Responses of wheat and barley genotypes to toxic concentrations of soil boron

Abstract

The growth and yield of seven wheat and two barley cultivars or lines, previously found to show different degrees of boron tolerance under field conditions, were compared in a pot experiment at a range of soil boron treatments . Soil treatments ranged up to 150 mg/kg applied B . Extractable B in soils ranged up to 103 mg/kg . At the highest B treatment seedling emergence was delayed, but the percentage emergence was not reduced . The degree of boron toxicity symptom expression varied between the wheat cultivars and lines, with the two most tolerant, Halberd and (Wq*KP)*WmH)/6/12, displaying the least symptoms .The concentration of boron applied to the soil which produced a significant depression of growth and yield varied between cultivars . For example, the yield of (Wq*KP)*WmH)/6/12 was not affected at the 100 mg/kg applied boron treatment, while the grain yield for (Wl*MMC)/W1/10 was significantly reduced at the 25 mg/kg treatment.There was a linear increase in boron concentration in tillers at the boot-stage with increasing concentration of boron in the soil . The most boron tolerant genotypes had the lowest tissue boron concentrations in each of the treatments . Halberd and (Wq*KP)*WmH)/6/12 had approximately half the boron concentrations of the more sensitive genotypes at the 25 and 50 mg/kg treatments . Differential tolerance of boron within the tissue was also observed . Both Stirling and (WI*MMC)/W1/10 had significantly reduced total dry matter and grain yields at the 25 mg/kg treatment, while the concentrations of boron in boot stage tillers at this treatment were 118 and 100mg/kg, respectively . On the other hand, Halberd and (Wq*KP)*WmH)/6/12 had tissue boron concentrations of 144 and 131 mg/kg, respectively, at the 50 mg/kg treatment but yield was unaffected .The relative responses in the pot experiment, for wheat, were in close agreement with field results . Halberd and (Wq*KP)*WmH)/6/12 had the highest grain yields, with the lowest concentrations of boron in the grain when grown under high boron conditions in the field . In pots these two genotypes proved to be the most tolerant of boron . For barley the advantage in grain yield in the field, expressed by WI-2584 compared with Stirling, was not repeated in pots . WI-2584 was, however, more tolerant than Stirling on the basis of total dry matter production .The results show that useful variation in boron tolerance exists among wheat, and that breeding should be able to provide cultivars tolerant to high levels of boron .

Influence of boron on seed germination and seedling growth of wheat (Triticum aestivum L.)

“…Genotypic variation in susceptibility to B toxicity has been reported (Torun et al, 2006). Paull et al, (1988) reported wide range of intra-specific variation in response to B occurs in a number of crops, including bread wheat (Triticum aestivum L). In addition, seed germination and seedling growth are the most important phases in the life cycle of plant, and are highly responsive to the existing environment.…”

Effects of excess boron on growth, gas exchange, and boron status of four orange scion–rootstock combinations

“…However, since B concentrations in roots are relatively low compared with those in leaves, even at very high levels of B supply, visible symptoms of B toxicity do not develop in roots (Nable et al, 1997). Thus, differential tissue tolerance may play an important role in plant tolerance of such nutritional disorder (Paull et al, 1988). On the other hand, it is likely that B-toxicity effects appear to be loosely correlated with accumulation of high concentrations of B in the shoots, which is a function both of the concentration of B in soil and the time of exposure (Reid, 2007).…”

SCREENING OF THREE SAFFLOWER (Carthamus tinctorius L.) CULTIVARS UNDER BORON STRESS

“…Boron toxicity can affect nearly all crops that have different range of tolerance. Excessive amount of B exert negative effect on number of plant species like reduced photosynthetic efficiency in sunflower leaves [El-Shintinawy 1999], reduced chlorophyll content in cotton older leaves [Ahmed et al 2008], decreased fresh and dry matter and increased B concentration of sunflower shoots [Day 2016a[Day , 2016b, decreased height and shoot growth [Paull et al 1990] and delay in development of wheat [Paull et al 1988], decreased yield of radish [Tariq and Mott 2006], tomato [Eraslan et al 2007], rice [Koohkan et al 2008] and barley [El-Feky et al 2012]. Boron toxicity also has an impact on uptake of other micro or macro elements such as K, Ca, Mg and Na concentration [Tariq and Mott 2006] in plants.…”