Relationship between GRAIN FILLING RATE, GRAIN FILLING duration, yield components and other physiological traits of rice was investigated in 93 genotypes of rice at Rice Research Institute of Iran (Rasht, Iran) during the growing season of 2001-2002. The experiment was performed without any statistical design. Panicles of main stem were tagged and taken at 3- day intervals during the GRAIN FILLING period. A cubic polynomial model was used to fit the GRAIN dry weight data (mean of R2= 0.98 for all genotypes) and the GRAIN FILLING RATE and duration estimated for the genotypes. Traits related to sink capacity such as GRAIN weight, GRAIN size and GRAIN number per panicle correlated with GRAIN FILLING RATE but source capacity- related traits except chlorophyll content of flag leaf and secondary leaf did not correlate with GRAIN FILLING RATE. Stepwise regression showed that final GRAIN weight, GRAIN FILLING duration and flag leaf angle contributed to GRAIN FILLING RATE, however, path analysis showed that only final GRAIN weight and GRAIN FILLING duration had the greatest effect on GRAIN FILLING RATE. The results of stepwise regression irrespective of final GRAIN weight showed that chlorophyll content of flag leaf, GRAIN width, GRAIN FILLING duration and GRAIN length contributed to GRAIN FILLING RATE. Path analysis results showed that the final GRAIN weight had the greatest direct positive effect on GRAIN FILLING RATE, while GRAIN FILLING duration had negative effect on GRAIN FILLING RATE.

In order to study two GRAINs FILLING characteristics (specific effective GRAIN FILLING period and effective GRAIN FILLING RATE) to improvement of GRAIN yield this study was conducted during 1999 and 2000 growing season in Koohdasht dry land Research Station in Lorestan Province. An experiment using complete randomized block design which ten rain-fed wheat (Triticum aestivum L.) genotyps treatments with four replications was used. Also, to determine correlation coefficients between triats, parameters were measured consist of GRAIN yield, 1000 Kernel weight, harvest index, biological yield, straw yield, effective GRAIN FILLING RATE, test weight. Results showed that a significant positive correlation between GRAIN yield with 1000 Kernel weight, Harvest index, biological yield, straw yield, effective GRAIN FILLING RATE test weight and with number of days, to steming was a negative significant correlation. Results of the growth GRAIN process indicated that overall, at the end the linear of (Tr 8010200, Zagross) No. 4 and No.10 genotypes were the most final GRAIN weight (40mg) and genotypes (Pik/opatacm, Maya 74 "s") No. 2 and No. 7 were the least final weight GRAIN with 32 mg. Effective GRAIN FILLING period were among genotypes 18.39 to 25.03 days. The most effective GRAIN-FILLING period was 25 days related to No.10 (Zagross) genotype and the least No. 7 (Maya 74 "s") genotype with 19 days. Effective GRAIN FILLING RATE among genotypes were 1.43 to 1.74 mg.days-1. The most and the least effective GRAIN-FILLING RATE was for No. 2 (pik/opata) and NoA (Tr8010200) respectively. Between effective GRAIN FILLING RATE and period were significant negative correlation (r=-46 %**).

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.

In order to investigate the effects of temperature and radiation on RATE and duration of GRAIN FILLING and final GRAIN weight in rice cultivars, a split plot experiment based on randomized complete block design with three replications was conducted at different transplanting times at the research field of University of Guilan, Rasht, Iran in 2013. Factors were: transplanting dates in main plots (5 May, 20 May and 5 June) and rice cultivars (Hashemi, Ali Kazemi, Sangejo, Khazar, Dorfak and Gouhar) in sub plots. The greatest GRAIN weight (31.9 mg) was obtained in Gouhar at 20 May and the smallest GRAIN weight (20.4 mg) was observed in Sangejo at 5 June transplanting dates. The longest effective FILLING period (32.9 days) was achieved in Gouhar at 5 May transplanting date and the shortest GRAIN FILLING duration (13.9 days) was obtained in Hashemi. The greatest GRAIN FILLING RATE (1.62 mg day-1) was obtained in the Hashemi and the smallest RATE (0.92 mg day-1) was observed in Gouhar. Significant correlations were observed between cumulative temperature and radiation with final GRAIN weight (R = 0.689). There were significant and positive correlations between the cumulative temperature and irradiance with GRAIN FILLING duration, in contrary to negative correlations with GRAIN FILLING RATE and GRAIN FILLING period. The results of this experiment showed that the GRAIN FILLING duration plays a greater role, than GRAIN FILLING RATE, in determination of the GRAIN weight. It could be concluded that an early transplanting (5 May) brings about favorable temperature and radiation conditions for an appropriate GRAIN FILLING period and a greater final GRAIN weight.

