International Journal of Plant Production
Volume:5 Issue: 1, Jan 2011

Nitrogen fertilizer application rates in intensive agricultural systems have increased dramatically in recent years, especially in protected vegetable production systems. This excessive use of nitrogen fertilizer has resulted in soil secondary salinity, which has become a significant environmental stress for crops such as cucumber, in the protected farmlands. It is thus necessary to illuminate how crops respond to nitrate stress. The objective of this work was to investigate the influence of three nitrate levels of 14 (CK), 56 (T-1), and 140 (T-2) mmol L-1 on glutamine and asparagine content in the roots, stems, and leaves of cucumber (Cucumis sativus L. cv. Xintaimici) seedlings grown in hydroponic culture. The results showed that glutamine content in the roots, stems, and leaves of T-1 was a little higher than CK. In the roots, stems and leaves of T-2, glutamine content dramatically decreased over treatment course, and at 12 d decreased by 76%, 46% and 68%, respectively, with respect to CK. Asparagine content in the roots, stems, and leaves of T-1 was not significantly different from CK, whereas, in the roots, stems, and leaves of T-2 seedlings asparagine content decreased significantly. At 12 d, asparagine content in the roots, stems, and leaves of T-2 decreased by 78%, 60% and 74%, respectively, with respect to CK. This evidence indicates that the underlying mechanism of nitrate stress might be different from other abiotic ones such as salt stress and drought, which often stimulate the synthesis of amides.

To examine the genetic variation for drought stress in chamomile, eight accessions belonging to four species were evaluated under both field and greenhouse conditions using normal and late season drought stress. In the field experiment drought stress were initiated with irrigation cease at the commencement of flowering time. In greenhouse experiment, irrigation carried out at flower initiation when soil moisture reached to 80% and 50% of field capacity in control and drought stress treatments respectively. Orthogonal comparison showed high inter-and intra-species variation for all studied traits. In both experiments, drought stress caused significant reduction of flowering period, maturity time, flower number per plant, flower diameter, flower fresh and dry weight per plant, plant fresh and dry weight and plant relative water content. In field condition under both control and drought stress Gorgan1 accession (Anthemis alltissima) showed the highest flower fresh and dry weight. In greenhouse experiment, Isfahan (Matricaria chamomilla) and Mashhad (Tripleurospermum sevance) accessions produced greater flower yield and total dry mater under control and drought stress conditions, respectively. Minimum reduction due to drought stress for this two traits in the field experiment was for Ilam2 (Anthemis psedocotula) and in greenhouse experiment was for Ilam1 (Anthemis psedocotula) accessions. The maximum reduction rate due to drought stress in most genotypes was related to plant and flower fresh and dry weight. Tripleurospermum sevance species showed less reduction in fresh and dry flower weight when encountered to drought stress, hence it is more drought tolerant as compared to other investigated chamomile species.

Drought is a major constraint to crop production worldwide and landraces are one of the important genetic resources to crop improvement in the dry areas. The objective of this study was to investigate transpiration and yield responses of bambara groundnut (Vigna subterranea L. Verdc.) landraces exposed to a intermittent drought spell at an early reproductive stage. The four landraces (S19-3, Uniswa Red, LunT, and Ramayana collected from Namibia, Swaziland, Sierre Leone, and Indonesia, respectively) were grown in pots in a climate-controlled greenhouse and were either wellwatered (WW) daily to 90% of pot holding capacity until seed maturity or drought-stressed (DS) in the period from 76 to 85 days after sowing (flowering and early podding stage). During drought, although the total water use differed among the four landraces, transpiration rate and stomatal conductance (gs) responded similarly to soil drying. The high soil water thresholds for the reduction of transpiration rate and gs of bambara groundnuts indicate their great sensitivity in the stomatal control over plant water loss during soil drying. Even though the shoot dry weight at maturity was hardly affected by DS, seed yield, seed number, and harvest index were all significantly decreased in the DS plants. Among landraces, LunT and Ramayana were more susceptible to DS than S19-3 and Uniswa Red in terms of reduction of seed number and seed yield. The different responses of the landraces to DS may reflect their adaptation to their local climate at the site of collection being that landraces collected from wet regions were more vulnerable to DS than those collected from dry areas.

Due to increasing water and growing demand for food a more efficient water use system is needed for agriculture. This is more evidence for rice production with a higher water use for economical production. A large cultivar×water regime interaction exists for grain yield in rice. Therefore, information is required to adopt new rice cultivars with high yield potential under watersaving conditions. The objectives of this study were to analyze the straw yield, grain yield, yield components, water use and water productivity of six rice cultivars (Anbarboo-22, Ghasroddashti, Cross-Domsiah, Hasani, Rahmat-Abadi, and Doroodzan) under water-saving irrigation regimes (intermittent flood irrigation with 1-and 2-day intervals, I-1-D, and I-2-D, respectively) compared with continuous flood irrigation (CFI) to adopt the elite cultivars of semi-arid area for water-saving conditions. Results indicated that under water-saving irrigation regimes (I-1-D), Doroodzan, Anbarboo-22, and Cross-Domsiah cultivars produced higher grain yields and are elite cultivars, however, under I-2-D irrigation regime only Anbarboo-22 cultivar was an elite cultivar. Based on the harvest index criterion, Doroodzan and Anbarboo-22 cultivars are the elite cultivars under watersaving irrigation regimes. The grain yield of the cultivars was mostly controlled by 1000-grain weight and the order of the other yield components were number of grains per panicle > number of panicles per unit area > unfilled grain percentages. Under CFI, Doroodzan cultivar resulted in highest water productivity (WP) as 0.52 kg m-3 and Cross-Domsiah and Anbarboo-22 cultivars with WP of 0.40 and 0.31 kg m-3 were in second and third place, respectively. Furthermore, based on the drought tolerance indices, it is concluded that Doroodzan at first place and Anbarboo-22 and Cross-Domsiah cultivars at second place may be considered as drought tolerant cultivars that can be used in further field study with water-saving irrigation regimes i.e., intermittent irrigation with 1-and 2-day intervals in Fars province.

