Late Sowing Dates Research Articles

Modeling the Impact of Climate Change on Production of Sesame in Western Zone of Tigray, Northern Ethiopia

Sesame is one of the most important cash crops which is mostly grown in the western and north western zone of Tigray region. The impact of climate change on sesame yield were not addressed yet particularly in the study area. Therefore, this study was aimed at assessing the impact of climate change on production of Sesame in the Western lowlands of Tigray, with the specific objective of modeling the impact of climate change on production of sesame. Historical sesame yield was obtained and climate outputs from HadGEM2-ES, ACCESS1-0 and GFDL-ESM2M models were projected for the near (2010-2039), mid (2040-2069) and end (2070-2099) term periods to evaluate future impacts of climate change. In all periods (near, mid and end term) normal sowing date was better than early and late sowing dates in terms of yield. In late sowing date, yield was simulated to reduce from -5.88% to -23.31% in the end term RCP8.5 by GFDL-ESM2M and HadGEM2-EM climate models respectively. However, in the normal sowing date the yield was increased up to 33.1% by GFDL-ESM2M model in the midterm RCP4.5. Generally, higher yields were found in the normal sowing date. The response of sesame cultivars to the future climate changes should be studied under different management options. The impact should also be studied by different crop and climate models so as to capture the possible variability of sesame yield. Sensitivity to carbon dioxide, temperature, rainfall and other different management activities should be undertaken.

Effects of Meteorological Parameters Created by Different Sowing Dates on Drip Irrigated Cotton Yield and Yield Components in Arid Regions in China

Meteorological parameters significantly affect cotton growth and development, and selecting an optimum sowing date can improve seed cotton yield. The experiment consisted of sowing a film-covered, drip-irrigated cotton field (Gossypium hirsutum L.) on four sowing dates from April to May and took place in 2011 and 2012 at the Agrometeorological Experimental Station of Wulanwusu, which was in an arid region of north-western China. The results showed that late sowing dates produced less aboveground dry biomass, yield and water-use efficiency (WUE) than did the normal sowing dates. The yield increased with the increases of mean diurnal temperature range (DTR) from full bloom to maturity, mean temperature and sunshine hours (SH) during the whole growing season, accumulated temperature (AT) and days from squaring to anthesis, and mean temperature during the reproductive stage. The yield decreased with the increases of AT and days from sowing to emergence. However, the main effect factors of meteorological parameters were AT from squaring to anthesis, mean temperature during the whole growing season and AT from sowing to emergence. It was significant to choose the optimal planting date to improve yield. Meanwhile, yield was also affected by leaf area index (LAI), boll number per plant and gin turnout. However, the main effect factors of yield component were boll number per plant, gin turnout and boll weight. Boll number per plant suffered from mean DTR from boll setting to maturity and SH during the whole growing season. Gin turnout was affected by mean temperature during the whole growing season and mean DTR from boll setting to maturity. The relationship between yield and boll weight was insignificant. Sowing date, year and interaction (sowing date × year) all significantly affected the yield. Thus, sowing date was an important factor affecting the yield, biomass and reproductive duration and minimized the impact of temperature and duration of the reproductive growth stage. With climate change, an earlier planting date might be an efficient method of increasing yield in the future.

