. 2004. Canola and mustard response to short periods of temperature and water stress at different developmental stages. Can. J. Plant Sci. 84: 697-704. Seed yield of Brassica crops in semiarid environments can be increased by minimizing the crops' exposure to high temperature and water stress that often occurs during the growing season. A growth chamber study was conducted to determine the effect of short periods of high temperature and water stress at different developmental stages on seed yield and yield components of Brassica crops. Two canola-quality Brassica juncea 'PC98-44' and 'PC98-45', a Brassica napus canola 'Quantum', and a B. juncea oriental mustard 'Cutlass' were grown under 20/18°C day/night temperatures with photoperiod of 16/8 h light/dark. High (35/18°C) and moderate (28/18°C) temperature stress was imposed for 10 d during bud formation, flowering, and pod development. Low (90% available water) and high (50% available water) water stress was imposed in combination with the temperature treatments. On average, the 35/18°C stress reduced main stem pods by 75%, seeds pod -1 25%, and seed weight 22% from the control. Seed yield per plant was reduced by 15% when plants were severely (35/18°C) stressed during bud formation, 58% when stressed during flowering, and 77% when stressed during pod development. Plants stressed at earlier growth stages exhibited recovery, whereas stress during pod development severely reduced most of the yield components. Effect of water stress on seed yield was minimal regardless of crop developmental stage. The four Brassica cultivars responded similarly to water stress. In response to temperature stress, B. juncea produced greater number of pods per plant but had a great rate of pod infertility than B. napus. Seed yield of B. juncea in semiarid environments can be increased by improving pod fertility, whereas the seed yield of B. napus can be increased by improving pod production and retention. On peut accroître le rendement grainier des espèces du genre Brassica en milieu semi-aride en réduisant le plus possible l'exposition des plantes aux températures élevées et au stress hydrique fréquents durant la période végétative. Les auteurs ont effectué une expérience en phytotron afin de préciser les conséquences de brefs stress thermique et hydrique à divers stades de croissance sur le rendement grainier et sur divers paramètres du rendement des espèces du genre Brassica. Pour cela, ils ont cultivé deux variétés de Brassica juncea de qualité canola (PC98-44 et PC98-45), le canola (B. napus) Quantum et la moutarde joncée (B. juncea) Cutlass à la température diurne/nocturne de 20/18°C durant une photopériode de 16/8 h de clarté/obscurité. Ils ont ensuite soumis les plantes à un stress thermique intense (35/18°C) ou modéré (28/18°C) pendant 10 jours lors de la formation des bourgeons, de la floraison et de la formation des gousses. Au stress thermique s'ajoutait un faible (90 % d'eau disponible) ou fort (50 % d'eau disponible ) stress hydrique. En moyenne, un stress thermique de 3...

Minimizing the exposure of an annual crop to abiotic stresses may increase seed yield. A study was conducted to determine the effect of high temperature stress during reproductive development on pod fertility, seed set, and seed yield of chickpea (Cicer arietinum L). 'Myles' desi and 'Xena' kabuli chickpea were grown in a controlled environment under 20/16°C day/night air temperatures (control). High (35/16°C) and moderate (28/16°C) temperature stresses were imposed for 10 d during early flowering and pod development. Compared to the control, the early flower high temperature stress decreased (P , 0.01) pod production by 34% for Myles and 22% for Xena, whereas high temperature stress during pod development decreased (P , 0.05) seeds per plant by 33% for Myles and 39% for Xena. Consequently, the high temperature stress during pod development decreased (P , 0.01) seed yield by 59% for Myles and 53% for Xena. Yield reduction was greater due to the stress during pod development compared to the stress during early flowering. Plants recovered to a greater degree from the early flower stress compared to the pod development stress. The Myles desi produced 40 seeds per plant and the Xena kabuli produced 15 seeds per plant, whereas the Myles had smaller individual seed size than the Xena. Consequently, the Myles desi produced 26% greater seed yield than the Xena kabuli under the same conditions. Minimizing the exposure of chickpea to high temperature stress during pod development will increase pod fertility, seed set, and seed yield of the crop.

