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Interactive effect of salt (NaCl) and nitrogen form on growth, water relations and photosynthetic capacity of sunflower ( Helianthus annum L.)
Author(s) -
ASHRAF M.
Publication year - 1999
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1999.tb00881.x
Subject(s) - sunflower , biology , helianthus , photosynthetic capacity , photosynthesis , helianthus annuus , salt (chemistry) , nitrogen , agronomy , botany , chemistry , physics , quantum mechanics
SUMMARY The effects of the ammonium (NH 4 + ) and nitrate (NO 3 ‐ ) forms of nitrogen and NaCl on the growth, water relations and photosynthesis performance of sunflower ( Helianthus annuus L.) were examined under glasshouse conditions. Eight‐day‐old plants of cv. Hisun 33 were subjected for 21 days to Hoagland's nutrient solution containing 8 mol m ‐3 N as NH 4 + or NO 3 ‐ , and salinised with 0, 60, or 120 mol m ‐3 NaCl. Fresh weights of shoots and roots, and leaf area of NO 3 ‐ supplied non‐salinised plants were significantly greater than those of NH 4 + ‐supplied non‐salinised plants. But addition of NaCl to the rooting medium of these plants had more inhibitory effect on the growth of NO 3 ‐ ‐supplied plants than on NH 4 + ‐supplied plants. Both leaf water and osmotic potentials of plants grown with NH 4 + were lower than those of plants given NO 3 ‐ under both non‐saline and saline conditions. Chlorophylls a and b concentrations were higher in plants grown with NH 4 + than N0 3 ‐ ‐supplied plants at the lower two levels of salinisation. The rate of photosynthesis in plants was considerably higher in non‐salinised plants grown with NO 3 ‐ than with NH 4 + , but with increase in salinisation the photosynthesis rate decreased in NO 3 ‐ ‐supplied plants, but not in those given NH 4 + . The rate of transpiration was increased significantly by salinisation in NO 3 ‐ ‐supplied plants, but not consistently so in NH 4 + ‐supplied plants. The stomatal conductances were much higher in plants given NO 3 ‐ than with NH 4 + when grown under non‐saline conditions, but not when salinised. As a consequence, water‐use efficiency in NO 3 ‐ ‐supplied control plants was better than in NH 4 + ‐supplied under non‐saline conditions, but worse under saline conditions. The different forms of nitrogen and the addition of NaCl to the growing medium did not affect the relative intercellular concentrations of CO 2 (C i /C a ). Overall, the NH 4 + form of nitrogen inhibited the growth of sunflowers under non‐saline conditions, but NO 3 ‐ and NaCl interacted to inhibit growth more than did NH 4 + under saline conditions.