단옥수수 주요 품종의 등숙 중 종실 이화학적 특성 변화

본 연구에서는 단옥수수 주요 품종인 고당옥과 구슬옥을 재배하여 고품질 단옥수수 생산 재배법을 보급하기 위한 기초자료를 제공하고자 종실의 등숙 중 이화학적 특성 변화를 조사하였다. 파종시기와 관계없이 등숙이 진행됨에 따라 수분 함량은 감소하고, 종실 100립의 생중과 건중은 증가하였고(p<0.05), 파종시기가 늦어질수록 100립중의 증가 속도는 느려졌다. 종실의 조단백과 조회분 함량은 출사 후 일수가 경과함에 따라 감소하는 경향을 보였고, 조지방 함량은 유의하게 증가하였다(p<0.05). 단옥수수 종실의 총 유리당 함량은 파종시기와 관계없이 출사 후 일수가 경과함에 따라 유의하게 감소하였으나(p<0.05), 유리당을 구성하는 fructose, glucose, sucrose와 maltose의 조성은 파종시기에 따라 차이를 보였으며 그 중 sucrose가 대부분을 차지하고 있었다. 종실의 전분 함량과 경도는 출사 후 일수가 경과함에 따라 유의하게 증가하는 경향을 보였으며(p<0.05), 전분 함량의 증가 속도 역시 100립중과 마찬가지로 파종이 늦어질수록 느려지는 경향을 보였다. 수확 적기의 종실 수분함량은 68~69% 정도였으며, 전분 함량은 7월 10일 파종이 가장 높았고 7월 30일 파종이 가장 낮았다. 적기에 수확한 단옥수수의 단맛을 비교한 결과 고당옥은 4월 10일 파종한 것에 비해 7월 20일, 7월 30일 파종이 약 1.8배와 1.4배 단맛이 높은 반면 구슬옥은 파종시기와 상관없이 단맛의 정도가 비슷하였다. This study was conducted to investigate the kernel characteristics of sweet corn during ripening with different sowing date. Godangok and Guseulok were sown at April 10, July 10, July 20, and July 30 in 2013. Irrespective of sowing date, fresh and dry weight of 100 kernel, starch content, crude fat content, and hardness of sweet corn kernels were significantly increased according to maturation (p<0.05). But moisture content, total sugar content, crude protein content and crude ash content of sweet corn kernels were significantly decreased according to maturation (p<0.05). The changing rates of 100 kernel weight and starch content on kernels were faster at early sowing date than at late sowing date. The moisture content of sweet corn kernels was 68~69% at optimum for harvesting. The degree of sweetness on Godangok was about 1.8 and 1.4 times higher in sowing at July 20 and July 30 than in sowing at April 10. On the other hand, the degree of sweetness was similar regardless of sowing time on Guseulok. These results will be helpful to farmers for fall-harvest sweet corn cultivation and management.

Determining optimum sowing date of wheat using CSM-CERES-Wheat model

Wheat production in the south of Khuzestan, Iran is constrained by heat stress for late sowing dates. For optimization of yield, sowing at the appropriate time to fit the cultivar maturity length and growing season is critical. Crop models could be used to determine optimum sowing window for a locality. The objectives of this study were to evaluate the Cropping System Model (CSM)-CERES-Wheat for its ability to simulate growth, development, grain yield of wheat in the tropical regions of Iran, and to study the impact of different sowing dates on wheat performance. The genetic coefficients of cultivar Chamran were calibrated for the CSM-CERES-Wheat model and crop model performance was evaluated with experimental data. Wheat cultivar Chamran was sown on different dates, ranging from 5 November to 9 January during 5years of field experiments that were conducted in the Khuzestan province, Iran, under full and deficit irrigation conditions. The model was run for 8 sowing dates starting on 25 October and repeated every 10days until 5 January using long-term historical weather data from the Ahvaz, Behbehan, Dezful and Izeh locations. The seasonal analysis program of DSSAT was used to determine the optimum sowing window for different locations as well. Evaluation with the experimental data showed that performance of the model was reasonable as indicated by fairly accurate simulation of crop phenology, biomass accumulation and grain yield against measured data. The normalized RMSE were 3%, 2%, 11.8%, and 3.4% for anthesis date, maturity date, grain yield and biomass, respectively. Optimum sowing window was different among locations. It was opened and closed on 5 November and 5 December for Ahvaz; 5 November and 15 December for Behbehan and Dezful;and 1 November and 15 December for Izeh, respectively. CERES-Wheat model could be used as a tool to evaluate the effect of sowing date on wheat performance in Khuzestan conditions. Further model evaluations might also be needed for other cultivars which are released for this region.

