International Journal of Plant Production
Volume:3 Issue: 1, Jan 2009

Abstract Saffron is grown in arid and semi-arid regions in Iran in late autumn, winter and late spring with rainy season. It should be irrigated by supplemental basin irrigation. Since rainfall is usually delayed in autumn, therefore, a pre-flowering irrigation of about 100 mm is needed. In areas with a seasonal rainfall of 600 mm a post- flowering irrigation of about 50 mm is adequate for economical yield. In areas with seasonal rainfall of 400 and 200 mm continuous supplemental irrigation is needed with intervals of 24 and 15 days or irrigation regimes of 50% ETp and 75% ETp, respectively. In these areas, irrigation regimes can be planned based on crop water stress index (CWSI) of 0.60 and 0.27, respectively. Monthly values of crop coefficient (Kc) and pan coefficient (Kp) for saffron are presented with the highest values of 1.10 and 0.84, respectively, that occurred in January. For the three-, four-and five-year old fields with higher amount of corm intensity the optimum irrigation water is zero for about 300 mm of rainfall. While for the six-and seven-year old fields the optimum irrigation water is zero for about 500 mm of rainfall. Flower production decreased 49% by using irrigation water with salinity level of 1.7 dS m-1 and no flower produced at salinity level of 4.0 dS m-1, while leaf growth occurred in this salinity. Furthermore, 50% flower yield is produced at soil water salinity of 3.6 dS m-1.

Drought stress is one of the most important abiotic stresses influencing performance of crop plants. Therefore, the identification or development of tolerant genotypes is of high importance for incorporating in cotton production. In this study to evaluate the effect of drought stress on some cotton traits, 5 improved cotton varieties were studied in a split plot design with three replications in 2 years (2000-2001) at 2 locations (Hashemabad and Anbaroloom); one with Mediterranean climate and the other with drought-stress condition. Treatments were irrigation as main plot in 3 levels (I0=without irrigation, I1=one time irrigation; that carried out 70 days after sowing, and I2=at least 3 times irrigation) and varieties as subplot in 5 levels (5 genotypes). In the basis of combined variance analysis significant differences were detected among varieties for yield, boll number, boll weight, length and number of sympodial and monopodial branches. Drought stress decreased yield, boll number, boll weight, and induced earliness. With increasing irrigation frequency, earliness lightly reduced in the former climate probably because of inducing vegetative growth and retarding in generative phase. In latter climate increased irrigation frequency had a positive effect on the yield. It seems that water deficiency has reduced yield via decreasing boll number. The number of formed bolls in stressful conditions was less than that of in non-stressful conditions. Stress tolerance index (STI) revealed that Siokra-324 and Tabladila were more tolerant and stable varieties.

The efforts were made to study the impact of vermicomposted and composted farmyard manure (FYM) along with some combination of NPK fertilizers, on field crop of garlic (Allium stivum L.). A total of six experimental plots were prepared: T1 (recommended doze of NPK), T2 (vermicompost @ 15t/ha), T3 (20 t/ha vermicompost), T4 (15t/ha vermicompost 50 % NPK), T5 (15t/ha farmyard manure), and T6 (farmyard manure 15t/ha 100% recommended NPK) to test the plant production patterns, under field conditions. The maximum range of some plant parameters i.e. root length, shoot length, leaf length, fruit weight, number of cloves in garlic fruit and number of leaves per plant was in the T4 treatment plot. Also, the average fruit weight was approximately 26.4% greater in T4 than recommended NPK treatment plot (T1). The vermicomposted FYM showed a comparatively better result of plant production than composted manure. The plant growth results indicate the presence of some growth-promoting substances in worm-processed material (vermicompost). The vermicomposted FYM also contained a considerable amount of some essential plant micronutrients e.g. Cu (0.973 mg kg-1), Fe (8.68 mg kg-1), Mn (13.64 mg kg-1) and Zn (16.91 g kg-1) that might be responsible for better plant growth and productivity. This study suggests that vermicomposted manures may be a potential source of plant nutrients for sustainable crop production.