Eleven wheat cultivars were evaluated at 10-day intervals, beginning from anthesis, under irrigated and drought stress conditions during 2006-2007. The effects of irrigation, genotype and date of harvest were significant for most of the studied characters. Water deficit decreased pre-and post-anthesis assimilation RATE, GRAIN weight per spike, GRAIN number per spike and 1000 GRAIN weight about 5.7, 24.5, 21.2, 15.7 and 6.4 %, respectively. Mobilization, mobilization efficiency and contribution of pre-anthesis assimilates to kernels were considerably increased under drought stress condition. GRAIN weight, GRAIN growth RATE and contribution of current assimilates to GRAIN FILLING decreased under drought stress about 7.18, 22.1 and 29.6 %, respectively. However, the effective GRAIN FILLING period was considerably increased in the stressed plants. GRAIN FILLING RATE was correlated with the accumulation of dry matter at maturity, GRAIN weight per spike and GRAIN number per spike in the irrigated and drought stressed environments (r=0.87** and 0.53, r=0.87** and r=0.62*, r=0.75* and r=0.63*, respectively). A negative correlation was found between effective GRAIN FILLING period and GRAIN yield/spike under irrigation (r =-0.65*) and drought stress (r =-0.76**) conditions. Furthermore, positive correlations between GRAIN FILLING RATE and GRAIN yield were obtained in the irrigated and drought stressed environments (r = 0.87** and r = 0.62*, respectively). It seems that accumulation of pre-anthesis assimilates (mainly under drought stress), short effective GRAIN FILLING period and high GRAIN FILLING RATE are major factors for producing higher GRAIN yield in wheat under both irrigated and drought  stress conditions.

The yield of maize in Iran is very low as compared to other maize producing countries. One of the most important effective factors is non application of optimal plant population per hectare and maize hybrids differ in their response to plant density. In order to study the effect of different plant densities on yield, RATE and effective GRAIN FILLING period in maize hybrids, a factorial experiment based on randomized complete block design with three replications was conducted in 2007 at the Research Farm of the Faculty of Agriculture Mohaghegh Ardabili University. Experimental treatments were: maize hybrids in three levels (SC-404, DC-370, SC-504) with different plant densities (8, 10 and 12 plants.m-2). The results showed that yield and yield attributes characters (except of the number of GRAINs rows) varied significantly due to the variation in population densities. The number of kernel per ear and number of GRAINs per ear row increased with increasing plant density. The highest GRAIN yield was obtained from 10 plant.m-2 density. Response of maize hybrids wasn’t the same for plant densities. The highest GRAIN yield belonged to SC-504 hybrid and the least was in DC-370 hybrid. A two part linear model were used to quantifying the GRAIN FILLING parameters. Cultivars and plant densities affected all GRAIN FILLING parameters significantly.Maximum kernel weight, RATE and effective GRAIN FILLING period was obtained in low plant densities.Means of comparisons showed that maximum of kernel weight (0.35 mg) and effective GRAIN FILLING period were obtained in SC-504 hybrid×8 plants.m2 and SC-404 hybrid×8 plants/m2. Minimum of it was obtained in DC-370 hybrid×12 plants/m2.

Two field experiments were conducted at the Research Farm of Tabriz University in 2002 and 2003, to evaluate effects of shading on RATE and duration of GRAIN FILLING and yield of faba bean cultivars. Seeds of three faba bean cultivars including Barakat, Saraziri and HBP-B were sown by hand on 28 April 2002 and 7 May 2003. Both experiments were split- plot, based on randomizedcomplete block design with three replications. Shading levels and cultivars were allocated to the main and sub-plots, respectively. Shading treatments consisted of no shade (control), 18%, 48% and 70% shade. GRAIN FILLING duration was similar for faba bean cultivars. However GRAIN FILLING RATE and maximum GRAIN weight of Barakat and Saraziri were higher than HBP-B. Although, mean GRAIN weight of barakat and saraziri were significantly higher than HBP-B, but HBP-B was clearly superior in production of the number of GRAIN per plant and GRAIN yield per unit area. GRAIN FILLING duration under shade was 3-4 days longer than under control, which resulted in producing comparatively larger GRAINs under shade. Consequently, mean GRAIN yield of faba bean per unit area for shaded plants was higher than that for unshaded plants. Therefore, faba bean can be successfully used in intercropping and agro forestry, where shadind is a limiting factor.

