This experiment was conducted to evaluate the effects of sowing date on yield and its components of 8 SWEET CORN hybrids in Jiroft area in 2007 at Agricultural Research Center of Jiroft and Kahnouj, Iran. The design was laid out as a split plot design based on RCBD with three Replications. The main factor had two levels of sowing date (August 22ed, September 6th) and subplots were 8 hybrids (EXO8716636, Obsession, Harvest Gold, Chase, Temptation, Challenger, Basin and Power House). The result showed that highest economical yield (ear fresh weight at economical harvest) were obtained in August 22ed with 27.54 ton/ha and ear fresh yield was 24.05 ton/ha in September 6. The highest and lowest ear fresh yield were obtained about from cultivar Basin 30.73 ton/ha hybrid temptation 20.42 ton/ha respectively. Maximum ear fresh yield with 32.42 ton/ha and 31.87 ton/ha were obtained from hybrid Basin and Power house in planting date August 22. Finally, SWEET CORN cultivars, Harvest Gold, Power House and Basin with August 22ed are recommended for the Jiroft region.

In order to determine of important agronomic characteristics of SWEET CORN hybrids and weed or without weed competition under different plant density at Iranian warm environment this experiment was conducted on 2006 at the HajiAbad plant research center, Hormozgan, Iran. The experiments were perform in a split split plot in contract to RCBD for 2 SWEET CORN (KSc.403 and Shimmer hybrids) as a main plots and weed control and non weed control on sub plots and three plant density 53, 67 and 89 thousand plant per hectare as a sub sub plots with 4 replications. The results showed that the difference of 2 hybrids about seed yields, number of seed per row and number of row per ear were significant. Then, weed control could increase the seed yield near 7.8%. Maximum yield of seed CORN was about 9700 kg/ha for Shimmer hybrid at 89000 plant density per hectare under full weeds control condition. Finally the Shimmer hybrid of SWEET CORN showed better studied characteristics in compare to KSc.403, and Shimmer could produce the highest seed yield by increase the plant density from 53000 to 89000 too, but under weed control.

In order to comparison and determination of the best drought tolerance indices in SWEET CORN hybrids, an experiment was conducted using a randomized complete block design in split plot lay out with three replications at Seed and Plant Improvement Institute in Karaj in 2006. Three irrigation levels (irrigation after 75 as control, 100 and 125 millimeters cumulative evaporation from class A evaporation pan) were assigned as main plots and 12 SWEET CORN hybrids include KSC403su, Chase, Esquire, Rival, Reveille, Diva, Shimmer, Shaker, PS107, Golda, Royalty and Rana were considered as sub plots. Mean Productivity (MP), Tolerance Index (TOL), Geometric Mean Productivity (GMP), Stress Susceptibility Index (SSI), Stress Tolerance Index (STI) were used to evaluate tolerance or sensitivity to drought stress of the hybrids. STI and GMP indices had a positive and significant correlation with grain yield in non-stress and stress conditions (mild and severe stress treatments). STI and GMP indices showed that Hybrids Diva and Golda had optimum yield in non-stress condition but their yield decreased in severe stress condition. Hybrids KSC403su, Esquire, Shimmer and Shaker had low yield in non-stress but they had suitable yield in severe stress condition. Hybrids Chase, Rival and Reveille had low yield in non-stress and severe stress conditions. Hybrids PS107, Royalty and Rana had optimum yield in both non-stress and stress condition. Therefore, they can be recommended to use in stress and optimum conditions.

In order to study effect of there plant densities on phonological traits of 5 exotic SWEET and super SWEET CORN varieties, this experiment was carried out in a factorial design based on RCBD with 3 replications. Experiment was done at research field of Seed and Plant Improvement Institute at Karaj during 2008. Results showed that, effect of various plant densities have non-significant on days to tassel formation, pollination and ASI, but the studied densities showed some effect on days to silk development, with respect to the experiment results, the increase of plant density from 75000 to 95000 plant/ha, caused the days to silk development to increase too, and varieties which needed more days to silk development, were also late maturing varieties. There was significant difference between the studied values regarding the days to tassel formation, the days to pollination, and the days to silk development which was absent with respect to ASI. The Obsession variety showed the highest number of days to tassel formation, pollention and silk which indicates its late maturing in comparison to other studied varieties.

To evaluate the reaction of some SWEET CORN varieties to new urea sulfonyl and mixture herbicides, an experimental research based on a randomized complete block factorial design with three replications was conducted. The first and second factor were SWEET CORN variety and chemical control included nicosulfuron (Cruz), nicosulfuron (Cruz) +bromoxinyl+MCPA (brimicide MA), foramsulfuron (equip), Rimsulfuron+Nicosulfuron (Ultima), Mesotrion+S-Metolacholor+Terbuthlazine (Lumax 537.5 SE), with three cultivars of SWEET CORN including golden (KSC403su), Merit and Chase, weed free, weed infested with three replication in each block. Assessment rate included injury SWEET CORN on EWRC, SWEET CORN varieties and weeds biomass at 4 weeks after spraying. Merit variety was ruined by nicosulfuron, nicosulfuron+bromoxinyl+MCPA, rimsulfuron and foramsulfuron+nicosulfuron application as susceptible cultivar, and Golden and Chase with minimum injury by these herbicides usage known as tolerance varieties. Mesotrion+S-Metolacholor+ Terbuthlazine was only herbicide which applicable on Merit variety. The herbicides effect was significant on stem diameter, leaf number, plant dry weight, plant height, ear length, ear diameter, cob weight and grain weight per ear. The highest and lowest grain yield related to Chase and Merit varieties, respectively. Golden variety had medium grain yield between two varieties. Also, the result showed that red root pigweed, common purslane, binweed, common lambsquarter, purple nutsedge, black nightshad density and dry weight reduced by all of the herbicides compared control treatment, significantly. Totally, Mesotrion+S-Metolacholor+Terbuthlazine were only herbicide that applicable in all of SWEET CORN varieties without any injury to crop and high effect to all weeds control.

