Can soil plant analysis development values predict chlorophyll and total Fe in hybrid poplar?

摘要

Iron chlorosis caused by an elevated soil pH remains an important selection criteria in evaluating hybrid Populus trials in northwest New Mexico. Compared to expensive extraction methods or visual ranking scales, the soil plant analysis development (SPAD) chlorophyll meter is a handheld tool that objectively indicates leaf color. SPAD calibration curves pertaining to Fe status in Populus leaves were developed for two clones: NM-6 (Populus nigra × Populus maximowiczii) and OP-367 (Populus deltoides × Populus nigra). Hybrids were grown in the greenhouse in a sandy loam soil of pH > 8 and the same soil amended with composted biosolids enriched with 420 mg kg−1 Fe. SPAD measurements related to foliar Fe as follows: r 2 = 0.72 for NM-6 and r 2 = 0.58 for OP-367. SPAD measurements correlated with total chlorophyll as follows: r 2 = 0.66 for NM-6 and r 2 = 0.85 for OP-367. Based on the total chlorophyll content (supported with foliar element data), Fe sufficiency threshold values from SPAD measurements were estimated in these two clones. Keywords Populus hybrids - Iron chlorosis - Biosolids - SPAD meter