파종시기에 따른 유채(Brassica napus L.) 품종별 생육 및 개화특성

유채는 겨울철 유휴지와 하천부지 등의 효율적인 이용과 환경보호 측면에서 이모작이 가능하다는 장점이 있고, 보리수매제도 폐지로 인한 농가 소득 보전을 위한 대체 가능성이 크다. 이에 국산장려 품종인 선망, 탐미유채, 탐라유채, 내한유채, 한라유채, 영산유채를 이용 파종시기를 달리하여 각 품종의 수량과 개화지속기간을 구명하여 바이오에너지 원료확보 및 경관용으로서의 효율을 극대화하고자 본 실험을 수행하였다. 유채 품종별 파종시기 및 주요 수량구성요소, 종실수량의 분산분석 결과 파종시기와 품종의 효과는 천립중을 제외한 모든 조사형질에서 고도의 유의성이 인정되었고, 파종시기와 품종의 상호작용은 입모주수, 경장, 종실중과 고도의 유의성을 보였으며 협수와 천립중과는 p < 0.05 수준의 유의성이 인정되었다. 수량구성 요소인 경장과 협수, 결실립수 등은 수량을 증가시키는 요인이기 때문에 <TEX>$m^2$</TEX>당 입모수가 많고 이들 수량구성요소의 발현이 높게 하는 것이 효과적이다. 본 실험의 종실중은 역시 어느 품종을 막론하고 파종기가 늦어지면 늦어질수록 거의 직선적으로 감소하는 경향을 나타내었다. 이와 같은 이유는 파종기가 빠를수록 협수가 많아져 source의 경합이 컸었음에 기인하는 것으로 종실중은 천립중 보다는 결실립수를 결정하는 주당 협수에 의하여 가장 크게 좌우된다고 생각된다. Schukking (1984)은 유채는 재식밀도가 좁아짐에 따라 유채의 개화기까지의 일수가 늦어지고, 총 분지수, 엽수 등의 형질은 왜소해진다고 하여 파종기 변화에 따른 재식밀도에 대한 추가적인 구명도 해야 할 것이다. 한편으로 적절한 파종시기의 선택은 입모수가 많은 밀식상태이고 영양생장기간이 길어지므로 자연적으로 수량구성요소의 생육상황이 좋아지는 것으로 생각된다. 이러한 결과를 보면 무안지역에 있어서 유채 종자 채종을 위한 파종 적기는 10월 5일 이전으로 판단되는데 파종기가 늦어질 경우 영양생장기간이 짧아지기 때문에 생육일수의 단축에 의하여 유묘의 건조, 하고 현상 등의 문제점이 발생되어 수량구성요소가 감소되기 때문에 재식밀도의 변화를 준다면 수량감소 요인을 줄일 수 있을 것이라 생각된다. 한편 유채품종 별 개화지속일수는 9월 25일 파종의 경우 선망 > 탐미유채 > 영산유채 > 내한유채 > 한라유채 > 탐라유채 순 이였고, 파종일이 빠를수록 품종 간 개화기 차이가 뚜렷함을 확인하였으며 파종일이 늦을 경우 품종 간 개화기 차이는 거의 없었다. 경관효율을 극대화하기 위해서는 선망, 탐미, 영산 유채 등을 9월 25일 조기파종하고 탐라, 내한유채를 파종기를 달리하여 파종하였을 경우 최대 4월 3일부터 5월 14일까지 유채꽃을 관상할 수 있었다. 전체적으로 파종일 차이에 따라 각 품종별로 약 1~14일 정도 개화지속일수차이를 보였으며, 개화종기에 비해 약 2~9일 정도 개화기를 연장 할 수 있었다. 본 실험의 결과 중생종과 만생종인 한라, 내한, 탐라유채에 보다는 조생종의 특성을 보이는 선망, 탐미, 영산유채 품종을 축제기간에 맞춰 파종시기를 조절한다면 축제기간에 꽃이 피지 않아 발생하는 고민을 일정부분 해결할 수 있을 것이라 판단된다. This study was carried out to understand the effect of sowing date on growth characteristics, flower duration of a total of 6 domestic rapeseed cultivars, "Sunmang", "Tammiyuchae", "Tamlayuchae", "Naehanyuchae", "Yongsanyuchae" and "Hallayuchae" with different sowing dates (25 Sept., 5 Oct., 15 Oct., 25 Oct., 5 Nov.) in Muan, Jeollanamdo, Republic of Korea. The results obtained were summarized as the follows: The number of seedling stand after overwintering was decreased in all 6 cultivars. It changed little until 5 Oct., and then showed continuously largely decrease as the sowing date being delayed. As the sowing date was being delayed, plant height was decreased while Silique length and thousand seed weight were increased. Seed yield in all 6 cultivars decreased almost linearly with late sowing date. In correlation analysis between the delaying sowing date and growth characteristics, it was inversely correlated with plant height (<TEX>$r=-0.769^{**}$</TEX>), No. of branches/plant (<TEX>$r=-0.760^{**}$</TEX>), No. of siliqua/panicle (<TEX>$r=-0.631^{**}$</TEX>) and seed yield (<TEX>$r=-0.946^{**}$</TEX>), while showed a positive correlation with silique length (r=0.635), seed diameter (<TEX>$r=0.629^{**}$</TEX>) and thousand grain weight (<TEX>$r=0.422^*$</TEX>). No. of seeds/silique and seed set percentage were not significantly correlated with the delaying sowing date. The flower duration was long in order of Sunmang, Tammiyuchae, Yongsanyuchae, Naehanyuchae, Hallayuchae and Tamlayuchae. Varietal variation of flowering date was larger with early sowing date than with delaying sowing date. The range of flower duration across all cultivars was from 1 day of Tamlayuchae to 14 days of Sunmang according to the sowing date, and the end flowering date was able to be extended from 2 to 9 days, compared to normal date of end flowering.