SWEET CORN, Zea mays Var. Saccharata is the youngest form of CORN that arose after an accidental mutation in the common CORN, and the Native Americans and Indian tribes began to cultivate it after becoming aware of the differences. The first registered variety of SWEET CORN was named Black Iroquois by European settlers in 1779. In the 19th century, white OP (open pollination) cultivars became popular in the United States. Two varieties of this type that are still cultivated and consumed are the Country Gentleman variety (with elongated and small seeds and irregular rows, also called Shoepeg CORN) and the 'Stowell's Evergreen' variety. Scientific developments in the field of plant breeding, including the hybridization technology by inducing traits such as ripening at the same time and improving the quality of cobs and resistance to diseases, created tremendous changes in the production of SWEET CORN in the 20th century. This article with an overview of the successes achieved in creating new cultivars and improving the quality and marketability traits of SWEET CORN, its genetic differences from common CORN, and the role of hybridization as one of the common tools of classical breeding to achieve superior genotype qualities are emphasized in SWEET CORN. Classification of SWEET CORN hybrid cultivars based on factors such as genes affecting carbohydrate metabolism and endosperm sugar percentage, planting time until harvest, seed color (yellow, white, pink, purple, and black), cob shape, and type of consumption (freshly eaten, Freezing, canning and exporting) forms another part of this article. Examining SWEET CORN breeding methods shows that despite the use of a number of specific techniques and theories, due to the different results of each method, the effect of external pollination, and the high perishability of the final product, SWEET CORN breeding is very different in practice. The most important methods in SWEET CORN breeding have been reviewed in another part of this article. These methods include pedigree breeding, production of synthetic and composite masses, backcrossing and breeding with the help of molecular markers, as well as selection for some special traits such as edible quality, seed production, improved germination in Sh2 seeds, and resistance to pests and pathogens. In the final part, all kinds of SWEET CORN varieties, including commercial hybrids for fresh consumption and hybrids suitable for processing, have been introduced according to the genetic changes that have taken place in SWEET CORN cultivars since long ago.

This study was carried out to evaluate drought tolerance of 12 SWEET CORN hybrids in 2006 at Seed and Plant Improvement Institute in Karaj. Treatments were arranged as a split-plot experiment in randomized complete blocks design with three replications. Main plots included three irrigation levels (Irrigation after 75, 100 and 125 mm evaporation from class A evaporation pan as normal, mild and high stress conditions respectively) and 12 hybrids (KSC403su, Chase, Esquire, Rival, Reveille, Diva, Shimmer, Shaker, PS107, Golda, Royalty and Rana) were assign as subplots. Irrigation regimes and hybrid effects for all of the traits and their interaction effect for 1000 kernels weight and grain yield were significant (p£0.01). Increasing drought stress from normal irrigation to mild stress and high stress conditions were resulted in decreasing all the traits significantly. The maximum and minimum grain yields were obtained from PS107 and Rival hybrids (8.35 and 4.86 t/ha respectively). This experiment revealed that delay in irrigation more than 75 mm evaporation decreases the yield. It recommended that hybrid PS107 is cultivated where there is enough water for irrigation. In low available irrigation water using of hybrids Rival, Diva and Golda is not recommended.

In spite of optimal qualitative traits of SWEET CORN plant, its cultivation is limited due to some problems in germination, poor vigor, seed wrinkling and seedling weak establishment in the soil, using mineral compounds in seed coating could improve germination and seedling growth indices, and physical characteristics of SWEET CORN seeds. In order to improve efficacy of SWEET CORN seed using seed coating, this experiment was conducted based on three-factor factorial in a completely randomized design with four replications of 25 seeds at the laboratory at the Department of Agronomy and Plant Breeding, Yasouj University, Iran, in 2018. The first factor included the concentrations of chitosan solutions (zero- 0.3% acetic acid, 0.5 and 0.75%), the second factor was gum arabic (zero- distilled water and 0.4%) and the third factor was V10K2.5P5 coating composition (10, 2.5 and 5 fold to seed weight respectively in Vermiculite (V), kaolin (K) and perlite (P)) and no coating treatment. The interaction effect showed that that the highest seedling length vigor index (183.24) was related to the coating treatment of gum arabic 0.4% and coating composition of V10K2.5P5 that had a significant difference with a treatment that had the lowest seedling length vigor index (85.70) from the coating treatment gum arabic 0.4% and no coating composition. The overall results showed that the coating treatment of chitosan 0.5% + coating composition of V10K2.5P5 + gum arabic 0.4% was more effective treatment on germination indices and seedling and physical characteristics of SWEET CORN seeds compared to other treatments.