High quality water is less available for agriculture and thus farmers often use saline water, that affects crop growth and yield. Snap bean (Phaseolus vulgaris) is sensitive to soil and water salinity, and also to heat stress. The aim of this research is to evaluate if a postponed transplant (high temperature stress) of snap bean can influence growth and yield under saline conditions. Snap bean ‘Bolero’ was irrigated with water at 5 salt levels (0.7, 3.0, 6.0, 9.0 and 12.0 dS m-1) in factorial combination with two transplant time: ordinary (first week of June=OT) and postponed (first week of July=PT). The percentage of plant survival and plant growth were measured throughout the whole growth cycles. Irrigations with saline water resulted in increased values of soil salinity. The PT cycle was shorter than OT cycle and fewer accumulated GDDs were necessary for ripening (658.7 °C vs. 790.5 of OT cycle). Saline treatments caused a decrease of survival percentage, growth, LA and yield. Also high temperature stress determined a decrease of growth and yield, especially of number of marketable pods per square meter, not compensated by a higher plant density. Therefore, it doesn’t seem favourable to postpone the transplant of snap bean under saline conditions.

Reduced seedling growth is a consequence of seed deterioration. The heterotrophic seedling growth can be considered as the product of three components: (1) initial seed weight, (2) the fraction of seed reserves which are mobilized, and (3) the conversion efficiency of mobilized seed reserves to seedling tissues. It is not clear which of these component (s) is affected by seed deterioration. To study this subject, germination characteristics and seedling growth from deteriorated soybean (Glycine max) seeds were studied; seeds were incubated at two different temperatures of 34 ºC and 40 ºC for varying times. The results indicated that seed deterioration results in decreased percentage and rate of germination and decreased percentage of normal seedlings. Seedling growth and the fraction of seed reserve mobilization indicated a significant decrease with the advance of deterioration. However, the effect of seed deterioration on the conversion efficiency of mobilized reserves to seedling tissues was not significant. Thus efforts to improve seedling germination and growth in plant breeding programs should focus on improvement of fraction of mobilized seed reserves.

It has long been recognized that bread making quality traits vary considerably as a result of genotype, environment and their interaction. The present study was aimed at determining the effect of cultivar, environment and their interaction on several bread making quality traits as well as to analyze relationship between these traits, Hundred forty wheat genotypes originated from 28 countries were grown in 2000, 2001, 2002 and 2003. Data of 9 bread making quality traits, protein content (PC), wet gluten content (WG), farinograph absorption (FA), farinograph dough development time (FD), farinograph quality number (FQU), resistance to extension (ER), falling number (FN), loaf volume (LV), and baking score (BS), were used to evaluate the effects of cultivar, environment and their interaction. The analysis of variance, ANOVA, and estimates of the components of variance due to genotype and genotype/environment interaction were calculated according to Comstock and Moll (1963). Heritability estimates were similar to those reported by Singh et al. (1993), Both cultivar and cultivar by environment interaction had significant effects on all quality traits. Variances of quality traits associated with genetic factors (cultivar) were generally larger than those for cultivar by environmental interaction effects, The dominant effect of the cultivar in total variance is probably due to the wide range of bread making quality traits in the examined cultivar set.

Agriculture of the inland arid region in Xinjiang depends on irrigation, which forms oasis of Northwest China. The production and water use of wheat, a dominant crop there, is significantly affected by undergoing climate variability and change. The objective of this study is to quantify interannual variability of wheat yield and water use from 1955 to 2006. The farming systems model APSIM (Agricultural Production Systems Simulator) was used to evaluate crop yield, evapotranspiration (ET), and water use efficiency of winter and spring wheat (Triticum aestivum L.) in Xinjiang from 1955 to 2006. The APSIM model was first calibrated and validated using 6 years of experimental data. The validated model was then applied to simulated wheat yield and ET using climatic and soil data for present crop cultivar. Simulated wheat yield under full irrigation have no significant decreasing trend from 1955 to 2006. Simulated growth duration of winter wheat was significantly decreased. Simulated ET of winter wheat was significantly correlated with measured pan evaporation. Simulated ET of winter wheat decreased significantly during the 52 years, with a decrease rate of 0.813 mm year-1. Cluster analysis showed that the variations of ET were mainly determined by solar radiation, nothing to do with the changes in temperature. The results identified the change trend of field ET under historical climate change, and determined the main meteorological factors which affect ET in this oasis. These results provide a measure for water demand, crop production and irrigation management under climate change in the oasis.

Combining effects of soil solarization and grafting on soilborne pathogens, plant height and yield in cucumber were compared in a greenhouse of Bati Akdeniz Agricultural Research Institute located in Antalya in 2008 fall season. The experiment was set in split plot design containing; 1, 2, 4 and 5 months soil solarization (MSS), and non-solarized control plots (NSC) on which grafted Maximus F1+ Bergama F1 and non-grafted Bergama F1 were grown. Almost all of plants grown in nonsolarized plots were infected with root-knot nematodes with severe root damages; however, only a few plants were affected by this nematode in 4 and 5 months solarized plots with very slight root galls. No resistance to root-knot nematodes was observed in both grafted and non-grafted plants. Almost half of the plants grown on non-solarized control plots were infected with Fusarium oxysporum f. sp. cucumerinum with relatively slight disease symptoms. In conclusion, combining solarization with grafting significantly promoted early flowering time, plant vigor, early and total yields and reduced nematode and fusarium wilt damages in this study.