Effect of some Natural Material Additives on Growth and Flowering of Tuberose (Polianthes tuberosa, L.) Bulbs

Abstract

Tuberose (Polianthes tuberosa, L.) has a good economic potential for cut flower trade and essential oil industry. A field experiment was conducted at Sakha Horticulture Research Station, Kafr El-Sheikh Governorate, Egypt, during the two successive seasons of 2013/2014 and 2014/2015 to study the effect of some natural materials, i.e. humic acid, yeast and garlic extracts, using two application methods, i.e. soil drench and foliar spray, on some vegetative growth traits, flowering, bulbs and bulblets productivity. The investigation aimed to improve plant quality and raise new formed bulbs and bulblets under local conditions. Results indicated that humic acid treatment followed by yeast then garlic extract significantly increased all traits under study. Soil drench method was superior for vegetative growth, flowering traits, bulbs productivity and chemical constituents compared to the foliar spray one. Application of humic acid as soil drench increased leaf length, number of leaves. Furthermore, it induced precocity in flowering, increased spike and rachis length, number of florets per spike, fresh weight of florets, fresh and dry weights of spike. Also, it significantly increased number of bulblets, fresh weight of clump, fresh weight of new formed bulb and its diameter. Besides, it increased chlorophyll (a) and (b), carbohydrates content, nitrogen, phosphorus and potassium percentage in the leaves compared to untreated plants in both seasons. Therefore, application of humic acid by soil drench method, at the rate of 9 ml/l after three weeks of planting tuberose bulbs, three times with three weeks' interval is important for improving plant quality and raising new formed bulbs and bulblets under local conditions.