ABSTRACT

Boron (B) fertilization management of alfalfa, as perennial crop, requires to identify its sensitivity to B and its nutrients status after B supply for different forage harvests. The response of alfalfa to B supply, when grown on a Mediterranean sandy soil, was evaluated at different cuts. The native soil B content was around 0.15 mg kg⁻¹, which was considered as B deficient. 19 cuts were evaluated in container experiment during three successive production seasons: 2016 (5 cuts), 2017 (7 cuts), and 2018 (7 cuts). Six soil B supplies were tested: 0 (control), 0.2, 0.5, 1, 5, and 10 mg kg⁻¹. B was added in the sodium form. It was split equally between sowing and after the first cut for each rate. The results revealed that B deficiency symptoms did not induce a negative impact on total biomass production and protein content. Shoot B content of all cuts increased with increasing B rates. The lowest shoot B levels (<35 mg kg⁻¹) were recorded in control after five successive cuts. B uptake for each cut can be predicted using the regression model: y (mg kg⁻¹ of soil) = 0.018 x–0.01 z + 0.14 (adjusted R2 = 0.61) where x = soil B supply (mg kg⁻¹) and z = cut number during growing seasons (from 1 to 19). The residual soil B was less than 0.5 mg kg⁻¹, after 19 cuts, for different B rates. The results suggest that alfalfa seems not to be affected by B deficiency particularly during the first 3 years of production in sandy soil.

摘要

作为多年生作物的紫花苜蓿（B）的硼（B）施肥管理，需要确定其对B的敏感性以及在不同草料收获后供应B后对B的营养状况。当在地中海沙质土壤上种植苜蓿时，对苜蓿对硼供应的反应进行了评估。天然土壤中的B含量约为0.15 mg kg ^-1，这被认为是B缺乏。在三个连续的生产季节中，通过容器实验对19个切块进行了评估：2016年（5个切块），2017年（7个切块）和2018年（7个切块）。测试了六种土壤B供应：0（对照），0.2、0.5、1、5和10 mg kg ^-1。B以钠形式加入。每种播种的播种期与第一次采收后均等。结果表明，B缺乏症状并未对总生物量生产和蛋白质含量产生负面影响。随着B比率的增加，所有切块的B含量均增加。在连续切割五次后，对照中记录了最低的芽B水平（<35 mg kg ^-1）。可以使用回归模型预测每次切割的B吸收量：y（土壤的mg kg ^-1）= 0.018 x–0.01 z + 0.14（调整后的R2 = 0.61），其中x =土壤B的供给量（mg kg ^-1）和z =在生长季节减少的数量（从1到19）。残留土壤B小于0.5 mg kg ^-1，在削减19次之后，适用于不同的B费率。结果表明，苜蓿似乎不受硼缺乏的影响，特别是在沙质土壤生产的前三年中。