The influence of water stress on gas exchange and dry matter accumulation in a wild sunflower (Helianthus agrophyllus T&G) and four cultivated sunflower (Helianthus annuus L.) cultivars (HA 89, RHA 856, 207 A and C) was compared in a glasshouse experiment during 1989-1990. Plants were maintained in a well-watered condition until physiological maturity, while in the drought stress treatment, the irrigation was suspended just before flowering. Measurements were made of leaf photosynthetic and transpiration rates, relative leaf water content, pre-dawn leaf water potential, leaf area index and total dray matter at harvest. Under dray conditions, the water deficit was smaller in the wild species than in the cultivated lines, and photosynthesis and leaf hydration decreased more rapidly with drought in the cultivars. These results, together with the wild sunflower's smaller reduction in dry matter production, its increase in root/shoot ratio under drought at harvest and the unchanged leaf area after 12 days ofdrought, indicate it has a dehydration avoidance mechanism. The hydration avoidance may be due to the larger roots of H. argophyllus and higher root/shoot ratio under drought, compared with the cultivars.

Fifty S1 families of sunflower were evaluated for several seedling traits using three types of selection indicades i.e., Smith-Hazel index, desired gain index and restricted selection index. Six seedling traits namely emergence percentage, emergence index, fresh shoot lenght, fresh root length, fresh root weight, shoot weight and dry shoot weight were included in all the indices as secondary traits. The effiency of three types of selection indices was compared in terms of expected gains expressed in genetic standard deviations. It was observed that desired gain root length was more efficient than Smith-Hazel and restricted selection index as it predicted desirable correlated responses in all the seedling traits

Field experiments were conducted at three North Dakota rainfed environmens to compare the agronomic performance of early maturing dwarf and semidwarf sunflower Heilanthus annuus L. hybrids with a conventional height and maturity hybrid. The study evaluated hybrid response to several plant populations. No differences in seed yierd were observed among hybrids, row spacings, or the hybrid x row spacing and hybrid x population interactions. Increasing plant population, within ttre limits tested in this study, decreased seed yield of all three hybrids. Achene oil 66 consantration was influenced by environments and hybrids. As row spacing decreased achene oil concentration increased. Achene oil concentration increased as plant poputation, within the limits of this study increased. Oil yield (kg ha-1) was heavily influenceo by seed yieid and to a lesser extent by achene oil concentration. Lodging increased when the tallest hybrid was sown at a wide row spacing and high population. In most instances the performance of all three plant types was similar despite major differences in phenological development and plant stature.

L comportement de dix génotypes de tournesol (Herianthus annuus L.) en semis précoces (15 novembre - 15 janvier) a été êtudié aux Domaines Expérimentaux de Douvet -Fès, de Merchouch-Rommani et de Jemâa Shaim-Safi durant la campagne 1989-90. L'objectif principal consistant à rechercher, sous nos conditions, les possibiités des semis d,hiver Permettant d'augmenter le rendement du tournesol jusqu'ici limité considérablemt, en semis habituels de printemps (fin février - mars), par les secheresses estivales. Il ressort des résultats obtenus que les semis d'hiver (novembre - décembre) améliorent d'une façon considérabre les rendements en grains du tournesol sous les conditions marocaines. Ces rendements de l'ordre en 35 à 40qx/ha dépassent de très loin ceux obtenus dans les meilleures situation, soit 20 à.25 qx/ha (region de Douyet.et de Merchouch), et esperes (10 qx/ha) dans le cas d'une éventuelle introduction de cette culture à Jemâa Shahiim, en semis de printemps (fin février - mars). A Douyet, région "froide", les semis d'hiver (15 novembre - 15 décembre) engendrent des cycles longs et limitent la hauteur de la plante, le nombre de feuilles et le diamètre du capitule. ll a été supposé que les différences en hauteur et en nombre de feuilles entre deux dates de semis pourraient constituer un meilleur estimateur de l,effet du froid sur chaque génotype. En dépit de ces contraintes les rendements en grains se sont révélés nettement supérieurs pour les curtivars rardifs. Ces rendements de l'orde de 35 à 40 qx/ha sont deux fois plus élevés que ceux obtenus en semis de janvier où les variétés précoses I'emportent (24qx/ha). A Merchouch, région à hiver relativement clément, les caractères observés sont generalement les memes dans les trois dates de semis et traduisent ainsi la tres bonne vigueur exprimée par l'ensemble des génotypes. Cependant res meileurs rendements en grains enregistrés uniquement à la première date de semis expriqueraient que celui-ci est affecté, au cours des deux dernière dates, au moment de la formation de la graine. La secheresse de fin de rycle aurait limité leur remplissage. A Jemâa Shaïm, région "aridè" à hiver doux, seure Ia première date de semis a permis une expression meilleure des caractères parl'ensemble des génotypes. Ainsi les semis d'au dela cette date sont inespérés et la période novembre - débùt decémbre constituerait le temps idéal d'introduction du tounesol dàns cette région où cerlui-ci a éte marginalise jusqu a present.

