Axillary shoot formation on Nicotiana tabacum L.

摘要

Axillary shoot (sucker) formation is an undesirable characteristic for commercial tobacco (Nicotiana tabacum L.) production. A comparison of axillary bud growth suggested that tested cultivars could be categorized based on their inherent capacity for potential sucker formation. Additionally, greater concentration of endogenous active gibberellins (GAs) was detected in axillary buds of a high sucker producing cultivar. Applications of retardant plant growth regulators (PGRs) reduced endogenous active GAs in the sub-apical region and consistently suppressed sucker growth. These results are consistent with the concept that rapid shoot growth, and therefore sucker formation on tobacco plants is associated with biosynthesis and accumulation of GAs. The inhibitory effects of selected PGRs, including flurprimidol (FLUR) on sucker growth during the vegetative phase of tobacco plant growth were further examined. FLUR eliminated the need for clipping in the float system, significantly retarding stem elongation, but increasing nutrient uptake and dry matter accumulation of seedlings. In the field, FLUR treated transplants exhibited normal and uniform growth, with reduced sucker growth, without compromising the whole plant architecture for leaf production. The expression of early sucker formation in tobacco most likely depends on environmental conditions during pre-transplanting seedling development. Low night temperature during seedling development induced axillary bud growth initiations (early sucker signs) on float seedlings. These signs were highly correlated with sucker formation on plants during post-transplant field growth. Increasing irrigation frequency in both ebb-flow (EF) and capillary mat (CM) sub-irrigation systems increased the number of field suckers, which was similar to float bed (FB) grown plants. In general, FB had the highest and CM the lowest tendency for sucker formation in the field.