity in each crop life-cycle and can be divided into different distinguishable stages/phases. To study the phenology of bread wheat genotypes, 20 different cultivarsor promising lines adapted in four different agro-climatic (cold and temperate cold temperate southern warm and dry northern warm and humid) zones were studied, using a randomized complete block design with three replications, under field conditions in Karaj, during three successive cropping seasons (2000-2003). The results revealed that genotypes were significantly different in the duration of different phenological stages. Genotypes associated with cold and temperate cold zone were of longer crop life-cycle which was mainly due to differences in the duration of their vegetative phase (Sowing to Double Ridge). The results also indicated that in all four agro-climatic zones, developmental phases including Sowing to Double Ridge (S-DR), Double Ridge to Terminal Spikelets (DR-TS), Terminal Spikelets to Anthesis (TS-Anth) and Anthesis to Physiological Maturity explained 0.39%, 68%, 0.63% and 0.52% of variations in grain yield, respectively. Correlation studies between different developmental stages and yield components also indicated that, in all four agro-climatic zones, the number of spikes m-2 was positively correlated with the duration from Sowing to Terminal Spikelets, however, it was negatively correlated with the duration from Terminal Spikelets to Anthesis. The relationship between Thousand Kernel Weight (TKW) and the duration of S-DR and S-Anth was negative. It is concluded that phenlogical studies can be utilized to study the adaptation of different genotypes to different agro-ecological zones and to explain the variation in grain yield and its components.