Techniques for Achieving High-Quality, High and Stable Yields in Rapeseed through Heavy Application of Boron Fertilizer
Rapeseed is a boron-demanding crop, and especially high-yield, high-quality cabbage-type "double-low" hybrid rapeseed is particularly sensitive to boron deficiency. Boron deficiency at the seedling stage causes slow rooting, dark green and wrinkled leaves, and stunted growth; boron deficiency at the bud-bolting stage causes swelling of the root crown, leaves turning purple to blue-purple, and abnormal flower bud development; boron deficiency at the flowering stage causes plant dwarfing and abnormal pollen...
Rapeseed is a boron-demanding crop, and especially high-yield, high-quality cabbage-type "double-low" hybrid rapeseed is particularly sensitive to boron deficiency. Boron deficiency at the seedling stage causes slow rooting, dark green and wrinkled leaves, and stunted growth; boron deficiency at the bud-bolting stage causes swelling of the root crown, leaves turning purple to blue-purple, and abnormal flower bud development; boron deficiency at the flowering stage causes plant dwarfing, abnormal pollen development, and few seeds set. Practice has proven that applying boron fertilizer in boron-deficient areas generally increases rapeseed yields by 15-30%, and in severely boron-deficient plots, boron application can multiply yields. Increasing boron fertilizer application is an important technical measure for high and stable rapeseed yields.I. Correct Application of Boron Fertilizer
Boron fertilizer can be used as a base fertilizer, topdressing, and foliar fertilizer, but regardless of the method used, application must be based on soil boron content and field growth conditions of rapeseed, applied according to the field and the seedlings:
(1) As base fertilizer: Basal application of boron fertilizer is suitable for soils with moderate or severe boron deficiency. Basal application of boron fertilizer can ensure continuous boron supply and timely meet the boron needs of rapeseed at each growth stage. Before direct seeding or transplanting rapeseed, apply 1-1.5 kg of borax per mu, thoroughly mixed with farmyard manure, chemical fertilizer, or fine soil, and evenly band-applied or hole-applied. When applying, boron fertilizer must never directly contact seeds or seedlings, to avoid burning or inhibiting growth.
(2) Foliar spraying: Foliar spraying of boron fertilizer has the advantages of saving fertilizer and rapid crop absorption, and can also effectively regulate according to the boron requirements of rapeseed at each growth stage. This method is suitable for rapeseed with insufficient basal fertilizer application or soils with moderate, mild, or potential boron deficiency. Foliar spraying should be done early rather than late; the best application periods are the late seedling stage (around flower bud differentiation) and the bolting stage (bolting height 15-30 cm), applied in two rounds (about 15 days apart), spraying 40-60 kg of 0.2% borax solution per mu each time. For seedbeds or the early flowering stage, supplementary boron spraying can be done based on boron deficiency symptoms, with a concentration of about 0.1-0.2% borax solution at 60 kg. Spraying in the evening before dusk on sunny days gives the best results, ideally covering both sides of rapeseed leaves with fine droplets; if rain occurs after spraying, re-spraying is necessary.
II. Issues to Note When Using Boron Fertilizer
1. Strictly control the dosage: Although boron is an essential nutrient element for rapeseed growth, it is a trace element, and the application rate must be strictly controlled. Even in severely boron-deficient soil, the borax dosage per mu should not exceed 2 kg, because excess can cause boron toxicity in crops.
2. Master the spraying timing: Rapeseed requires boron throughout its entire growth stage. Spraying is generally best done at the seedling stage and bud-bolting stage. Foliar spraying of boron fertilizer after rapeseed flowering has no significant yield-increasing effect; spraying boron at the flowering stage is too late and ineffective, while spraying boron during the seed formation stage is basically useless.
3. Use high-quality boron fertilizer: Currently, there are many types of boron fertilizer products sold in the agricultural input market; some have very low actual boron content, and some contain almost no boron. Applying such boron fertilizers will undoubtedly lead to boron deficiency in rapeseed, causing yield reduction or total crop failure. Therefore, boron fertilizer must be purchased from legitimate agricultural input retail stores.
4. Best used in combination with other fertilizers: Applying boron fertilizer alone has no obvious yield-increasing effect. Using boron fertilizer in combination with organic fertilizer and nitrogen, phosphorus, and potassium fertilizers can fully realize the yield-increasing potential.