RELATIONSHIP BETWEEN PHOTOSYNTHETIC CARBON EXCHANGE-RATE, SPECIFIC LEAF MASS AND OTHER LEAF CHARACTERISTICS IN CHICKPEA GENOTYPES

Thirteen chickpea (Cicer arietinum L.) genotypes, raised in the field, were screened for carbon exchange rate (CER), related leaf characters and dry matter production throughout the season. Seasonal pattern of the CER and related characters were similar in all genotypes. CER show ed two peaks, one at the late vegetative phase and the other at the pe ak pod filling phase. Stomatal resistance (r(s)) and specific leaf mas s (SLM) increased in the successively formed leaves while nitrogen con centration tended to decline, especially in later-formed leaves. Nitro gen (N) content per unit area, however, remained relatively constant t hroughout the season. Significant genotypic variabilities were observe d in CER and related characters as well as in total dry matter accumul ated at harvest. Seasonal means of CER ranged from 12.5 in HG 1765B to 18.4 mu mol CO2 m(-2) s(-1) in BG 315, SLM from 5.1 in HG 1765 to 6.5 mg dry weight cm(-2) in BG 315, r(s) from 1.31 in BG 315 to 1.92 s cm (-1) in Hyb 16-3, leaf N content from 122.6 in HG 1765B to 172.1 mmol m(-2) in BG 315 and total dry matter at final harvest from 9.9 in HG 1 765B to 34.9 g plant(-1) in K4. Seasonal means of CER were positively correlated with SLM, N content per unit area and final harvest dry mat ter. Stomatal resistance was negatively correlated with CER and final harvest dry matter. The results indicate that although CER is the best selection criterion for higher dry matter production in chickpea, it is possible to use SLM as an indirect selection criterion for CER in t his crop. However, such a selection based on SLM involves the risk of elimination of high N-use efficiency genotypes.