For determination of optimum planting density and harvesting date for potato cultivars, a split split plot experiment in basis of RCBD design with four replications was conducted for two years (2001-03) at Behbahan Agricultural Research Station. Main plot consisted of three cultivars Arinda. Piccaso and Sante. Sub plot were three planting densities 5.3, 7.6 and 8.9 plants per square meter (15 75, 20 75 and 25 75 cm) and sub sub plot were three harvesting dates of 30 April, 15 May and 30 May. Combined analysis of variance showed significant effects of cultivar, planting density and harvesting date on total yield, marketable yield and yield components. Effects of cultivar and harvesting date on unmarketable yield and its components (small tubers, rotted tubers and secondary growth) were also significant. Effect of planting density on small and rotted tubers were not significant. Cultivar Sante produced the heighest total and marketable yield. Increase in planting density decreased mean of tuber weight and tuber number per plant. Planting density of 8.9 plants per square meter produced the highest total and marketable yield. The highest total yield was produced in the latest harvesting date, but unmarketable yield was high in this harvesting date. Based on the results, cultivar Sante, density of 8.9 palnts per square meter and harvesting date of 15 May can be recommend for Behbahan region.

In this study the effects of four quince harvesting times (at 10 - day intervals), in 2 years on fruit quality during cold storage for 5 months at 0˚C and 85% Relative Humidity were investigated. Fruits were picked from orchards in Flavargan region of Isfahan. Every month, pH, sugar content, acidity, TSS, tissue firmness of fruits were determined. Variance analysis shows that the effect of year on TSS, sugar content, and pectin was siginificant (α =1%) as well as on tissue firmness (α =5%). Harvesting time effect was only significanrt on sugar content while storage time showed a significant effect on TSS, Sugar content and acidity of fruits. Year and harvesting time interaction effect on sugar content and TSS was significant ( α=1%). Year and storage time interaction effect on pH, pectin and tissue firmness was significant while no significant effect on measured parameter was observed for harvesting time and storage time interaction. Simultaneous effect of year, Storage time and harvesting time on pH, pectin and tissue firmness was significant ( α=1%). Meanwhile average analysis by Duncan test showed that different harvesting times had no significant effect on measured parameters except on fruit sugar content. Acidty , pH., and TSS values were changing significantly durig storage. Sugar content of 4th and 5th months of storage was maximum. Pectin content, acidity and tissue firmness showed the maximum level at the first harvesting time while pH was maximum at the 2nd harvesting time. It was concluded that 4th harvesting time (181 days after flowering period) and 5 months of cold storage are the optimum conditions to keep the quality quince.

Planting date is one of the most influential factors in determining sugar beet yield and quality. Due to its effect on the length of plant growth period, i.e. the number of growth days received by the plant, planting date has a significant impact on crop yield and is one of the most influential and decisive factors in agricultural production. The selection of the harvest date is one of the pillars of vintage quality and sugar yield in sugar beets. However, it is difficult to define the harvest date and, more precisely, the maturity date of beet roots in a precise and absolute manner. Indeed, there are various stages and degrees of maturity based on environmental and climatic conditions such as temperature, precipitation, latitude, and others. Because sugar beet lacks a distinct physiological ripening stage, similar to cereals. Due to the effect of farm management, particularly the application of planting and harvesting dates, on the yield and quality of sugar beet, it is necessary to plan carefully in order to determine the optimal planting and harvesting dates for this crop in each region. Due to the risk of autumn frost and the necessity of transport planning to the sugar factory, farm management is crucial. On the basis of this information, the first harvest date should be determined, which has a suitable and acceptable yield of white sugar, and the product should be harvested and transported to the sugar factory as soon as possible.

To determine the effect of planting and harvesting dates on root yield and certain quality characteristics of sugar beet in the Bardsir region of Kerman province, a split -plot randomized complete block experiment with four replications was conducted. The main factor was the sowing date, which was applied at two levels: The first sowing date was April 21 and the second was June 5. The sub-factor was the harvesting date, which began on August 23 and occurred in nine stages with a 15-day interval in the relevant plots.