Identifying the critical period for waterlogging on yield and its components in wheat and barley

Crop tolerance to waterlogging depends on factors such as species sensitivity and the stage of development that waterlogging occurs. The aim of this study was to identify the critical period for waterlogging on grain yield and its components, when applied during different stages of crop development in wheat and barley. Two experiments were carried out (E1: early sowing date, under greenhouse; E2: late sowing date, under natural conditions). Waterlogging was imposed during 15–20 days in 5 consecutive periods during the crop cycle (from Leaf 1 emergence to maturity). The greatest yield penalties occurred when waterlogging was applied from Leaf 7 appearance on the main stem to anthesis (from 34 to 92 % of losses in wheat, and from 40 to 79 % in barley for E1 and E2 respectively). Waterlogging during grain filling reduced yield to a lesser degree. In wheat, reductions in grain number were mostly explained by reduced grain number per spike while in barley, by variations in the number of spikes per plant. The time around anthesis was identified as the most susceptible period to waterlogging in wheat and barley. Exposing the crop to more stressful conditions, e.g. delaying sowing date, magnified the negative responses to waterlogging, although the most sensitive stage (around anthesis) remained unchanged.

Effect of Date of Sowing on the Performance of Drought Tolerant Wheat Genotypes to Spot Blotch at Rampur, Chitwan , Nepal

A research was conducted in field to elucidate the response of 20 twenty drought tolerant wheat genotypes to spot blotch. Field experiment was carried out in Agronomy block of IAAS, Rampur, Chitwan in split plot design with three replications, considering 25 November as normal sowing and 15 December as late sowing dates taking them as main factors and genotypes as sub factors. Grain yield was 2.50 t ha-1 on 25 November sowing and 2.03 t ha-1 on 15 December sowing. Similarly thousand kernel weight was 37.50 g on 25 November sowing and 32.82 g on 15 December sowing. Aditya, CSISA DRYT 5204 and CSISA DRYT 5205 had less than 13% grain yield and TKW reduction when sown in late condition also. From the experiment it is concluded that these three genotypes can be sown in late condition as they were resistant to spot blotch and heat stress.DOI: http://dx.doi.org/10.3126/ijasbt.v1i4.9180 Int J Appl Sci Biotechnol, Vol. 1(4): 266-271

Energy crop production in double-cropping systems: Results from an experiment at seven sites