Typic Borolls) soil zones of the Canadian prairies (Gan and Noble, 2000). The area planted to lentil in Saskatch-Crops grown in previous years impact the amounts of residual soil ewan increased from 300 000 ha in 1995 to 670 000 ha water and nutrients available for subsequent plant growth. Appropriate sequences allow efficient use of the available soil resources by in (Anonymous, 2001. The inclusion of these crops the crop to increase yields at a system's level. This study was conducted as alternatives to cereals allows producers to become to determine whether the grain yield and grain crude protein concenless reliant on summer fallow and monoculture cropping tration (GCPC) of durum wheat (Triticum turgidum L.) were related systems. Expanded production of these alternative crops to crops grown in the previous 2 yr. Durum was grown following provides producers the opportunity to grow cereal crops pulses [chickpea (Cicer arietinum L.), lentil (Lens culinaris Medik.), on different types of stubble. The rotational benefits and dry pea (Pisum sativum L.)], oilseed [mustard (Brassica juncea derived from these opportunities are not well docu-L.) or canola (B. napus L.)], and spring wheat (Triticum aestivum L.) in southwest Saskatchewan from 1996 to 2000. Durum increased mented in this region. grain yields by 7% and GCPC by 11% when grown after pulse cropsTypes of crops grown in previous years may impact rather than after spring wheat. Durum after oilseeds increased grain the soils differently, affecting the amounts of residual yield by 5% and GCPC by 6%. Pulse and oilseed crops grown for soil water and nutrients available for subsequent plant the previous 2 yr increased durum grain yield 15% and GCPC 18% growth. Arranging crops in an appropriate sequence compared with continuous wheat systems. Fall residual soil NO 3 -N allows them to use the available resources more effiand available soil water accounted for 3 to 28% of the increased durum ciently and improves soil productivity at a system's level. yield in two of five site-years, whereas those two factors accounted for Zentner et al. (2001) reported that spring wheat GCPC 12 to 24% of the increased GCPC in three of five site-years. Durum grain yield was negatively related to GCPC. The relationship was

. 2003. Optimum plant population density for chickpea and dry pea in a semiarid environment. Can. J. Plant Sci. 83: 1-9. Chickpea (Cicer arietinum L.), an annual grain legume, is being broadly included in cereal-based cropping systems throughout the semiarid Canadian prairies, but information on optimum plant population density (PPD) has not been developed for this region. This study, which was conducted from 1998 to 2000 in southwestern Saskatchewan, determined the effect of PPD on field emergence, seed yield and quality, and harvestability of kabuli and desi chickpea compared with dry pea (Pisum sativum L.). Seed yields of all legumes increased with increasing PPD when the crops were grown on conventional summerfallow. The PPD that produced the highest seed yields ranged from 40 to 45 plants m -2 for kabuli chickpea, from 45 to 50 plants m -2 for desi chickpea, and from 75 to 80 plants m -2 for dry pea. When the legumes were grown on wheat stubble, the PPD that gained optimum seed yield ranged from 35 to 40 plants m -2 for kabuli chickpea, from 40 to 45 plants m -2 for desi chickpea, and from 65 to 70 plants m -2 for dry pea. The proportion of large-sized (>9-mm diameter) seed in the harvested seed was >70% when the kabuli chickpea was grown on summerfallow regardless of PPD, whereas the large-seed proportion decreased with increasing PPD when the crop was grown on wheat stubble. Increases in PPD advanced plant maturity by 1.5 to 3.0 d and increased the height of the lowest pods from the soil surface by 1.4 to 2.0 cm (or 5 to 10%), with desi chickpea receiving the greatest benefits from increased PPD. The percentage of plants established from viable seeds per unit area decreased substantially as PPD increased, with kabuli chickpea emergence decreasing from 90% at PPD = 20 plants m -2 to 72% at PPD = 50 plants m -2 , from 81 to 69% for desi type, and from 83 to 59% for dry pea. The reason for the low field emergence with increased PPD is unknown, but methods which lead to improved field emergence represent a great opportunity to increase seed yield and reduce production costs for both chickpea and dry pea in this semiarid region. Quand on cultive le pois chiche kabuli sur une jachère d'été, la proportion de grosses semences (> 9 mm de diamètre) dépasse 70 %, peu importe la DPO, mais un relèvement de cette dernière diminue la proportion de grosses semences quand la culture pousse sur du chaume de blé. Une hausse de la DPO permet aux plants de parvenir à maturité de 1,5 à 3,0 jours plus tôt et les gousses les plus basses dépassent le sol de 1,4 à 2,0 cm de plus (soit 5 à 10 %). C'est le pois chiche desi qui bénéficie le plus d'un relèvement de la DPO. La proportion de plants issus de semences viables par unité de surface diminue sensiblement avec l'augmentation de la DPO. Ainsi, le pourcentage de levée du pois chiche kabuli tombe de 90 à 72 % quand la DPO passe de 20 à 50 plants au m 2 , alors qu'il tombe de 81 à 69 % pour le pois chiche desi et de 83 à 59 % pour le pois de grande culture. On ignore pourquoi une ...

