Syed Aiman Hasan

Growth of tomato (Lycopersicon esculentum) in response to salicylic acid under water stress

Abstract Plants of Lycopersicon esculentum L. cv. K-25 were subjected to water stress by withholding water for 10 days at 20 (WS I) and 30 (WS II) days after sowing (DAS). Seedlings were sprayed with double distilled water (DDW) or 10−5M salicylic acid (SA) at 45 DAS. The water stress at earlier stage of growth (20 day stage) was more inhibitory as compared to the later stage (30 day stage). The plants exposed to water stress exhibited a significant (p<0.05) decline in photosynthetic parameters, membrane stability index (MSI), leaf water potential, activity of nitrate reductase (NR), carbonic anhydrase (CA), chlorophyll and relative water content (RWC). A follow-up treatment with SA protected against the stress generated by water and significantly improved the above parameters. However, proline content and antioxidant enzymes increased under drought as well as under SA treatments.

Effect of Salicylic Acid on Salinity-induced Changes in Brassica juncea

Seeds of Indian mustard (Brassica juncea (L.) Czern. et Coss.) were exposed to 0, 50, 100 and 150 mmol/L NaCl for 8 h and seeds were sown in an earthen pot. These stressed seedlings were subsequently sprayed with 10 micromol/L salicylic acid (SA) at 30 d and were sampled at 60 d to assess the changes in growth, photosynthesis and antioxidant enzymes. The seedlings raised from the seeds treated with NaCl had significantly reduced growth and the activities of carbonic anhydrase, nitrate reductase and photosynthesis, and the decrease was proportional to the increase in NaCl concentration. However, the antioxidant enzymes (catalase, peroxidase and superoxide dismutase) and proline content was enhanced in response to NaCl and/or SA treatment, where their interaction had an additive effect. Moreover, the toxic effects generated by the lower concentration of NaCl (50 mmol/L) were completely overcome by the application of SA. It was, therefore, concluded that SA ameliorated the stress generated by NaCl through the alleviated antioxidant system.

Brassinosteroids protect photosynthetic machinery against the cadmium induced oxidative stress in two tomato cultivars

The present study was conducted with an aim to gain better insight of brassinosteroid generated response on the effects of cadmium on photosynthetic machinery and active oxygen metabolism in two tomato cultivars (K-25 and Sarvodya). These tomato cultivars were subjected to graded cadmium levels in soil (0, 3, 6, 9 or 12 mg kg(-1) soil) with their foliage being sprayed with 0 or 10(-8) M of 28-homobrassinolide/24-epibrassinolide (HBL/EBL) at 59 d stage. The results suggested that photosynthetic parameters, leaf water potential and activity of several enzymes (nitrate reductase and carbonic anhydrase) decreased significantly in both the cultivars, to a lesser extent in K-25 than Sarvodya with the increasing levels of cadmium in the soil. However, the activity of antioxidant enzymes and proline content increased in response to metal treatment as well as the application of brassinosteroids (HBL/EBL). Overall, exogenous application of brassinosteroids improved the activity of photosynthetic machinery and that of antioxidant defense system in both the cultivars, and also nullified the damaging effect of metal on these parameters.

Screening of salt-tolerant genotypes of Brassica juncea based on photosynthetic attributes

Abstract The present experiment was conducted to evaluate salt tolerance in varieties of Indian mustard (Brassica juncea). Sterilized seeds were grown under natural environment in pots containing soil amended with 1.4 (control), 2.8, 4.2 and 5.6 dSm−1 NaCl and sampled at 30 days after sowing. Growth was recorded in terms of length, fresh mass, dry mass and leaf area of plants, which was drastically reduced in Chapka Rohini, while there was little effect of NaCl treatment on Varuna. In Chapka Rohini, a rise in the level of proline was observed which followed the decline in protein content. The declines in net photosynthesis and other related parameters have been attributed to this decline. From the results, it could be suggested that Varuna is salt-tolerant while Chapka Rohini is the salt-sensitive variety of mustard among the screened genotypes. Photosynthetic capacity is a major factor in conferring the salt-sensitiveness and tolerance in plant varieties.

IAA and 4‐Cl‐IAA Increases the Growth and Nitrogen Fixation in Mung Bean

A commonly occurring auxin indole‐3‐aceticacid (IAA) and a rarely occurring chlorosubstituted auxin (4‐Cl‐IAA) were compared for their impact on growth and nitrogen metabolism in mung bean for the first time. The plants were generated from healthy and Rhizobium coated seeds in earthen pots. The seedlings at 7 and/or 14 days were percolated with 0, 10−10, 10−8, or 10−6 M of IAA or 4‐Cl‐IAA. The plants were sampled at 30 days after sowing (DAS) to assess the growth and various biochemical characteristics. The auxins significantly enhanced the growth (length and dry mass of shoot and root), nodule fresh mass, nitrogenase activity in fresh nodules, leaf carbonic anhydrase activity, chlorophyll content, and rate of photosynthesis. The effect of the auxins lasted up to the harvest where the seed yield, 100 seed mass, and number of pods per plant were significantly affected by the auxins. At a moderate concentration (10−8 M), 4‐Cl‐IAA generated the best response. However, a comparable response was generated by the higher concentration (10−6 M) of 4‐Cl‐IAA. The application of the hormone twice (at 7 and 14 DAS) was much more effective than single application (at 7 or 14 DAS). It was concluded that IAA and 4‐Cl‐IAA improved the growth and nitrogen fixation in mung bean. The 4‐Cl‐IAA proved more effective than IAA.

Screening of tomato (Lycopersicon esculentum) cultivars against cadmium through shotgun approach

Abstract Ten tomato (Lycopersicon esculentum) cultivars K-25, K-21, NTS-9, Kaveri, NBR-Uday, Swarnodya, Sarvodya, NBR-Uttam, Malti, and S-22 were soaked (i.e., shotgun approach) in various concentrations of CdCl2 (0.0, 50, 100 or 150 µM) for variable durations (0, 4, 8, or 12 h) with the aim of finding out the degree of tolerance. The data obtained at 30 days after sowing indicated that all the growth and photosynthetic characteristics were decreased significantly as the concentration of cadmium increased irrespective of soaking duration. All the cultivars differ widely in their ability to tolerate the Cd stress. The variety S-22 could not survive in the presence of any Cd concentrations, the variety Sarvodya, NBR-Uttam, and Malti experienced severe damage; however, the variety Kaveri, NBR-Uday and Swarnodya were moderately affected. Moreover the variety K-25, K-21 and NTS-9 showed the maximum resistance to cadmium concentrations.

Photosynthetic variation and yield attributes of two mustard varieties against cadmium phytotoxicity

Abstract Excess cadmium accumulation in shoot decreases the photosynthetic attributes and the activity of carbonic anhydrase (CA; E.C. 4.2.1.1) thereby retarding plant growth metabolism, in a cultivar dependent manner. Two mustard (Brassica juncea) varieties were treated with increasing cadmium doses (0, 25, 50 or 100 mg CdCl2 kg−1 of soil) in the soil in a net house. The photosynthetic features, activity of CA, and the yield attributes were recorded in association with morphological characters. A clear-cut difference in these features was noted among the varieties, where Varuna excelled in its resistance to the cadmium toxicity with better growth and yield, at harvest.