Internal Boron Requirement of Young Sunflower Plants: Proposed Diagnostic Criteria

Abstract

In a greenhouse study, a significant increase in sunflower (Helianthus annuus L., cv. Hysun 33) dry matter yield was observed with boron (B) application to a B-deficient (hot water-extractable, 0.23 mg B kg 21 ) calcareous soil of Missa series (Typic Ustochrept). Six rates of B, ranging from 0 to 8 mg B kg 21 soil, were applied as H 3 BO 3 along with adequate basal fertilization of nitrogen (N), phosphorus (P), potassium (K), and zinc (Zn). Four plants of sunflower were grown in each pot; two were harvested after 4 weeks of germination and the other two after 8 weeks. Maximum crop biomass was produced with 1.0 mg B kg 21 , and application of 2.0 mg B kg 21 proved toxic, resulting in drastic yield suppressions. Critical B concentration range for deficiency diagnosis in 4-week-old sunflower whole shoots appears to be 46 -63 mg B kg 21 . However, critical concentration in 8-week-old plants was much less (i.e., 36 mg B kg 2l ), presumably due to a dilution effect. As plant's internal B requirement can vary, in fact manifold, depending on the species, plant part, and plant age, only a relevant criterion can help in diagnosing the deficiency effectively.

Características agronômicas e o estado nutricional de cultivares de girassol irrigado

“…Desses, o B foi o único micronutriente que apresentou tendência similar à da produtividade de aquênios. Pesquisas têm demonstrando que a faixa de concentração crítica de B na folha para o girassol está situada no intervalo de 46 a 60 mg kg -1 de B (Castro & Oliveira, 2005;Rashid & Rafique, 2005). Zobiole et al (2011) Os valores elevados para o teor de B na folha obtidos tanto para variedade como os híbridos, podem ser relacionados ao manejo adequado da irrigação e à alta disponibilidade de B no solo.…”

Boron Increases the Growth and Yield of Mungbean

“…Low concentration of boron bounds the nitrogen fixation in legumes by restricting the nodule formation and nitrogen fixation increased with higher boron concentration (Yakubu et al, 2010). Rashid and Rafique (2005) found the critical B concentration with respect to plant age in weeks. They considered that 1.0 mg B kg -1 of soil produced maximum crop biomass and above that concentration produced toxicity.…”

Field evaluation of a boron recycling fertiliser

“…The results from young leaf analysis in our field experiment (27.4 mg B/kg in control plots) therefore suggest that the sunflower crop was, if at all, only marginally B deficient. Rashid and Rafique (2005) determined B thresholds of 60 and 37 mg B/kg for 4-and 8-week old sunflower shoots in a pot experiment. While our measurement of the whole shoot (ca.…”