Photosynthesis, chlorophyll fluorescence and soluble carbohydrates in sunflower leaves as affected by boron deficiency

Abstract

The effect of various boron levels in the nutrient solution on the growth, boron and chlorophyll content, photosynthesis and chlorophyll fluorescence in the leaves of young sunflower (Helianthus annuus L.) plants was studied under greenhouse conditions. Deficiency of boron decreased the dry matter yield of the roots, shoots and leaves. The content of boron in all analyzed plant parts increased with the increase of boron levels in the nutrient solution, more so in the shoots than in the roots. Leaf area was reduced under boron deficiency as well as the content of chlorophyll in the leaves. The content of analyzed sugars was increased in boron deficient plants, glucose content exhibited the highest increase under boron deficiency.Boron deficiency appreciably decreased photosynthetic oxygen evolution by leaves, the apparent quantum yield and quantum efficiency of photosystem two electron transport. The diminished rate of photosynthesis in boron deficient sunflower leaves could be correlated to the diminished efficiency of electron transport and to the increased content of sugars in the leaves.

The effect of molybdenum and boron in soil on the growth and photosynthesis of three soybean varieties

“…Liu (2000) found that B enhanced photosynthesis efficiency of soybean by membrane maintenance and photosynthesis products translocation and Mo did by chlorophyll stability and enlarging leaf area for photosynthesis. Some studies demonstrated that B excess or deficiency resulted in a decrease of photosynthesis rates in Cucurbita pepo, citrus and sunflower leaves (Lovatt and Bates 1984, Kastori et al 1995, Papadakis et al 2004), but Sage et al (1989) reported that photosynthesis in Streptanthus morrisonii leaves are unaffected by high boron and Zhao and Oosterhuis (2003) found that in the field study, neither soil nor foliar B treatment improved cotton photosynthesis due to sufficient soil B for plant growth (0.2 and 0.3 mg/kg at two study sites). Gupta et al (1991) also observed that treatment with 2 mg/kg Mo (soil dry weight) resulted in a decrease in photosynthesis of 22% in the soybean leaves.…”

Boron deficiency decreases growth and photosynthesis, and increases starch and hexoses in leaves of citrus seedlings

“…Previous studies have shown that B deficiency decreases plant photosynthetic capacity (Kastori et al, 1995;Oosterhuis, 2002, 2003). In mustard (Brassica campestris), decreased rate of CO 2 assimilation appears to result from both decreased Hill reaction activity and low intercellular CO 2 concentration (Sharma and Ramchandra, 1990).…”

Boron influence on concentration of polyols and other sugars in Eucalyptus

“…Valores seguidos pela mesma letra indicam não significância a 5% pelo teste de Tukey. Reductions in the synthesis of sugars were also observed by Kastori et al (1995) in B-deficient sunflower leaves, which were explained as a decrease in their ability to assimilate O 2 and CO 2 . Due to damage caused to the photosynthetic process, starches and sugars were accumulated for a short period in leaves submitted to B deficiency, indicating a reduction in the translocation of photosynthates in sink organs.…”