The impact of different concentration of zinc (Zn) and boron (B) on growth and mineral composition of lemon seedlings (Citrus Aurantifolia L.) was studied under greenhouse conditions. We used five concentration levels of B (0, 2.5, 5, 10 and 20 μg g-1 soil) and three of Zn (0, 5 and 10 μg g-1 soil). Fresh and dry plant weights of the control treatment were strongly decreased with B levels higher than 5 μg g-1 of soil. In above mentioned B levels, lemon seedlings displayed slight to severe B toxicity symptoms. Zn treatments reduced B accumulation and the associated inhibitory effect on plant growth. Increased B level in soils enhanced the concentration of B in plant shoots to a greater extent in the absence of applied Zn. The effectiveness of Zn for the reduction of B accumulation and toxicity decreased as the level of applied B was increased. In a comparison of Zndeficient and Zn-treated soils, plant root and shoot analysis for B indicated an increased transport of B in the absence of Zn. The best plant production was achieved when 2.5 and 10 μg g-1 soil of B and Zn were applied simultaneously. This combination was associated with the highest uptake of Zn, nitrogen (N), phosphorous (P), potassium (K), iron (Fe), manganese (Mn) and copper (Cu), suggesting that the combination resulted to a suitable condition in which plants had a well-balanced nutritional status. While B application increased nutrients accumulation in plant shoot, the role of Zn was a dilution effect or antagonistic relationship. The results of this study indicated that supplemental Zn has potential and practical importance in the control of B absorption and toxicity in soil where plants are grown under Zn deficiency and B toxicity.

An experiment was carried out to assess the effect of four nitrogen levels viz. T1 (full doze of urea i.e. 215 kg urea ha-1 at 15 DAT), T2 (full doze of urea at two equal splits, ½ at 15 DAT ½ at 30 DAT), T3 (full doze of urea at two equal splits, ½ at 15 DAT ½ at 55 DAT) and T4 (full doze of urea at three equal splits, 1/3 at 15 DAT 1/3 at 30 DAT 1/3 at 55 DAT) on morpho-physiological attributes of Boro rice genotypes viz. V1 (BINAdhan 5), V2 (Tainan 3) and V3 (BINAdhan 6). Plant height, number of tillers hill-1, number of leaves hill-1, leaf area hill-1 (cm2), DM (dry matter) of root, stem and leaves hill-1, TDM (total dry matter) hill-1 and chlorophyll content in leaves (at 74 DAT), were increased with the split application of N. Among the treatments, T4 showed the best performance and grain yield (45.25 g hill-1) compared to control (30.61 g hill-1). Among the genotypes, BINAdhan 5 and BINAdhan 6 showed similar performance in respect of most of the parameters but BINA dhan 6 produced the highest grain yield (40.26 g hill-1) compared to BINA dhan 5 (35.54 g hill-1) and Tainan 3 (33.90 g hill-1). Full dose of urea (215 kg urea ha-1) applied at three equal split at 15, 30 and 55 DAT was found to be the most beneficial one for the all the rice genotypes. Leaf chlorophyll content had a strong contribution to grain yield of rice.

Phenolic extracts of canola (Brassica napuse L.) contains substances that inhibited the germination and seedling growth of soybean (Glycin max L.). These compounds also affect activity of some enzymes. Hear, we investigated the allelopathic effects of various canola plant parts on soybean germination, seedling growth, and biochemical aspects. Phenolic extract of canola shoot (including leaf, stem, and flower) and root were made by methanol 70%, to determine their effects on germination, seedling growth, and fresh and dry weight of hypocotyl and radicle of 8-d old soybean seedlings, and their effects on activity of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), polyphenoloxidase (PPO), protein content of hypocotyl and radicle, and lipid peroxidation (MDA) of radicle. The results showed that there were no significant differences in CAT activity and protein content. Increasing the phenolic extract concentration of separated canola plant parts decreased soybean germination and seedling length and weight, radicle was more sensitive to extract source than hypocotyl. The POD and SOD activity of radicle and hypocotyl and lipid peroxidation of radicle were increased by concentration of both phenolic extracts compared with control. The PPO activity of radicle and hypocotyl was increased under root extracts, but shoot extracts had not significantly effects. The degree of toxicity of canola root part was more than shoot part.

