Heat stress tolerance in relation to oxidative stress and antioxidants in Brassica juncea.

In the present study fifty genotypes of Brassica juncea were evaluated for heat stress tolerance in terms of biochemical components, in four day old seedlings. Heat shock was given at 45 degrees C for 4.5 hr and thereafter survival percentage, electrolyte leakage and chlorophyll content were estimated. Tolerant genotypes (10) registered survival greater than 65%, moderately tolerant (20) between 35-65% and susceptible (20) less than 35%. Electrolyte leakage was significantly (p < 0.001) higher in susceptible genotypes than in tolerant ones with respect to control seedlings. Chlorophyll content showed no significant variation among the tolerant, moderately tolerant and susceptible genotypes, although it registered a decline in response to heat stress. Lipid peroxidation, assessed by malondialdehyde (MDA) in stressed conditions was 4.66 (MDA g(-1) f. wt. of tissue) in tolerant genotypes, 7.44 (MDA g(-1) f. wt. of tissue) in susceptible genotypes and correlated significantly (r = 0.563) with electrolyte leakage. Increase in POD activity under heat stress was maximum in tolerant class with respect to control. CAT activity showed decrease after heat shock treatment in all the three classes but the decrease was 1.3 fold in tolerant genotypes as compared to 1.6 fold in susceptible genotypes. The non-enzymatic antioxidants glutathione and proline registered a significantly (< 0.01) high value in tolerant genotypes on heat shock treatment in comparison to susceptible genotypes corroborating the role of antioxidants in mitigating the effect of heat stress in Bjuncea. The antioxidants and proline seemed to play role in mitigating the effect of heat stress.

Improvement of conception rate in postpartum flaxseed supplemented buffalo with Ovsynch+CIDR protocol.

The present study was conducted on lactating Murrah buffalo to assess the effect of crushed flaxseed (a source of omega-3 fatty acids) supplementation (300g/100kg bwt/day for 60 days), over and above the routine feed, on luteolytic signal (PGF2α), luteal function (progesterone) and conception rate. In first experiment, on day 50 post-calving, six non-supplemented buffalo were treated to synchronize time of ovulation using an Ovsynch+Controlled Internal Drug Release (CIDR) protocol followed by intravenous oxytocin treatment (OT; 100IU) on day 15 post-ovulation. Blood samples were collected at 15min interval, 1h before to 4h after OT challenge. Thereafter, the same buffalo were supplemented with flaxseed, treated to synchronize time of ovulation starting on day 35 post-supplementation using the same protocol and subjected to OT treatment and blood sampling on day 15 post-ovulation. The PGF2α response was measured as the venous concentration of 13,14-dihydro-15-keto PGF2α (PGFM). The mean hourly concentration of PGFM subsequent to flaxseed supplemented was less (P<0.05) than in the pre-supplementation period at all the occasions. Flaxseed supplementation did not affect plasma fatty acids and other plasma metabolites except for an increase (P<0.05) in plasma cholesterol and plasma alanine transaminase. In the second experiment, 31 buffalo were randomly assigned to a control (n=16) and flaxseed supplemented (n=15) group. The latter group was supplemented with flaxseed starting from day 15 post-calving. On day 50-post-calving, buffalo of both groups were treated to synchronize time of ovulation among animals as described for the first experiment followed by artificial insemination (AI). Post-AI luteal phase plasma progesterone was greater (P<0.05) in the supplemented group compared to controls. Conception rate on day 63 post-AI was 66.7% in supplemented and 31.2% in controls (P<0.05). The present study indicated the beneficial impact of dietary supplementation of crushed flaxseed on conception rate through attenuation of luteolytic signal and improvement in post-breeding luteal profile.