Asad A, Blamey F P C, Edwards D G
School of Land and Food Sciences, University of Queensland, Brisbane, Queensland 4072, Australia.
Ann Bot. 2003 Oct;92(4):565-70. doi: 10.1093/aob/mcg179. Epub 2003 Aug 21.
Foliar application may be used to supply boron (B) to a crop when B demands are higher than can be supplied via the soil. While B foliar sprays have been used to correct B deficiency in sunflower (Helianthus annuus L.) in the field, no studies have determined the amount of B taken up by sunflower plant parts via foliar application. A study was conducted in which sunflower plants were grown at constant B concentration in nutrient solution with adequate B (46 micro m) or with limited B supply (0.24, 0.40 and 1.72 micro m) using Amberlite IRA-743 resin to control B supply. At the late vegetative stage of growth (25 and 35 d after transplanting), two foliar sprays were applied of soluble sodium tetraborate (20.8 % B) each at 0, 28, 65, 120 and 1200 mm (each spray equivalent to 0, 0.03, 0.07, 0.13 and 1.3 kg B ha-1 in 100 L water ha-1). The highest rate of B foliar fertilization resulted in leaf burn but had no other evident detrimental effect on plant growth. Under B-deficient conditions, B foliar application increased the vegetative and reproductive dry mass of plants. Foliar application of 28-1200 mm B increased the total dry mass of the most B-deficient plants by more than three-fold and that of plants grown initially with 1.72 micro m B in solution by 37-49 %. In this latter treatment, the dry mass of the capitulum was similar to that achieved under control conditions, but in no instance was total plant dry mass similar to that of the control. All B foliar spray rates increased the B concentration in various parts of the plant tops, including those that developed after the sprays were applied, but the B concentration in the roots was not increased by B foliar application. The B concentration in the capitulum of the plants sprayed at the highest rate was between 37 and 93 % of that in the control plants. This study showed that B foliar application was of benefit to B-deficient sunflower plants, increasing the B status of plant tops, including that of the capitulum which developed after the B sprays were applied.
当作物对硼（B）的需求高于土壤所能供应的量时，可采用叶面喷施的方式为作物补充硼。虽然在田间已使用硼叶面喷施来纠正向日葵（Helianthus annuus L.）的硼缺乏问题，但尚无研究确定通过叶面喷施向日葵植株各部位吸收的硼量。本研究使用Amberlite IRA - 743树脂控制硼供应，使向日葵植株在营养液中以恒定硼浓度生长，营养液中硼含量充足（46 μmol）或供应有限（0.24、0.40和1.72 μmol）。在生长的营养后期（移栽后25天和35天），分别以0、28、65、120和1200 mmol（每次喷施相当于在100 L·ha⁻¹水中0、0.03、0.07、0.13和1.3 kg B·ha⁻¹）的浓度喷施两次可溶性四硼酸钠（含硼20.8%）。最高硼叶面施肥量导致叶片灼伤，但对植株生长无其他明显有害影响。在缺硼条件下，叶面喷施硼增加了植株的营养和生殖干物质。叶面喷施28 - 1200 mmol硼使最缺硼植株的总干物质增加了三倍多，使最初在营养液中硼含量为1.72 μmol的植株总干物质增加了37 - 49%。在后一种处理中，花盘干物质与对照条件下的相似，但植株总干物质在任何情况下都与对照不同。所有硼叶面喷施量均提高了植株顶部各部位的硼浓度，包括喷施后长出的部位，但叶面喷施硼未提高根系中的硼浓度。以最高喷施量处理的植株花盘中的硼浓度为对照植株的37%至93%。本研究表明，叶面喷施硼对缺硼向日葵植株有益，提高了植株顶部的硼含量，包括在喷施硼后长出的花盘的硼含量。
