Determination of the most suitable planting and harvesting dates for five new varieties

This research was performed for detennination of the most suitable planting and harvesting dates for five common varities in morth-khus~stan on the basis of a split split plot design with four replications in safiabad agricultural research conter for 2 years ( 1991-1993).The .treatments included: five conunerical varities (karadj BRt , Ardabil BRI , mst II 19669- ps , polybeta and H5505) in the main plots, three planting dates ( september 16th , october 7th and Nevember 31 th) in the split"plots and four harvesting dates (April 9th , May lOth and June 10th) and july 11 tit) ih the split split plots . The results of variance analysis indicated that the ,ander- comparison varities resulted in different root yields by the method of LSD - the planting dates also resulted in different root yield , so that the date of 'october 7th with a root yield of 62.81 tlha has been the best treatment among all the planting dutes. The harvest dates had great effects on root yields and in LSD method placed in four distinct groups. In this experiment ,the harvest date of Jully 11 th, with 67.81 tlha root yield , was the best treatment and in comparison with the harvest date of April 9 th had an yield increase of 46% . two - way effects of varities and harvest dates ,planting and haITest dates were significant, and the highest most yield (76.34 tlha) was produced by polybeta variety . 2) sugar content: acording to the table of variance analysis (table3-9) the percentage of sugar has significantly affected by planting and harvesting dates. Sooner planting (september) and harvesting after June have resulted in roots with higher sugar content. The highest (IS .14%) and the lowest (12.86%) percentages of sugar have been obtained by planting on september 16th and November 31 th respectively. However harvesting on July 11th (with 14.9% sugar) and . April 9th (with 13.29% sugar) were the best and least harvesting dates, r~spectively. Two- way effects of varieties and planting, varities and harvesting, and planting and harvesting dates were significant for sugar content (%) . that indicate agrotechnical factors are very important in quantity and quality of sugar beet. 3) white sugar yield: , table of variance analysis (table 3-9) showed that the mentioned treatmeats were different trom one another. In the respect of their effect on white sugar yield. Therfore the varieties ranked in two distinct groups.Karadj BRI , mst II 19669 p-5 and polybeta ranked in the first groups and the other varieties ranked in second groups. Sugar yields of first, second and third planting dates were 7.83, 7.73 and 4.84 tlha respectively therefore the sooner planting is better than other treatments. The effects of harvest treatments on white sugar yiel~ were like to root yield and the highest sugar yield (8.5 tIha) was related to the harvest date of july 11 th ,that had an increase of 66% in comparison to the harvest dates of Aprill 9 tho 4) Bolting : According to the table of variance analysis, planting date, varities, harvest date ,___year "and "their reciprocal effects have had significant statisticalIy effects on increasing the number of bolted roots. The percentage of bolting was 25.2 in the year of 1991- 92 the bolting percenFages of the varieties kardj BRr , mst -19669 p-5 ,polybeta and H5S0S\\ were 12.8 ,23.4. I I.1 ,9.4 and 17.93 respectively. the planting _ dates had great effects on bolting. the bolting percentages of the flTst. second and third planting were in this manner: 28.03 , 15.4 and 1.4. there-fore , sooner plantings have resulted in higher jercentgs of bolting. the bolting for harvest dates of Aprill 9 th , may 10 june 10th and yully 11 th were 1.04 , 14.58,20.8 and 33.21 percentively and any delay in harvest increased it.