The results revealed that the sixth, seventh, eighth, and ninth harvesting dates in the first sowing date produced the highest root yield, and only in these four treatments the root yield reached more than 50 tons per hectare. The treatments of three first, second, and third harvest dates on the first sowing date and three fifth, sixth, and seventh harvest dates on the second sowing date produced the most nitrogen in the roots. The greatest amount of root molasses sugar was found in the first and second harvest dates on the second sowing date; in these treatments, the amount of root molasses sugar exceeded 5.8%. Also, the greatest amount of gross sugar was assigned to the fifth, sixth, seventh, eighth, and ninth harvests on the date of first sowing, and the amount of gross sugar in these five treatments exceeded 18%. In addition, the sixth, seventh, eighth, and ninth harvest dates had the highest white sugar yield on the first planting date. Due to the risk of autumn frosts and, on the other hand, transport planning to the sugar factory and farm management, it is necessary to harvest immediately if the desired white sugar yield is achieved.

According to the findings of this study, delay in planting sugar beet increased root impurities and decreased root sugar yield and percentage. Also, with the delay in harvesting for both planting dates, root impurities decreased and the proportion of crude sugar increased, resulting in a greater disparity between molasses and crude sugar and an increase in pure sugar. Due to the risk of autumn frosts and the need to transport the crop to the sugar factory, it is recommended that beet growers in this region plant on May 1 and harvest on November 15.

Currently deficiency of raw materials and initiative resources caused an increasing need of cellulose industries to new lingo cellulose products and resources. kenaf as a fibrous plant is considered along with the other plant sources that their bast has suitable fiber. This experiment was carried out in split–plot form with 4 replication in order to evaluation effect of harvest time and genotype on hemp production in Research Farm of Gorgan University of Agriculture Sciences and Natural Resources in 2007. Experiment factors were six genotypes consisting of cubana, Neiger, 9277, Cubana 2032 and 7551, and three harvest times consisting of 85, 105 and 135 days after swing. Result showed that yield, bast, pith, and stem yield were affected by harvest time. Bast to pith in second harvest time and leaf to stem in first harvest time was more than the other times. In addition, interaction between genotype and harvest time was not significant. Genotype Neiger was the best genotype for yield, bast, pith and leaf yield also Cubana 2032 and Cubana with 40.41 and 40.00 percent were the best genotypes for bast to pith ratio. Third harvest time was the best for most factors except leaf to stem ratio results of this study showed that increase in length of period of growing could be result in more production of fiber in kenaf.

In order to determine the optimum harvesting date in direction to improve the quality attributes, antioxidant and storage capacity in Hayward kiwifruit, this experiment were performed based on randomized complete block design with three replications during 2012-2013 cropping season in western north of Guilan province, Astara, Iran. The studied treatment were including of five harvest dates of kiwifruit such as 17, 23 and 30 Oct. and 7 and 14 Nov. 2013. Based on results of this experiment, the effect of harvesting date was significant on all measured traits in Hayward kiwifruit except for fruit density and vitamin C. The highest degree of kiwifruit firmness (9.35 kg. cm-2) and their soluble solids content (6.6 %) were observed at 23 Oct. and 14 Nov. 2013, respectively. Delayed harvesting of kiwifruit decreased total titratable acidity. But, antioxidant capacity of kiwifruit enhanced response to delayed harvesting date. Also, in this experiment there was negative and significant correlation between antioxidant capacity and total titratable acidity of kiwifruit (r= - 0.74**). But, the correlation coefficient between kiwifruit firmness and antioxidant capacity was positive and significant (r= 0.70**). In addition, the correlation coefficient between soluble solids and firmness was negative and significant (r= - 0.82**). Delayed harvesting up to 14 Nov. 2013 caused to increase the content of soluble solids and antioxidant capacity and enhancement of shelf life ability in Hayward kiwifruit. In general, the date of 14 Nov. 2013 can be recommendable to harvest Hayward kiwifruit and prolonging of its shelf life in region climatic condition.

Sugar is very important role in humanbeing feed. for sugar Beet production in tropical area detemine sowing and harvesting date is very important. For this reason three sowing date (1 sep, 20 sep and 10 oct) and three harvesting date (15 Apr, 15 may and 15 jun) in complete Blouck design as factorial with three replication in two year in Sarpol area condoucted. Results showed that the first sowing date has highest bolting and third sowing date has lowest bolting. Thirs harvest date has highest level of bolting. Root yield in the first sowing date more than the other. Interaction between two factors showed that 1 Sep sowing date * 15 May harvesting date for root yield was very better than the other interaction factors. The best date of sowing in this area was until 20 Sep and for date harvest was 15 May. For development of sugar beet caltivated in this area need to more investigation.

