Physiological aspects of yield variation among seven groundnut genotypes cultivated under rain-fed conditions

This experiment was conducted at two locations, in North Kordofan under rain fed conditions for two consecutive seasons (2005/06 and 2006/07), to study the physiological aspects of yield variation among seven groundnut (A raichis hypogaea L.), genotypes (Barberton, Sodiri, Gubiesh, ICGV89171, ICGV93296, ICGV86744 and ICGV92126).The tested varieties were arranged in a randomized complete block design with four replications. Several morpho-physiological traits such as crop growth rate (CGR), relative growth rate (RGR), specific leaf area (SLA), net assimilation rate (NAR), leaf area (LA), leaf area (LAI), nitrogen fixation traits and yield and its component were measured. Samples were collected at two weeks interval between 20 and 80 days after planting. The results of the combined analysis showed that there were no significant (p =0.05) differences among varieties for the measured morpho-physiological traits throughout the season. Mean seasonal pattern of these traits indicated that the maximum LAI, SLA, CGR, RGR and NAR were attained 65 days after planting. All these traits increased rapidly at the early period of growth reaching their maximum at 65 days after planting and declined towards harvest i.e. at 80 days after planting. Numbers of primary branches, reproductive efficiency and nodules weight were not significantly different among genotypes, while secondary branches and number of nodules were significantly different. Significant varietal differences were observed for pod yield, hay yield, hundred seed weight and pod maturity, while differences in number of pods per plant, seeds per pod, shelling percentage and harvest index were not significant. The highest pods yields of 551, 545 and 540 kg/ ha were recorded by Barberton, ICGV89171 and Sodiri, respectively. The lowest yield of 376 kg/ ha was recorded by ICRISAT line ICGV93296. Barberton recorded the best hay yield followed by ICRISAT lines. Sodiri and Gubiesh, the released varieties recorded a high hay yield of more than 900 kg/ ha. Hundred seed weight of all varieties, except ICGV93296, ranged between 35 and 38 grams. Differences among harvest index were not significant. Harvest index of all genotypes ranged between 31 and 35 %. Generally, there were significant and positive correlations between physiological traits across the season. High significant and positive correlations were observed for pod yield with number of pods per plant, hundred seed weight and harvest index. Results of this study revealed that the best yielding varieties, that recorded more than 500 kg/ha pod yield were characterized by high pod maturity and relatively high reproductive efficiency