لخّصلي

Two field experiments were conducted on a sugarbeet field at Banger El-Sokar area, Borg El Arab area, Alexandria Governorate, naturally infected with the root-knot nematode, Meloidogyne javanica, during the 2021/2022 and 2022/2023 seasons to study the effect of four planting dates and four sugarbeet cultivars on root-knot nematode reproduction, and crop productivity and quality.Hence, delaying the planting date can be considered as an agricultural method for nematode control.Delaying the planting date of sugarbeet from 10th August to 10th November significantly reduced the numbers of the second stage juveniles larvae of nematodes in the soil from 31436 to 6145, the different stages in the root system from 3615 to 1296, and the final nematode population from 35051 to 7441, this decrease is 71.69, 48.79 and 69.30%, compared to the first planting date, respectively, while the value of the reproduction factor decreased significantly from 19.47 to 4.13-folds, compared to the initial population (Pi).Sugarbeet cultivar, Oscar Poly recorded the highest significant reduction in the values of the studied nematode reproductive traits, and it also achieved the highest increase in top, roots, raw sugar and recoverable sugar yields (tons/fed) at all tested planting dates, compared to the other sugarbeet cultivars.Therefore, Oscar poly cultivar is suitable for cultivation at all tested planting dates, while cultivars, Francescan, Mirador and Sandorare suitable for cultivation during the 4th planting date only in soil contaminated with root-knot nematode, M. javanica at semi-arid lands.

Two field experiments were conducted on a sugarbeet field at Banger El-Sokar area, Borg El Arab area, Alexandria Governorate, naturally infected with the root-knot nematode, Meloidogyne javanica, during the 2021/2022 and 2022/2023 seasons to study the effect of four planting dates and four sugarbeet cultivars on root-knot nematode reproduction, and crop productivity and quality. The planting dates were 10th August, 10th September, 10th October, and 10th November. The tested sugarbeet cultivars were Francescan, Mirador, Oscarpoly and Sandor. The results showed that planting date had a significant effect on the traits of nematode reproduction, productivity and quality of sugarbeet traits. Delaying the planting date of sugarbeet from 10th August to 10th November significantly reduced the numbers of the second stage juveniles larvae of nematodes in the soil from 31436 to 6145, the different stages in the root system from 3615 to 1296, and the final nematode population from 35051 to 7441, this decrease is 71.69, 48.79 and 69.30%, compared to the first planting date, respectively, while the value of the reproduction factor decreased significantly from 19.47 to 4.13-folds, compared to the initial population (Pi). On the other hand, all crop components and most quality traits increased significantly with delaying the planting date. When the planting date was delayed from 10th August to 10th November, the top yield increased significantly from 12.24 to 14.76 tons/fed, the roots yield from 19.81 to 25.48 tons/fed, the raw sugar yield from 2.97 to 4.17 tons/fed and the recoverable sugar yield from 2.35 to 3.44 tons/fed. These increases were 20.59, 17.91, 24.85 and 28.84%, respectively, compared to the first planting date. Also, the latest planting date for sugarbeet significantly increased the sugar content %, recoverable sugar %, sugar loss in molasses yield (tons/fed.), and quality index % by 5.05, 8.08, 18.33 and 3.39%, respectively. Sugarbeet cultivar, Oscar Poly recorded the highest significant reduction in the values of the studied nematode reproductive traits, and it also achieved the highest increase in top, roots, raw sugar and recoverable sugar yields (tons/fed) at all tested planting dates, compared to the other sugarbeet cultivars. While, Francescan, Mirador and Sandor cultivars recorded the highest values for the same yields during the last planting date (10th November), compared to the other tested planting dates, where the level of nematode infection is lower. Therefore, Oscar poly cultivar is suitable for cultivation at all tested planting dates, while cultivars, Francescan, Mirador and Sandorare suitable for cultivation during the 4th planting date only in soil contaminated with root-knot nematode, M. javanica at semi-arid lands. The latest planting date for sugar beet, compared to other planting dates, achieved the highest significant reduction in nematode reproduction rate, and the highest significant increase in sugar beet productivity. Hence, delaying the planting date can be considered as an agricultural method for nematode control.