A factorial experiment based on a randomized complete block design with three replications was carried out in order to study the effects of tuber size، nitrogen fertilizer and harvest date on yield and yield components of potato. This experiment was conducted in a grower’s farm in Uraki village located in Chabahar city، in 2011. In this experiment، the treatments were two levels of tuber size (smaller and larger than 35 mm)، four levels of nitrogen fertilizer (0، 60، 120 and 180 kg ha-1) and two levels of harvest date (105 and 112 days after emergence). The results of analysis of variance indicated that effects of tuber size، nitrogen rate and tuber size × nitrogen rate interaction effect were significant for all of the studied traits at 0. 01 probability level. Effect of harvest date was significant on total tuber yield، number of large tubers، tuber yield and dry matter. The results of this experiment indicated increasing nitrogen up to 120 kg ha-1،increased total tuber number، number of large tubers، tuber yield and dry matter. But using up to 180 kg of nitrogen per hectare reduced these traits. According to the results of this research، it seems that under our experiments condition، tuber size larger than 35 mm، using 120 kg nitrogen per hectare which harvested 112 days after emergence date of tubers (1st of April) produced 41500 kg ha-1 tuber which is suitable to gain the highest yield of tubers for planting the ''Sante'' cultivar.

Short growing season in cold regions is an important factor in not achieving a maximum root yield in sugar beet crop. In an investigation on possible ways to limit the effect of short season culture on the crop, six harvest dates and three sugar beet varieties were considered. The experiment was conducted as a factorial with randomized complete block design in three replications, from 1996-1998 at Ekbatan Research station in Hamedan. Planting dates (The beginning of May) and all cultural practices were kept identical for all treatments. Sugar beet harvest was carried out at selected dates, and data were collected for statistical analysis. Results of ANOVA showed that there were significant differences among sugar beet lines, with BR1 showing the highest: root yield, sugar content and white sugar yield as companed to two other lines. Significant differences were observed for root yield, raw sugar yield, white sugar yield, sugar content, the coefficient of extraction and profit gained in different harvest dates. The two dates of Oct. 12 and Nov. 11, were superior to Sept. 23 and Oct. 2 in all parameters. The highest raw sugar and white sugar content were obtained in Nov. 11 harvest date as compared to others. The highest sugar yield and white sugar yield with 10.09 t/ha and 8.7 t/ha respectively belonged to the harvest of No. 11, which excepted for the No. 1, differed significantly with other harvest dates, coefficient of sugar extraction was increased for the late harvest and the three late harvests, were superior to the early ones regarding average profit obtained in three years and that of the year 2000. Harvest dates of Nov. 11, Nov 1, Nov. 21, Oct 12 and Oct. 2 were respectively 46, 39, 33, 26 and 17% higher as compared to profit of the Sept. 23 harvest date.

In order to determine the suitable fodder beet variety and the best planting and harvest dates in Jiroft region, an experiment was performed. Treatments consisted of two cultivars called 1025 and Lacinia, four planting dates (11 September, 02 October, 22 October, and 11 November) and two harvest dates (5 May and 5 June) evaluated in factorial split plot in 2021-2022 and 2022-23 in the research farm of the South Kerman Agricultural and Natural Resources Research and Education Center. Planting dates were assigned in main plots and harvest dates and genotype were randomly placed in sub-plots. Results of analysis of variance showed that the effect of planting and harvest dates on all studied traits including total yield, root and shoot yield, as well as root and shoot dry matter yield were significant (P ˂ 0.01). The effect of cultivar on root yield, root length, shoot dry matter (P ˂ 0.01) and root dry matter (P ˂ 0.05) was significant. The triple interaction effect was significant on all studied traits, except for shoot yield. Bolting was affected by planting date, variety and their interaction. Lacinia was resistant to bolting in all sowing dates. Comparison of the triple mean effect showed that the highest total yield (187.38 tha-1), root yield (136.77 t ha-1), total dry matter (27.69 tha-1), root dry matter (20.39 t ha-1) and shoot dry matter (7.30 tha-1) was related to the Lacinia on planting date of 10 October and harvesting date of 5 June.