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.

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 %**).

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.

Dry matter remobilization, GRAIN FILLING rate and duration has principle role on rice GRAIN yield, and environment condition directly affect on them. For study the influence of climate factors a factorial field experiment in randomized complete blocks design with three replications conducted at Haraz Extention and Technology Development Centre in Spring 2013. Treatments included rice cultivars namely; Samadi, Tarom Hashemi, Local Tarom, Shiroudi, Keshvari, Gohar and transplanting times (5th may, 20th may and 10th June). Results showed that dry matter remobilization rate, stem dry matter remobilization efficiency, GRAIN FILLING rate and duration, and GRAIN yield varied significantly among different transplanting times. Transplanting time on 5th may was higher than other two transplanting dates in all traits except for GRAIN FILLING rate. Tarom Hashemi had highest and improved variety, Shiroodi had lowest GRAIN FILLING rate. Dry matter remobilization rate, Stem dry matter remobilization efficiency, EFFECTIVE GRAIN FILLING duration, and GRAIN yield was higher in Shiroudi among rice cultivars. GRAIN yield negatively correlated with GRAIN FILLING rate. Increasing in GRAIN FILLING duration with increased dry matter remobilization had more EFFECTIVE role in rice cultivars GRAIN yield. Increasing temperature in vegetative growth phase with increasing in accumulated growing degree day accompanied with decreasing in tiller number, less tiller number caused higher GRAIN FILLING rate and lower GRAIN FILLING duration and dry matter remobilization restriction that decreased GRAIN yield.

In order to study the effect of heat stress during GRAIN FILLING PERIOD on yield, yield components, GRAIN FILLING rate and duration, a field experiment was carried out during 2010-2011 growing season in Ahvaz conditions, as factorial based on randomized block with three replicates. The experimental factors consisted of 10 mid maturity bread wheat genotypes (Charnran, Atrak, Aflak, Dez, Falat, Darab2, Kavir, Pishtaz, S-78-11, S-83-3) and two sowing dates, including the optimum (12 Nov.) and late sowing date (21 Dec.). The results showed that in late sowing date, yield and yield components were reduced significantly in all genotypes. Atrak and Pishtaz had the minimum (8.2 %) and maximum (26.3%) reduction of GRAIN yield, respectively. In late sowing date, Kavir and Charnran had the highest (584.3 and 579.8 g.m-2, respectively) and Pishtaz had the lowest (446.3 g.m-2) GRAIN yield. Based on the heat susceptibility index among all genotypes, Atrak was heat- tolerant, Charnran, Kavir, Dez, Falat and Aflak were moderately tolerant and S-78- 11, S-83-3, Darab2 and Pishtaz were heat- susceptible. The shortening of EFFECTIVE GRAIN FILLING PERIOD in late sowing date resulted in reduction of thousand-GRAIN weight and increase in GRAIN FILLING rate could not compensate for .GRAIN FILLING PERIOD reduction. Overall, it seems that only the higher GRAIN growth rate under heat stress during GRAIN FILLING PERIOD cannot contribute to the higher GRAIN yield and other factors such as GRAIN FILLING PERIOD and number of GRAINs per spike seem to be more important.

An experiment was conducted at Rasht Rice Research Institute, in 2001 to study trait relationships and to determine the direct and indirect effects of different characteristics on GRAIN yield of rice (Orgza saliva L.). A 9x2 factorial experiment in complete randomized block design with 3 replications was used. The two factors were 9 cultivars, namely: Hashemi, AliKazemi, Binam, Sepeedroud, Nemat, Khazar, Taichung, Chanto, and Usen, and 2 planting patterns (15x15 cm and 30x30 cm). Significant differences were detected among cultivars, between planting patterns, and their interaction effects. The direct effect of the number of panicles/m2 on GRAIN yield was positive and significant in both planting patterns and their combined analysis. Heading date had a positive and significant direct effect on the number of panicles/m2 in both planting patterns and their combined analysis. Only in 30x30 cm planting pattern, a positive correlation was found between biomass at heading date and the number of panicles/m2. GRAIN weight per plant had a direct and positive effect on panicle weight in the 3 cases studied. Also, in all the cases studied, flag leaf area had positive direct effects on GRAIN-weight per plant. GRAIN FILLING i"ate and EFFECTIVE GRAIN FILLING PERIOD increased in 30x30 cm planting pattern. Native cultivars demonstrated longer latent PERIOD. GRAIN FILLING rate and EFFECTIVE GRAIN FILLING PERIOD showed positive direct effects on GRAIN yield in both plantings. According to the results obtained, an increase in the number of panicles/m2,rate of GRAIN FILLING, and EFFECTIVE GRAIN FILLING PERIOD would enhance GRAIN yield. Selection for heading date, GRAIN yield per plant, and flag leaf area would also indirectly increase GRAIN yield.