Amaranthus cruentus, an annual vegetable crop, is known to be highly productive under rain-fed conditions and during the dry season when supplied with water. However, for good water management, there is need to accurately quantify the water consumed by the crop. This paper investigates the water use and biomass yield of differentially irrigated Amaranthus cruentus at different developmental stages: emergence/vegetative, fruiting and maturity. Field experiments were conducted between January and March of 2005 and 2006. The experiment was a 2×3×3 combination of two irrigation methods (drip and sprinkler systems) three crop phenological stages (Emergence/vegetative, fruiting and maturity), and three water stress levels. A randomized complete block design (RCBD) was adopted. Soil moisture storages within the root zone depth (10-30 cm) of Amaranthus were highest (13.86 and 13.23 cm) on drip plots at the 71 day of year (DOY) during the 2005 and 2006 experiment respectively. This has direct influence on the evapotranspiration of the crop. The highest evapotranspiration were 12.87 and 9.96 mm day-1 during 2005 and 2006 respectively on plots irrigated under drip system. The highest and the lowest crop yield were 13.94 and 4.2 tonha-1, respectively in plots irrigated under drip irrigation system, and 11.16 and 3.39 tonha- 1, respectively in plots irrigated under sprinkler system. The non-linear model used for yield prediction showed good agreement with the field data with r2 = 0.94 and 0.74 for A. cruentus grown under drip and sprinkler irrigation systems, respectively. The correlation coefficient (r) between relative yield and relative evapotranspiration were 0.78 and 0.74 for crop under drip and sprinkler irrigation systems, respectively.

Boron (B) is essential to growth at low concentrations and limits growth and yield when in excess. Little is known regarding plant response to excess B and salinity occurring simultaneously. In this study, two models of Leibig-Sprengel (LS) and Mitscherlich-Baule (MB), originally proposed to explain plant response to nutrients only, were modified to evaluate canola yield response to combined levels of B and salinity stresses. The water salinity treatments were consisted of non-saline water, 3, 6, 9 and 12 dS m-1. The B treatments were 0, 10, 20 and 30 mg kg-1 added to soil as H3BO3. It was revealed that modified LS model can satisfactorily predict canola dry matter yield. The calculated statistics: Maximum Error, Root Mean Square Error, Modeling Efficiency, Coefficient of Determination and Coefficient of Residual Mass, indicated that the estimated relative dry matter yield for soil B concentrations and salinity levels by modified LS model compared to modified MB model was closer to the measured relative yield. Therefore, the use of modified LS model for estimating canola relative yield in salinity and B stresses is recommended. The threshold value of salinity increased with higher B concentration and maximum dry matter yields decreased with increasing B concentration. Excess B was found to decrease dry matter yield of canola. This effect was inhibited when plants were exposed to simultaneous B and salinity stresses. Both irrigation water salinity and B concentration influenced water use efficiency (WUE) of plant, however, only B concenteration influenced canola yield in in the same manner.

In this study, quantitative trait loci (QTLs) controlling rice heading date were detected in a F2:3 population derived from a cross between an indica rice variety, Tarom Mahalli, with early heading date, and an indica variety, Khazar, with late heading date. SSR linkage map was constructed using 74 polymorphic markers and 192 F2 individuals and covered a total of 1231.50 cM of rice genome. QTL mapping of heading date was performed by simple and composite interval mapping. Three major genes (hd1, hd4 and hd9) were identified on chromosomes 1, 4 and 9 and two minor genes (hd2a and hd2b) were mapped on chromosome 2. Major genes explained over 60% of total phenotypic variation and had negative additive effects for decreasing heading date. These results will be useful in marker-assisted breeding to improve rice genotype with early heading date.

A partial diallel design was used among 20 maize inbred lines to form 110 F1 hybrids to generate information on the values of these lines for developing insect resistant maize varieties during the short rains season of 2006. The hybrids were evaluated for resistance to the C. partellus and B. fusca, and for agronomic performance over two seasons during long and short rains of 2007 at a mid-altitude dry early maturity site at KARI Kiboko, and the moist mid-altitude medium maturity site at KARI Embu. leaf damage score (using a scale of 1-9 where: 1= No damage and 9= extremely damaged), number of exit holes, cumulative tunnel length, and grain yield were measured as resistance traits. The genotype sum of square was partitioned into general combining ability (GCA) and specific combining ability (SCA) effects. Maize inbred lines with good general combining ability for insect resistance including maize inbred lines with significant and negative GCA`s for leaf damage were identified as lines 12,16,18,19 and 20 at Kiboko and lines 8, 17, 18, and 20 in Embu. Results showed that the problem of stem borers intensified by over 40% within four years in the experimental region of Eastern Kenya; currently mean yield loss due to stem borers was assessed to be about 56%. Several hybrids had significant negative SCA for leaf damage and significant positive SCA for grain yield. The maize inbred lines studied revealed their potential for use in breeding programs for insect resistance that could result in a correlated response for increased grain yield. Recurrent selection would be the best option to develop high yielding insect resistant germplasm for this region of Kenya considering that additive gene action were predominant. Evidently, it would be more difficult to develop host plant resistance to B. fusca than to C. partellus.