Energy crop production for fermentation in biogas plants significantly increased in the last years. At present maize is the most common energy crop for biogas production due to high dry matter and methane yields together with advanced breeding activities. In Germany nearly 80% of all energy crop biogas production is based on maize for silage. This dominance frequently causes environmental risks like soil erosion, nutrient losses and increased use of pesticides. Furthermore it puts societies’ acceptance towards biogas production increasingly at risk. Thus, the development of innovative cropping systems is essential for a sustainable energy crop production.This paper reviews results from 3 years field trials at seven locations with 12 different double-cropping systems (turnip rape, rye and mixture of rye–winterpea as first crops and maize, sorghum, sunflower and mixture of maize–sunflower as succeeding second crops) in comparison with three sole crops systems as references: maize and sunflower after mustard as catch crop and energy rye, harvested at dough ripeness as whole-crop silage.Double-cropping systems with rye or rye–pea as first crop and maize as second crop achieved highest DM yields of 23tDMha−1 on average, followed by sole cropped maize and double-cropping system of turnip rape and maize. Sole-cropped sunflowers had the lowest yield with nearly 15tDMha−1, followed by winter rye harvested at dough ripeness. Yields of other double-cropping systems had an intermediate position between those treatments. Methane yield per hectare was positively correlated with DM yield. Double cropping systems mostly achieved lower DM contents than sole cropping systems due to later sowing and altered photoperiodic influences. Further research on cultivars suitable for late sowing dates is necessary.Methane yield of crops was very similar with 282–298Nlkg−1 oDM, except for sorghum with 255Nlkg−1 oDM on average. Hence, differences in chemical components did not result in large changes regarding to methane yield, again except for sorghum, probably due to higher lignin contents.Double-cropping systems had mostly higher yield stability than sole cropping systems. The cultivation of two crops within 1 year may also spread the risk of weather extremes among two crops (or more if mixtures are grown) resulting in higher yield stability. This property is getting increasingly important with regard to climate change. Hence, double-cropping systems may contribute to a more sustainable energy crop production.

THE NATURE OF GENE ACTION AND THE PERFORMANCES OF HYBRIDS WITH RESPECT TO EARLINESS AND YIELD TRAITS UNDER NORMAL AND LATE SOWING DATES IN WHEAT (Triticum aestivum , L.).

This investigation was made to evaluate three bread wheat hybrids and their six populations generated from each of them under normal and late sowing dates. The three hybrids were obtained where hybrid 1 was a result of crossing (Late × Late) cultivars; hybrid 2 was a result of crossing (Early × Early) cultivars and hybrid 3 was a result of crossing (Late × Early) ones. The early parental in breed lines included: Line1, Line2 and Line3 while, thelate parental onesincluded: Misr2 and Gemmeiza9. The two sowing dates were: normal sowing on 29 November 2011 and the late sowing on 29 December 2011. Therefore, the total genetic materials were obtained from the three hybrids included 18 genotypes which were evaluated at Sakha Agricultural Research Station Farm, Wheat Section, Egypt. Earliness traits showed that late sowing date required fewer days than normal sowing date for days to heading; days to maturity and grain filling period. This trend was present for all populations of the three hybrids. It appeared that late sowing shorten the life span of plants. Yield component characters which included: plant height; 100- kernel weight and grain yield/ plant showed the advantage of hybrid 1 for plant height and grain yield/plant than the other two hybrids. These two characters showed a modest amounts of heterosis for the three hybrids. Nature of gene action which estimated from the six populations and evaluated using the scaling test analysis proposed by Mather and Jinks (1971). The results indicated the importance of additive genetic variance than dominance genetic variance one for most studied traits. These results were also supported by the results obtained from the scaling test analysis as the quantities A,B and C indicated the adequacy of the additive dominance model.

