Growth Period Management Techniques for Gladiolus Cut Flower Open-Field Production (Part 2)
Growth Period Management in Open-Field Production Technology for Gladiolus Cut Flowers (Part 2)
2. Fertilizer Application Rate
The fertilizer application rate for the planting site should be determined according to soil conditions, and attention should also be paid to the effect of pH on fertilizer efficiency. When the soil is alkaline, calcium superphosphate will be fixed and not easily absorbed by roots; if the soil is acidic, phosphorus is easily leached, leading to phosphorus deficiency. When pH is below 5, fluorine toxicity is easily caused. Fertilizer loss is faster in sandy soil, while the opposite is true for clay soil. Fertilizer loss is also relatively serious during the rainy season.
Of course, it is best to evaluate the plant's fertilizer requirements by measuring the mineral element content in the plant tissues. For producers, judging fertility conditions by observing the growth of gladiolus plants is also an auxiliary method. When nitrogen fertilizer is insufficient, leaf color becomes lighter or even yellow, often causing poor plant growth, delayed flowering, and a reduced number of florets. Supplementing nitrogen fertilizer will promote an increase in flower spike weight and corm yield. If the leaves are dark green and relatively weak, there may be excessive nitrogen fertilizer, which will cause flower spikes to be soft and fragile, shorten the flowering period, and increase the chance of disease infection. When potassium fertilizer is insufficient, the young leaves turn yellow between the veins, the plant and flower stems become shorter, and flowering is delayed. Potassium dihydrogen phosphate can be used for foliar spraying. Sufficient potassium fertilizer helps improve corm quality and the number of small cormels. With phosphorus deficiency, young leaves are dark green while old leaves appear purple; potassium dihydrogen phosphate or calcium superphosphate can be applied as a foliar spray. Phosphorus fertilizer also helps the absorption of nitrogen fertilizer.
During the growth and development of gladiolus, some trace elements are sometimes also needed, such as calcium, manganese, magnesium, boron, iron, copper, and zinc. Calcium deficiency will cause inflorescence differentiation to stop or decrease, or even cause flower buds to wither. This phenomenon is prone to occur in soft water areas and can be supplemented by spreading lime or spraying calcium nitrate on the leaves. Iron deficiency will cause chlorosis between the leaf veins, which is prone to occur in new leaves, and in severe cases will cause the leaves to turn yellow-white. Iron deficiency is most likely to occur in alkaline soil and can be improved by applying chelated iron (Fe-EDTA, etc.) to increase the availability of iron. Magnesium deficiency causes chlorosis at the leaf margins of old leaves and yellowing of the plant. However, excessive magnesium increases the symptoms of calcium deficiency in the plant. Boron deficiency causes leaves to become thick and brittle, leaf margins to split easily, deformation, and dwarfed inflorescences. However, excessive boron will cause leaf scorch. Trace elements can be supplemented by soil application or foliar spraying.
Overall, gladiolus does not require a very large amount of fertilizer and is sensitive to salt content, so fertilizer should be applied at the right time and in the right amount, with attention paid to the effects of chloride and fluoride ions. Maintaining nutritional balance among various fertilizer elements, including some trace elements, will achieve better results and ensure the excellent quality of cut flowers.
3. Lodging Prevention
Gladiolus plants are tall, reaching 1.2-1.5 m. In the later growth stage, as the inflorescence grows, the plant's center of gravity rises, and in wind and rain it is prone to lodging. After lodging, the flower stems bend upward, affecting cut flower quality. Therefore, in production, nylon nets or plastic nets are often set up, and the nets are continuously raised as the plants grow, so as to keep the plants growing upright. In addition, when gladiolus replaces its new corm, the new corm is above and the new roots (contractile roots) are also close to the ground surface, while in the middle and late stages of its growth and development it mainly relies on the function of the new roots. When planted shallowly, the plant has poor drought resistance, which can very easily affect flower development. Therefore, some people have tested deep planting at 20-30 cm and found that it is beneficial to plant growth, and the weight of the new corm increases and the internodes of the corm elongate. Others have also experimentally proven that earthing up during cultivation can also play the role of deep planting. After earthing up three times at the sprouting stage, four-leaf stage, and flowering stage, the plants are not only robust and do not lodge, but the new corms also increase in weight and have a tall, rounded shape. Moreover, tests have shown that corms from deep planting contain less endogenous growth-inhibiting substances than those from shallow planting.