Se establecid un experimento con 60 hibridos de girasol en dos localidadesl uno en el norte y otro en el centro del €stado de Tamaulipas, México, en los campos Experimentales de Rio Bravo y el Tablero del Instituto-Nacional de Investigaciones Forestales y Agropecuarias (INIFAP-TAM). Los progenitores 5 lîneas estériles cms y 12 lîneas R formadores de estos hybridos, fueron obtenidos en Rio Bravo. La siembra se eealizd en angosto de 1990 y en un diseno oxperimental de lâtice simple 9x9 con 4 repeticiones. El objetivo fue evaluar la aptitud combinatoria general (ACG) y especifica (ACE) para rendimienio de grano y contenido de aceite delas lineas involucradas. Cuatro progenitores macho mostrarôn buéna ACG para rendimiento de grano y cinco para contenido de aceite. Las hembras 285 y 486 mantuvieron buena ACG en ambas caracteristicas. La ACE mostro efectos de accidn génica no aditiva para rendimiento de grano y para contenido de aceite los efectos fueron priicipalmente aditîvos. se detectaron varios hfbridos con alta produccion de grano y aceite para las condiciones de ambas localidades.

Introduction of sunflower varieties and hyhrids is the best protection against the sunflower moth. Sunflower resistance to the pest depends on the presence of the phytomelanin layer in the pericarp. An analysis of 23 wild sunflower species with a saturated solution of bichromate (K2CrO7) and sulphuric acid (H2SO4) has shown that the perennial species tested have a thicker average phytomelanin layer that the annual species. Differences have also been found between the species as well as between populations of individual species. Of the 84 populations tested, only 6 of these had the phytomelanin layer 100% of the achenes tested.

Immature zygotic hybrid embryos of sunflower were cultured on MS medium supplemented with BAP in the range of 0.5 02.5 mg/l. Adventitious shoot buds were induced on the hypocotyl region of the immature embryos of a cross between a commercial male sterile line (234A) and a restorer line (RF1). These adventitious buds were grown to shoots, rooted and transferred to the field. Fertile plants were obtained which set seeds in approximately two and a half months from initiation. This method will help shorten generation time an therefore can be profitably used in sunflower breeding programmes.

The research evaluates four methods of pollination: 1) bees, 2) open pollination, 3) hand polination using mixted pollen,4) self-pollination. The test included 11 populations of wild H. annuus and six populations of H. petiolais ssp. petiolaris. The method of controlled pollination with bees produced significantly higher numbers of achenes than the other three method in all but two. H. annuus populations. With H.petiolaris, the controlled bee pollination produced a lower numbers of achenes than the open pollination. After 50 days in cage, the bee swarms stopped multiplying, i.e., the queens stopped ovipositing and the workers threw eggs out of the cells. After the end of pollination, the swarms were fewer in number than at the beginning of pollination.

Several hybrids of sunflower (Helianthtus annuus L.) were evaluated for resistance to grey mould, caused by Botrytis cinerea Pers., and their potentials as possible sources of resistance were determined. Cultivars were subjected to nitural infection and inoculation in field and growth chamber experiments, respectively. The results obtained showed highly significant (P<0.001) differences in disease severity between cultivars. However, no genotype was completely resistant. A number of cultivars express low levels of susceptibility, particularly the hybrid 'NS-H-45'. The evaluation of S1 progeny and single-plant-progenies of this cultivar revealed that selection for low level of susceptibility and hence breeding for resistance is possible.

Nutrient assimilation and metabolism in sunflower leaves were examined in both btealthy and Alternaria helianthi infected plants. An increase in the total nitrogen and accumula tion of ammonia was observed in the Ahemaia infected leaves. The nitrate accumulation following infection was found to be non-significant. A significant increase in total phosphorus was observed in infected leaves whereas the available phosphorus contents was reduced drastically. The deamination of aspartic acid, glutamic acid, tyiosine and arginine in vivo was found to be significantly higher in infected leaves than healthy ones. The nitrite and nitrate reductase activitieswere found to be higher in infected leaves. Whereâs the ratio ofchlorophyll a/b was higherin healthy leaves. The soluble sugar contentwas observed to be more in infectêd than the healthy leaves ofsunflower. The possible explanations for these alterations in nutrient metabolism of sunflower leaves infected with Alternaria have been discussed.

Afield survey was carried out during 1991 to assess the distribution and incidence of various sunflower diseases in different agro-ecological zones of Pakistan. In total, 1400 acres of sunflower crop from 45 localities were inspected and 9 fungal and one bacteril disease were recorded. The number of diseases recorded differed among ihe regions and their distribution and incidence broadly corresponded to the intensity of sunflower production. Alternaria leaf spot and charcoal rot were observed.in all the regions and were most severe with highest incidence of 80 and 90 percent, respectively. Powder mildew and bacterial rot were also found to be emerging pathological problems particularly in the Punjab province.