Pearl millet (Pennisetum glaucum (L.) R. Br.) is an important staple cereal cultivated in the arid and semi-arid tropics of Asia and Africa, regions severely affected by malnutrition. Knowledge about the extent of genetic variability and patterns of agro-morphological variation in local germplasm from a target region is an important prerequisite for efficient crop improvement. To assess the potential of Sudanese pearl millet landraces as sources of desirable traits for pearl millet improvement including biofortification, a total of 225 accessions were evaluated in Sudan at three locations for agro-morphological traits and at one location for grain mineral nutrient contents (Fe, Zn, Ca, P, K, Mg, Mn, S, Na, Cu and b-carotene). Genetic variation was highly significant, but relatively limited for some agro-morphological traits (62-78 d to flowering, 119-188 cm plant height and 16-34 cm panicle length), pointing to the potential usefulness of a targeted diversification for these traits. Self-pollinated grain micronutrient contents showed a wide variation: 19.7 -86.4 mg/kg for Fe and 13.5 -82.4 mg/kg for Zn. Significant and positive correlations among most of the nutritional traits were observed; therefore, enhancement of the concentrations of some nutrients will lead to the improvement of other related nutrients. No significant associations were observed between the nutritional and agro-morphological traits, indicating good prospects for simultaneous improvement of both trait categories. No clear patterns of geographic differentiation for specific traits were detected for the Sudanese pearl millet. Nutrient-rich accessions were identified and those with acceptable agro-morphological traits are encouraging materials for future pearl millet biofortification programmes in Sudan.

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High temperature influences both grain yield and end-use quality of wheat. The objectives of this study were to evaluate the performance of selected wheat genotypes under heat stress and to examine the effects of high temperatures during grain filling on grain yield and end-use quality parameters. Fifteen bread wheat genotypes in 2000/2001 and 18 genotypes in 2002/2003 were evaluated under the optimum and latesowing conditions of the irrigated hot environment of the Gezira Research Farm, Wad Medani, Sudan. The genotypes comprised released varieties and elite lines from the Sudanese wheat improvement programme. Data collected included grain yield, grain weight and grain end-use quality including protein content, protein composition, SDS sedimentation values (SDSS) and gluten strength as determined by mixograph analyses. High temperatures significantly decreased grain yield by decreasing grain weight. Although genotypes exhibited variation in magnitude of response, results indicated that high temperature during grain filling increased both soluble and insoluble protein contents, SDSS, mixograph peak height (MPH) and the descending slope at 2 min past peak (MDS). In contrast, mixograph peak time (MPT) and the curve width at 2 min past peak (MCW) were significantly decreased. Flour protein correlated positively with SDSS, MPH and MDS and negatively with MCW. MPT correlated negatively with MDS and positively with MCW. Results indicate that high temperature increased both soluble and insoluble protein contents, SDSS and MPH, and hence the gluten strength, but decreased flour mixing time and tolerance and hence the dough elasticity. Variation observed among genotypes suggests that grain end-use quality could be improved under high temperature conditions utilizing the available variability; however, it might require evaluation under various growing conditions.

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Keywords high shoot/root-zone temperature; net assimilation rate; relative growth rate; specific root weight; wheat; xylem sap flow rate Correspondence I. AbstractHigh temperatures, whether of shoot or root, are reported to affect shoot and root growth of various plant species. The scanty information available on the differential response of wheat genotypes to high shoot and root-zone temperatures triggered this investigation to study the response and adaptation of shoot and root growth of three wheat genotypes to high shoot and root-zone temperatures during early growth stages. Three wheat genotypes; Fang (heat tolerant), Siete Cerros (heat sensitive) and Imam (recent cultivar adapted to a hot irrigated environment) were grown in soil and hydroponically. Three shoot/rootzone temperatures (23/23, 23/35 and 35/35°C for the soil experiment and 22/22, 22/38 and 38/38°C for the hydroponic experiment) were applied at three-leaf growth stage. High root-zone temperature alone or combined with high shoot temperature reduced xylem sap flow rate, root dry weight, root length and root/shoot ratio. Unexpectedly, shoot fresh and dry weights and relative growth rate (RGR) were not significantly affected by the high root-zone temperature except for the susceptible genotype, Siete Cerros, after prolonged exposure in the hydroponic experiment. In contrast, high shoot/root-zone temperature significantly reduced shoot fresh and dry weights from as early as the first week of the hydroponic experiment. The 38/38°C treatment also caused significant reduction in RGR and net assimilation rate during the first 2 weeks, but no significant differences were found during the last 2 weeks compared with 22/22°C. Interesting responses were observed among genotypes in terms of shoot and root dry weights and root/shoot ratio at 38/38°C treatment. The heat-sensitive Siete Cerros showed the least reduction in these traits during the first 2 weeks while the heat-tolerant Fang and Imam responded by greatly reducing their shoot and root weights. The situation was almost reversed with the duration of treatments such that Siete Cerros became the most affected genotype while Fang and Imam were better adapted to high shoot/root-zone temperature. Specific root weight was the exceptional trait that increased under high temperature treatments. Results indicate that despite the reduction in root length and weight observed under high root-zone temperature, shoot growth was not much affected suggesting that the use of suitable cultivar coupled with proper management could alleviate most of high root-zone temperature effects during early growth stages.