Filocrono e número de folhas da canola em diferentes condições ambientais

O objetivo deste trabalho foi determinar o número de folhas e o filocrono de genótipos de canola, em resposta a variações térmicas associadas com datas de semeadura. Foram realizados dois experimentos, em delineamento de blocos ao acaso, com arranjo fatorial de genótipos por datas de semeadura (5x2, em 2009, e 2x3 em 2010) e quatro repetições. O número de folhas do caule principal e do primeiro ramo foi determinado três vezes por semana. O filocrono foi estimado pelo inverso do coeficiente angular entre a soma térmica e o número de folhas, para os subperíodos da roseta e do alongamento do caule. O número de folhas no caule variou de 11,5 a 16,4; nos ramos, este número foi, em média, 70% menor. O número de folhas no caule foi maior em semeaduras precoces, e o inverso ocorreu no ramo. O filocrono foi maior no subperíodo da roseta e variou entre 21,4 e 52,9 graus-dia por folha conforme o genótipo e a data de semeadura. Semeaduras tardias aumentaram o filocrono. Genótipos de ciclo precoce apresentam número de folhas e filocrono menores que genótipos de ciclo médio ou longo, e a variabilidade entre os genótipos acentua-se em semeaduras tardias.

Examination of the impact of sowing technology models on the ear, constiuent and yield parameters of the yield formation elements of maize hybrids of different genotypes

Production year 2012 has been characterised by climatic extremities. The weather of this year can be considered very contradictory in terms of maize production. The droughty conditions of the winter and spring months had a negative effect on both germination and starting vigour. The favourable weather of May-July created ideal conditions for intensive growth and generative processes; however the lack of precipitation in August and September had a damaging effect on the development of yield composing elements and grain saturation processes as well. Under such circumstances, the sowing date models caused significant differences in the yield and quality of the hybrids belonging to different growth periods. The growing period of the maize hybrids has been shortened as a result of the unfavourable climatic conditions.&#x0D; Based on the trial results, it is verifiable that short growing period hybrids can be securely sown in draughty years even with a later sowing date, however using a later sowing date in the case of longer growth period hybrids may result even in a yield loss of 2–3 t ha-1. In the case of early and average sowing dates, with given yearly conditions the hybrids of the observed FAO 370-390 hybrid group provided the best result (12.40 t ha-1, 10.99 t ha-1), while in the case of the third, late sowing date the yield dominance of the FAO 290-350 hybrid group is the most significant (10.08 t ha-1).&#x0D; The analysis of the yield composing elements found that the P9578 hybrid has the highest shelling ratio, while its cob is the shortest. The P9494 hybrid has a high yield and the highest thousand grain weight, while the DKC 4983 has the longest cob and its thousand grain weight is above 300 g.&#x0D; The results confirm the fact that DKC 4590 has the highest yield potential and starch content, while in terms of oil and protein content the Szegedi 386 and NK Octet hybrids are the most important.

Diallel Analysis and Biochemical Genetic Markers for Heterosis and Combining Ability under Two Sowing Dates of Maize Inbred Lines

The study was undertaken to estimate heterosis and combining ability of new maize inbred lines in F1 combinations for some agronomic traits under two sowing dates for developing superior hybrids. Also this investigation studied the possibility of predicting heterosis and combining ability in maize inbred lines via protein electrophoresis. A half diallel set of crosses involving eight maize inbred lines were evaluated under two different sowing dates and the inbred lines were used for protein electrophoresis study. The obtained data revealed highly significant differences between sowing dates for all studied traits except number of rows per ear. The mean squares due to General Combining Ability (GCA) and Specific Combining Ability (SCA) were significant for all studied traits under both planting dates except 100 kernel weight under late planting date for SCA. GCA/SCA ratios were less than unity for plant height, days to 50% silking, 100 kernel weight and grain yield per plant under normal sowing date and ear height, plant height, number of kernel per row, 100 kernel weight and grain yield per plant under late sowing date and the other traits were more than unity. The hybrids P1 × P2, P1 × P6, P1 × P8, P2 × P5, P2 × P6, P3 × P6, P5 × P6, P5 × P7 and P6 × P7 under normal sowing date and P2 × P4, P2 × P5, P4 × P6 and P5 × P6 under late sowing date out yielded the check hybrid. The parental lines P2, P5 and P6 seemed to be the best combiners for grain yield per plant and most of the studied traits under normal and late planting dates. Twenty one out of the twenty eight crosses showed desirable significant SCA effects under normal and late sowing dates for grain yield per plant and most of the other studied traits. The electrophoresis patterns could be useful tools for the identification and characterization of these inbred lines and could be used as biochemical genetic markers associated with hybrid vigor and SCA in maize