. 2002. Cropping sequence affects wheat productivity on the semiarid northern Great Plains. Can. J. Plant Sci. 82: 307-318. Extension of the commonly used spring wheat (Triticum aestivum L.)-fallow rotation to include broadleaf crops requires information on their effects on a following wheat crop. We grew a spring wheat test crop on the stubbles of wheat and seven broadleaf crops: desi chickpea (Cicer arietinum L.), dry bean (Phaseolus vulgaris L.), dry pea (Pisum sativum L.), lentil (Lens culinaris L.), mustard (Brassica juncea L.), safflower (Carthamus tinctorius L.), and sunflower (Helianthus annuus L.). This study was conducted near Swift Current, SK, from 1993 to 1997, and Congress, SK, from 1995 to 1997. After harvest, soil water differed among crop stubbles and by sampling depth. To the 60-cm depth, only soil under dry bean stubble held more water (8 mm), while soil under lentil, desi chickpea, sunflower and safflower stubbles held less water (6, 8, 9 and 17 mm, respectively) than wheat stubble (P < 0.05). From 60 to 120 cm, soil under dry pea and dry bean held more water (7 and 10 mm, respectively), and under sunflower and safflower stubbles less (7 and 14 mm, respectively), than under wheat stubble (P < 0.05). Lentil, dry bean and dry pea stubbles averaged 5, 6 and 9 kg ha -1 greater soil N in the 0-to 120-cm soil depth than wheat stubble (P < 0.05). The average yield of wheat grown on the four pulse crop stubbles was 21% greater than yields on wheat stubble, but did not differ from the oilseed stubbles (P < 0.01). Compared to wheat stubble, wheat grown on broadleaf crop stubbles had higher grain protein concentrations, increasing by 8 and 5%, for pulses and oilseeds, respectively (P < 0.01). Nitrogen removal in the wheat test crop grain yield averaged 15 kg ha -1 for pulse stubbles compared with wheat stubble. Soil N contribution by pulse stubbles was an important factor contributing to wheat growth under a dryland cropping system on the northern Great Plains. Après la récolte, la teneur en eau du sol variait avec les résidus de culture et la profondeur de l'échantillonnage. À 60 cm de profondeur, seul le sol sous chaume de haricot contenait plus d'eau (8 mm) que celui sous chaume de blé, tandis que le sol sous chaume de lentille, de pois chiche desi, de tournesol et de carthame en renfermait moins (6, 8, 9 et 17 mm, respectivement) (P < 0,05). Entre 60 et 120 cm de profondeur, le sol sous chaume de pois et de haricot contenait plus d'eau (7 et 10 mm, respectivement) que celui sous chaume de blé tandis que celui sous chaume de tournesol et de carthame en renfermait moins (7 et 14 mm respectivement) (P < 0,05). En moyenne, le chaume de lentille, de haricot et de pois apporte 5, 6 et 9 kg de N de plus par hectare au sol que le chaume de blé, à une profondeur de 0 à 120 cm (P < 0,05). Le blé cultivé sur le chaume des quatre légumineuses a donné un rendement moyen de 21 % supérieur à celui du blé cultivé sur le chaume de blé, mais son rendement était identique à celui du blé cultivé sur chaume d'oléagineu...