The fertilizer application rate for the planting site should be determined according to soil conditions, and attention should also be paid to the effect of pH on fertilizer efficiency. When the soil is alkaline, calcium superphosphate will be fixed and not easily absorbed by roots; if the soil is acidic, phosphorus is easily leached, leading to phosphorus deficiency. When pH is below 5, fluorine toxicity is easily caused. Fertilizer loss is faster in sandy soil, while the opposite is true for clay soil. Fertilizer loss is also relatively serious during the rainy season.
Of course, it is best to evaluate the plant's fertilizer requirements by measuring the mineral element content in the plant tissues. For producers, judging fertility conditions by observing the growth of gladiolus plants is also an auxiliary method. When nitrogen fertilizer is insufficient, leaf color becomes lighter or even yellow, often causing poor plant growth, delayed flowering, and a reduced number of florets. Supplementing nitrogen fertilizer will promote an increase in flower spike weight and corm yield. If the leaves are dark green and relatively weak, there may be excessive nitrogen fertilizer, which will cause flower spikes to be soft and fragile, shorten the flowering period, and increase the chance of disease infection. When potassium fertilizer is insufficient, the young leaves turn yellow between the veins, the plant and flower stems become shorter, and flowering is delayed. Potassium dihydrogen phosphate can be used for foliar spraying. Sufficient potassium fertilizer helps improve corm quality and the number of small cormels. With phosphorus deficiency, young leaves are dark green while old leaves appear purple; potassium dihydrogen phosphate or calcium superphosphate can be applied as a foliar spray. Phosphorus fertilizer also helps the absorption of nitrogen fertilizer.
During the growth and development of gladiolus, some trace elements are sometimes also needed, such as calcium, manganese, magnesium, boron, iron, copper, and zinc. Calcium deficiency will cause inflorescence differentiation to stop or decrease, or even cause flower buds to wither. This phenomenon is prone to occur in soft water areas and can be supplemented by spreading lime or spraying calcium nitrate on the leaves. Iron deficiency will cause chlorosis between the leaf veins, which is prone to occur in new leaves, and in severe cases will cause the leaves to turn yellow-white. Iron deficiency is most likely to occur in alkaline soil and can be improved by applying chelated iron (Fe-EDTA, etc.) to increase the availability of iron. Magnesium deficiency causes chlorosis at the leaf margins of old leaves and yellowing of the plant. However, excessive magnesium increases the symptoms of calcium deficiency in the plant. Boron deficiency causes leaves to become thick and brittle, leaf margins to split easily, deformation, and dwarfed inflorescences. However, excessive boron will cause leaf scorch. Trace elements can be supplemented by soil application or foliar spraying.
Overall, gladiolus does not require a very large amount of fertilizer and is sensitive to salt content, so fertilizer should be applied at the right time and in the right amount, with attention paid to the effects of chloride and fluoride ions. Maintaining nutritional balance among various fertilizer elements, including some trace elements, will achieve better results and ensure the excellent quality of cut flowers.
3. Lodging Prevention
Gladiolus plants are tall, reaching 1.2-1.5 m. In the later growth stage, as the inflorescence grows, the plant's center of gravity rises, and in wind and rain it is prone to lodging. After lodging, the flower stems bend upward, affecting cut flower quality. Therefore, in production, nylon nets or plastic nets are often set up, and the nets are continuously raised as the plants grow, so as to keep the plants growing upright. In addition, when gladiolus replaces its new corm, the new corm is above and the new roots (contractile roots) are also close to the ground surface, while in the middle and late stages of its growth and development it mainly relies on the function of the new roots. When planted shallowly, the plant has poor drought resistance, which can very easily affect flower development. Therefore, some people have tested deep planting at 20-30 cm and found that it is beneficial to plant growth, and the weight of the new corm increases and the internodes of the corm elongate. Others have also experimentally proven that earthing up during cultivation can also play the role of deep planting. After earthing up three times at the sprouting stage, four-leaf stage, and flowering stage, the plants are not only robust and do not lodge, but the new corms also increase in weight and have a tall, rounded shape. Moreover, tests have shown that corms from deep planting contain less endogenous growth-inhibiting substances than those from shallow planting.