Phenological development and grain yield of canola as affected by sowing date and climate variation in the Yangtze River Basin of China

Canola is a major oil crop in the Yangtze River Basin of China, and its yield and oil content vary significantly from year to year due to changes in sowing time and inter-annual climate variability. However, there have been no studies to quantify the impacts of sowing time and climate variability. Experimental data to analyse the response of canola growth to sowing date are limited to a few seasons; however, combining these data with modelling provides an efficient means to study the impact of sowing date and historical climate variation. The APSIM-Canola model was calibrated and tested using data from three field experimental sites in the Yangtze River Basin. These experiments included different cultivars and sowing dates, and recorded major phenological stages, biomass, and grain yield. After calibration of the phenological parameters and maximum harvest index, the model was able to simulate the onset of phenological stages with different sowing dates, and to explain 75% of the variation in biomass and yield caused by late sowings. However, the model overestimated canola yield under late sowing dates. The results revealed that canola yield declined linearly with late sowing time, mainly due to shortened vegetative growth stages, and varied significantly due to inter-annual climate variability. The yield potential at the study region is ~3 t/ha, on average. However, this potential cannot be achieved in the rice–canola double-cropping system due to later sowing time after rice harvest in mid–later October. Transplanting canola may still be an effective measure against the constraint of season length to achieving higher yields of both rice and canola.

GENETIC STUDIES ON GRAIN YIELD AND EARLINESS COMPONENTS IN BREAD WHEAT OF DIFFERENT PHOTO THERMAL RESPONSE

A diallel cross involving six bread wheat genotypes was evaluated to determine the genetic behaviour of earliness components as well as yield and its components in the F1 and F2 of bread wheat under optimum and late sowing dates conditions. In addition to thermal unit and susceptibility index, the resultant hybrids along (F1 and F2) with their parents were evaluated in two experiments. The first experement was planted in optimum sowing date on November 20th and the second one was planted in late sowing dates (Jan 1st) at field experement in Sids station, Agriculture Research Centre. Genotypes mean squares were significant for most studied characters in both experiments as well as thermal unit and susceptibility index. The obtained results showed that positive heterosis values over better parent values were detected for different studied characters. Inbreeding depression estimates were also significant and positive for grain filling rate and grain yield/plant in most crosses under both optimum and late sowing conditions.GCA variance values were two or more times higher than the SCA variance ones for days to maturity under both sowing dates, thermal unit under optimum sowing, grain filling period, grain filling rate and for grain yield/plant under both two sowing dates, suggesting the predominant of additive and additive x additive gene actions in controlling the studied characters. The early line (P2) could be considered as a good combiners for the early maturity, numbers of days and thermal unit under optimum and late sowing conditions. Parent Giza168 (P5) is a good combiner for the number of spikes/plant, grain yield/plant and its susceptibility index under late sowing condition while parent pastor (P4) could be considered as a good combiner for thermal unit under optimum sowing date and number of kernels/spike under late sowing and for grain filling period, grain filling rate and grain yield/plant under both optimum and late sowing dates. The best SCA values were detected by the cross P3xP5 for the earliness of maturity (number of days and thermal unit), grain filling period, grain filling rate, number of spikes/plant, susceptibility index of number of number kernels/spike, and grain yield/plant under optimum sowing date, also, cross P1xP4 was superior in number of spike/plant under both optimum and late, 100-kernel weight under optimum date and grain yield under late sowing. Moreover, cross P2 x P5 for grain yield/plant under optimum and late dates and its susceptibility, cross P3 x P4 for susceptibility index (SI) of No. of spikes/plant and for grain yield/plant under optimum and late dates cross P2 x P6 for grain yield under optimum sowing, cross P3 x P6 for days and thermal unit of heading and grain yield/plant and cross P4 x P5 gave the best SCA effects for grain yield/plant under late sowing condition.

