Chilling stress effects on reproductive biology of chickpea

Chickpea is sensitive to chilling temperatures (<10°C), especially at its reproductive phase leading to floral abortion. The exact causes of reproductive failures are not fully understood. In the present study, we assessed the cold-induced damage to development and functioning of male and female components by growing an early flowering chickpea genotype ICCV 96029 under warm conditions of the glasshouse (control; average maximum and minimum temperature ≥28/15°C) as well as under cold conditions of the field (average maximum and minimum temperature ≤20/10°C during reproductive phase). Low temperature of the field environment restricted the vegetative growth and delayed all the phenological stages in comparison to control plants. Apart from this, it led to some vegetative aberrations like chlorosis, necrosis of leaf tips and curling of whole leaf. The damage to reproductive stage involved abscission of juvenile buds and flowers and abortion of pods. On the whole, pollen development at young microspore stage appeared to be severely affected in stressed conditions compared to the control conditions. Pollen viability was suppressed during stressed conditions (60%) compared to normal plants (95%). Stigma receptivity, in vivo pollen germination and pollen tube growth were inhibited in the stressed plants. Fluorescent studies showed that the stigma either did not show any pollen load or pollen grains did not germinate on its surface in stressed plants. Even when the pollen grains germinated, the pollen tubes rarely grew beyond the proximal region of the style; mostly the pollen tubes were impaired in their growth and did not reach the ovules leading to failure in fertilization. The egg and secondary nucleus in such ovules ultimately disintegrated without fertilizing and hence no seed formation occurred

Stimulatory effect of phosphate-solubilizing bacteria on plant growth, stevioside and rebaudioside-A contents of Stevia rebaudiana Bertoni

The effect of four phosphate-solubilizing bacteria (PSB), (Burkholderia gladioli 10216, Burkholderia gladioli 10217, Enterobacter aerogenes 10208 and Serratia marcescens 10238) as identified on the basis of 16S rRNA gene sequencing was evaluated on plant growth and commercially important glycosides, stevioside (ST) and rebaudioside-A (R-A) of Stevia rebaudiana in pots containing tricalcium phosphate (TCP) supplemented soil. The PSB were isolated from the rhizosphere of S. rebaudiana plants and tested for P-solubilization ability, biocompatibility, indole acetic acid (IAA) and siderophore production. In greenhouse study, treatment of either individual PSB or a consortium (of PSB) resulted in increased plant growth, ST and R-A contents. The stimulatory effect was observed with consortium treatment in plant growth parameters (shoot length, 22.5%; root length, 14.7%; leaf dry weight, 89.0%; stem dry weight, 76.3% and shoot biomass, 82.5%) and glycoside contents (ST, 150% plant−1 and R-A, 555% plant−1) as compared to the un-inoculated plants. Among individual PSB treatments, B. gladioli 10216 showed most promising response in majority of the parameters studied. The root colonization potential of PSB, assayed by RAPD technique, showed the colonization of all PSB isolates, though their extent of colonization varied

Stimulatory effect of phosphate solubilizing bacteria on plant-growth, stevioside and rebaudioside-A contents of Stevia rebaudiana Bertoni

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