[Effects of Some Agricultural Requirements on the Growth and Productivity of Some Ecological Genotypes of Anise and Determination of Critical Period for Weed Control in its Fields]

This investigation was carried out at the farm of the Faculty of Agriculture- Damascus University during the growing season 2010-2011 in two separated trails. The First one aimed to determine the effect of seedling rate on yield component of four ecogenotypes of Anise plant, (Pimpinella anisum L.) which were collected from different places of Syria: Damascus (Hena, Saasaa), Homs and Edlib. Sowing rates were (10, 15 and 20 Kg/ha.). Trial was laid out using completely randomized block design with three replications for each treatment. The second one was conducted to determine the critical period of weed competition to anise plants. An ecotype of anise collected from Saasaa from Damascus countryside was grown in Damascus under rainfed conditions with supplementary irrigation. Two types of trails were conducted, the first one was with no weeding for certain periods (2, 4, 6, 8 and 10 weeks) and the second treatment with weeding for certain periods (2, 4, 6, 8 and 10 weeks). Trail was designed as completely randomized block with three replications. Studied traits were: plant no. at harvest, no. of umbels/plant, no. and weight of seeds/umbel, yield of plant dry weight and seed yield and finally critical weed competition. Results of first experiment showed that studied traits differed according to seeding rate and the ecotype. There was a significant differences for the treatment of seeding rate of 15 kg/ha., on seed yield. Regardless the ecotype, increasing the seeding rate up to (20 kg/ha.) resulted in maintenance of highest number of plants/unit area, but that was accompany with reduction in fertile umbels and seed weight. Statistical analysis showed that the ecotype of Edlib recorded the highest seed weight/ plant and highest seed yield/ planted area, especially with the seeding rate of 15 kg/ha. However, the results showed the seed components of Anise (plant number at harvesting, weight of seeds/plant) and seed yield were affected by the ecotype and seeding rate. However some characters did not affected by the trail, like, plant height, no. of branches and umbels, no. of fruits in an umbel, weight of thousand fruits, dry weight. Increasing the seeding rate (20 kg/ ha.) gain the highest no. of plants/ area at harvesting stage as compared to other seeding rates, and that accompanied with lowest no. of empty umbels and fruit weight, the lowest seeding rate 910 kg/ ha.) showed highest fruit weight, highest dry weight, highest oil percentage in fruits, while the medium seeding rate (15 kg/ha.) showed only highest fruit yield/area. Statistical analysis revealed that the Edlib type has the weight of fruits, dry weight and yield but without significant difference with Homs type especially at the rate of 15 kg/ha. Results showed the yield components (plant no. at harvest, fruit weight) were affected by the plant 83 ecotype and seeding rate. Correlation studies revealed a negative significant relation between no. of plant at harvest and fruit weight and positive significant relation between fruit yield and no. of branches and umbels, also with filled umbels, no. of fruit/ plant and dry yield. Results of critical weed competition period showed positive significant value for all traits in weeded plots except for the plant height and weight of thousand fruits (2.24 and 0.9 m. plants/ ha.). in weeded control and unweeded control for ten weeks. Weeded trials, showed highest no. of branches, umbels compared to un weeded plots. the highest no. of empty umbel was in weeded plot for 6 weeks and highest no. of filled umbels was with 4 weeks weeding. Weeded control plot gave highest weight of fruits (240.3 fruits/plant and 0.51 g/ plants resp.) as compared to two week trails, and that reflect positively on the yield of anise, as the control gave the highest yield, 1.13 tons / ha. and lowest value in the unweeded control (0.261 kg/ha.)and that show the importance of removing weeds and prevent their competition to anise crop. we noticed that the plant height, weight of 1000 seeds, did not affect by weeding or non weeding and it time. correlation study between studied characters in critical weed period showed a positive significant relation between plant no. at harvest and almost all other characters, except the plant height which correlated positively with no. of branches and umbels. Also their was a positive significant relation between fruit yield and dry weight (r=0.83**) and between them and other characters except plant height ( r=0.07 and r= 0.13). The critical weed competition result diagram cleared that the period from the second week after germination till the end of forth week is the crucial period for weed competition, and has the great influence in anise crop development, and out of this period, weeds have less effect.