EFFECT OF PLANTING CONDITIONS AND PLANTING DATES ON VEGETATIVE GROWTH, FLOWERING, BULBS PRODUCTION AND CHEMICAL CONSTITUENTS OF IRIS TINGITANA CV. WEDGEWOOD PLANTS

The present experiment was consummated throughout two successive seasons (2016/2017 and 2017/2018) at the nursery of Horticulture Research Institute, Agricultural Research Center, Giza, Egypt with the aim to solve one of the most important problem facing most of winter cultivated crops under local condition in Egypt. It was intended to overcome the problem of high atmospheric temperature which prevailed during the early months of autumn and consequently led to deteriorate plant quality of many crops. Thus, the effects of shading and open field conditions (saran house of 65% shading and full sun light of open field conditions), besides the effects of planting dates and their interaction were investigated on growth, flowering, bulbs, bulblets yield and quality and chemical constituents of Iris tingitana cv. Wedgewood plants. Main results of the study could be summarized in the following: Growing the bulbs preliminary under shading followed by open field conditions was the best for improving most of plant traits studied in the two seasons as produced the highest values of number of leaves/plant, induced early flowering, gave the highest values of spike stem length, increased fresh weight of cut spike and the newly formed bulbs. Moreover, raised fresh weight of bulblets and bulblets yield. With respect to the effect of planting dates, planting the bulbs on October 15th, gave beneficial effects in most cases as it was the best planting date in raising vegetative growth height. Moreover, it gave the utmost high values with significant effect on number of leaves/plant. Also, planting the bulbs on October 15th caused a clear decrement in the time required for flowering, succeeded to raise spike stem length, produced the highest bulblets yield and the highest bulb circumference. Meantime, planting the bulbs at the earliest date of September 15th was the best for elevating fresh weight of cut spike and produced the heaviest fresh weight of bulbs, and recorded the utmost high values of bulblets yield. Referring the effect on chemical constituents the result showed that bulbs planted under open field condition followed by shading was the best in raising pigments content in leaves (chlorophyll a, b and carotenoids) in the two seasons. Meanwhile, the different planting conditions gave means closely near together for the effect of the different planting conditions on total carbohydrates content in the newly formed bulbs, Moreover, clear increment on nitrogen % in the new bulbs was observed due to growing bulbs grown under open field condition throughout the growing season. Whereas, bulbs grown under open field, followed by shading condition, as well as those which grown under shading condition throughout the growing season gave the highest records of phosphorus % in the new bulbs in both seasons. Results revealed also the prevalence of growing bulbs under either open field condition throughout the growing season in both seasons or those grown under shading followed by open field condition in the first season in raising potassium % accumulation in new bulbs. Also, clear influences on chemical constituents of the plants were observed due to using the different planting dates. The utmost high values of pigments content in leaves was noticed as a result of planting the bulbs on September 15th. Moreover, the highest records of total carbohydrates in new bulbs were gained as a result of planting the bulbs in the same date (September 15th) in both seasons. Negligible differences on nitrogen % in bulbs were observed due to the effect of the different planting dates used in both seasons. Whereas, planting the bulbs on October 1st was the best in elevating phosphorus % in bulbs in the two seasons. Meantime, planting the bulbs in the earliest date of September 15th was the best for producing the highest potassium % in bulbs in the two seasons. From the aforementioned results and interaction it could be recommended to plant the bulbs under shading condition, followed by open field condition with planting the bulbs on October 15th for improving plant quality of Iris tingitana cv. Wedgewood.