The linearity of harvest index (HI) increase has provided a simple means to analyse and predict seed growth and yield in experimental and simulation studies. The objective of this study was to Investigate harvest index linear increase and related parameters in FILLING GRAIN PERIOD of chickpea (Cicer arietinum) crops grown under well-watered conditions. A field experiment, with 3 sowing dates and 4 plant densities, was conducted in Gorgan during 2004-2005. Crop biomass and phenological stages were measured between emergence and maturity. Harvest index increased in seed FILLING PERIOD linearly. The effect of density on harvest index linear increase was not significant but there was different between sowing date. The time of beginning harvest index linear increase, decreased from 26 to 8 days from first sowing date to third one, but there was any difference in plant density. From obtained parameters in this research can use in chickpea growth simulation models.

In order to investigate the effects of free living nitrogen fixing bacteria application and time of nitrogen spraying on contribution of stem reserves in GRAIN yield, rate and EFFECTIVE GRAIN FILLING PERIOD of Triticale, a factorial experiment was conducted based on a randomized complete block design with three replications in Research farm of the Faculty of Agriculture, University of Mohaghegh Ardabili in 2012. Treatments consisted of different nitrogen spraying times in four levels (no spraying as control, spraying in boot stage, ear emergence, GRAIN FILLING PERIOD) and seed inoculation with plant growth promoting rhizobacteria in four levels containing (without inoculation as control, seed inoculation with Azotobacter chroococcum strain 5, Azospirillum lipoferum strain OF, Psedomunas putida strain 9). Results indicated that spraying time of nitrogen fertilizer and seed inoculation with free living nitrogen fixing bacteria had significant effects on yield, yield components, rate and EFFECTIVE GRAIN FILLING PERIOD of Triticale. Maximum of GRAIN weight (0/054 gr) and EFFECTIVE GRAIN FILLING PERIOD (34. 17 days) were obtained in seed inoculation with Azotobacter× nitrogen spraying in boot stage. Maximum of contribution of stem reserves in GRAIN yield (30. 63 %) was obtained in no nitrogen spraying × no seed inoculation with PGPR and minimum of it (8. 12 and 8. 13 %) were obtained in nitrogen spraying in boot stage × seed inoculation with Azotobacter and spraying in ear emergence × seed inoculation with Azotobacter. It seems that in order to increase the GRAIN yield, rate and EFFECTIVE GRAIN FILLING PERIOD of Triticale, it can be suggested that nitrogen spraying is applied in boot stage and seed inoculation with Azotobacter

For studying genetic variation for GRAIN FILLING rate and GRAIN FILLING PERIOD  and relationship with GRAIN yield, 10 barley genotype: Bomi, Torkaman, Eize, Siah, Sahra,1-yeknavakht, 14G, 11G, 5G and 15G, cultivars ,introduced by Golestsn agriculture research centre, Were studied in randomized complete block design at 4 replication at 84-85.were studied. This genotype varied for both rate and duration GRAIN FILLING parameter and had significant difference. Torkaman had maximum GRAIN FILLING rate and minimum was for 1-yeknavakht.the average of GRAIN FILLING rate was 1.59 mg/day and average of GRAIN FILLING duration was 29.8 days. Positive correlation between GRAIN FILLING rate and duration with GRAIN yield showed that, they increased from low yield genotype to high yield.14G had maximum and Torkaman had minimum GRAIN FILLING duration. Negative no significant correlation between GRAIN FILLING rate and GRAIN FILLING duration.14G showed that have higher GRAIN yield than other genotype and with receive lower GDD, achieved to the physiological maturity