Introduction: In semiarid regions with a Mediterranean climate, GRAIN-FILLING period of barley (Hordeum vulgare L. ) faces different kinds of biotic and abiotic stresses including water deficit, heat stress and foliar diseases. Current assimilation as a carbon source for GRAIN FILLING is dependent on light absorptive green surfaces after anthesis. This source decreases normally due to natural senescence and different stresses. Simultaneously, demand of growing GRAIN increases in addition to the demand of maintenance and respiration of live plant biomass. So stem reserves are one of the important carbon reserves for GRAIN FILLING. (Blum, 1998). Stem reserves are mainly in the form of WSC (Kuhbauch and Thome, 1989; Przulj and Momcivilic, 2001; Schnyder, 1993). The final GRAIN weight is one of the main determinant components of yield, which is determined by two factors: GRAIN FILLING RATE and GRAIN FILLING period (Blum, 1998, Yang and Zhang, 2005). These two components are influenced by environmental and genetic factors and are physiologically completely independent of each other. Ehdaie et al. (2008) studied GRAIN growth in 11 wheat genotypes. Under drought stress, 26% GRAIN weight reduction was due to 29 percent reduction in GRAIN FILLING RATE and 50 percent GRAIN FILLING period. The aim of this experiment was to investigate the changes in GRAIN weight and carbohydRATE concentration of four barley cultivars under end of season drought stress, and to investigate the role of stem reserves and current photosynthesis in GRAIN weight stability under drought stress. Materials and methods: A pot experiment was carried out in a factorial design with three replicates at the faculty of Agronomy, University of Shahid Chamran in the duration of 2010-2011 growing seasons. Four spring barley cultivars (Hordeum vulgare L. ) selected from preliminary experiment including Nimruz, Jonub, Nosrat and Torkaman were grown under two water treatments including water stress vs. fully irrigation. The chlorophyll Content of flag leaf was assessed from anthesis to maturity at 5-day intervals from the same-age plants. Sampling was done from anthesis to maturity at 5-day intervals from the same-age plants. The spikes were removed and the weight of nine middle GRAIN was measured. The linear RATE of GRAIN growth was estimated by The linear regression analysis for each cultivar in well-watered and droughted treatment. The penultimate internodes were sepaRATEd from stems and then frozen in liquid nitrogen after removing leaf sheet. Five main spikes at maturity were harvested for assessment of main spike GRAIN yield, the number of GRAINs and GRAIN weight. WSC were extracted based on Sonnewald et al. (1992) and measured according to Dubois et al. (1956). Results are expressed as milligrams of WSC per gram of fresh weight for WSC concentration. The mobilized WSC (MWSC) in penultimate internode was estimated as the difference between postanthesis maximum and minimum WSC concentration. Remobilization efficiency (Re) of WSC was estimated by the proportion (%) of postanthesis maximum WSC concentration of penultimate internode that mobilized. Result and discussion: Significant difference was observed among cultivars in WSCc at anthesis. Jonub showed the highest and Nosrat showed the lowest concentrations. Inspite of lower WSC concentration (WSCc) at anthesis, Torkaman and Nimruz could be set in the same group with Jonub, based on maximum WSCc (Fig. 1). The ratio of preanthesis WSC to total reserved WSC was different among cultivars. Jonub had the highest ratio, while Torkaman had the lowest ratio. Water withholding elevated remobilisation efficiency by 10%. Nosrat was affected the most by water-stressed conditions by increase of 47% in mobilised carbohydRATEs and increase of 44% in remobilisation efficiency. On the other hand, Nimruz and Jonub had high level of WSC remobilisation in both conditions and these cultivars weren’ t highly affected by drought. Water withholding increased the RATE of chlorophyll loss by 66%. Nosrat and Nimruz showed the highest and the lowest RATE of chlorophyll loss in both circumstances respectively. On the other hand, Jonub and Nosrat showed the highest and the lowest increase in this feature by entering drought. Drought decreased GRAIN FILLING RATE by 35 that resulted in decrease of 15% in GRAIN weight. Reduction by 17% was observed for yield of main spike by entering drought that was mainly due to the decrease of GRAIN weight, Because GRAINs per spike didn’ t change. Conclusion: Cultivars were different in WSC-related traits such as WSC concentration at anthesis, maximum WSC concentration and RATE of WSC accumulation in ten-day period after anthesis. Water withholding elevated WSC remobilisation efficiency. Water withholding increased the RATE of chlorophyll loss by 66%. Drought decrease the the RATE of GRAIN FILLING by 35%. The decrease of 15% in GRAIN weight led to decrease of 17% in GRAIN yield of main stem. Cultivars showed different manner about use of current photoassimilates and reserved WSC in the second phase of GRAIN FILLING that led to different changes in GRAIN weight by entering drought conditions.

In order to evaluation of the process of genetic improvement RATE and duration of GRAIN FILLING among wheat cultivars, the field experiments were conducted at the Agricultural and Natural Resource Research Center of Golestan province. in the growing seasons of 2007-2008 and 2008-2009. The 16 cultivars were sown in a randomized complete blocks design with three replications. The results showed that wheat cultivars had not changed during breeding activities in order to improve yield in GRAIN weight and duration of GRAIN FILLING while RATE of GRAIN FILLING was increased. Also RATE of GRAIN FILLING was improved %26.19, in 38 years of the release, was observed %0.7 and it improvement. This increase was due to increasing GRAIN number per unit area. In order to positive and significant correlation between GRAIN FILLING RATE and GRAIN yield it seems that selection for high yield and GRAIN FILLING RATE is possible without the need to increase of GRAIN FILLING duration.