Effect of sowing date and rate on canopy intercepted photo-synthetically active radiation and yield of winter wheat

小麦适期播种不仅是达到全苗壮苗的关键, 还有利于小麦健壮生长发育, 是提高小麦单产的重要措施。本试验研究了不同播期和播量条件下小麦冠层底部光合有效辐射(<i>TPAR</i>)、叶面积指数(<i>LAI</i>)、冠层截获的光合有效辐射(<i>IPAR</i>)等的变化及播期对冬小麦产量的影响。结果表明, 叶面积指数和冠层截获的光合有效辐射随小麦播种时间的推迟而降低, 小麦冠层底部的光合有效辐射随小麦播种时间的推迟而增大。小麦冠层截获的光合有效辐射与叶面积指数呈显著正相关, 相关系数为0.756; 冠层底部的光合有效辐射与叶面积呈显著负相关, 相关系数为-0.872。小麦产量虽然随播期的推迟呈递减趋势, 但10月20日之前播种的小麦产量间无显著差异。因此, 在冬小麦和夏玉米一年两熟区, 可相应推迟小麦的播种时间, 尽量延长上茬玉米的生长期, 以实现两茬作物的均衡增产。

Variation in branch length inFagopyrum esculentumin response to density and emergence date: No evidence for true plasticity

Plasticity is an important attribute that enables plants to maintain fitness in heterogeneous environments. The objective of this study was to investigate plasticity in branch length in Fagopyrum esculentum Moench. Seeds of the species were sown under two contrasting conditions through the manipulation of planting density (inter-planting distances at 20, 15, 10, and 5 cm) and sowing date (25 July, 1 August, 5 August, and 15 August). Allometric analysis of the relationships between branch length and total biomass showed a significant (p &lt; 0.05) departure from isometry. This indicates that branch length increased linearly as a function of size. However, branch length was smaller in the group of plants sown at higher densities and at late sowing dates. True plasticity, which would have been indicated by significant differences in allometric exponents within treatments, was not observed in this study. Our results suggest that the differences observed in branch length were due to the direct effect of size rather than as a result of true plastic investment in branches.

EFFECT OF SOWING AND HARVESTING DATES ON PRODUCTIVITY OF SOME SUGAR BEET VARIETIES UNDER SINAI CONDITIONS

Two field experiments were conducted in 2003/2004 and 2004/2005 seasons in Gelbana village, El-Kantra Shark, Sinai to study the effect of three sowing dates (30 September, 15 October and 5 November) and two harvesting dates ( 180 and 200 days after sowing) on productivity of five sugar beet varieties ( Top, Kawemira, Gloria, Pleno and Farida ) under sprinkler and drip irrigation systems. Sowing sugar beet under sprinkler or drip irrigation systems, at middle October recorded the highest root fresh weight/plant, root diameter and root length. Also, when sugar beet sown on 15 October, root and sugar yields/fed attained the highest values. On the other hand, the latest sowing date, namely 5 November produced the highest values of top fresh weight/plant, sucrose %, purity % and top yield/fed. Delaying harvest sugar beet from 180 till 200 days after sowing improved significantly the individual root characters and juice quality, as well as increased significantly root and sugar yields/fed. That held true under both irrigation systems in the two growing seasons. It was proved that sugar beet varieties differed under each irrigation system, where, Pleno cv. gave the highest values of root and top fresh weight/plant and root diameter under sprinkler irrigation, while Kawemira and Top cvs. were the best under drip irrigation. Concerning root and sugar yield as well as juice quality, Pleno, Kawemira and Top cvs. were the best under both irrigation systems.

EFFECT OF PLANTING DATES AND FOLIAR APPLICATION OF GIBBERELLIC ACID ON VEGETATIVE GROWTH, QUANTITY AND QUALITY OF YIELD IN TWO CULTIVARS OF CAULIFLOWER (Brassica oleracea var. botrytis)

This study was conducted in a private farm at Al-shallalat region approximately 15 km far from Mosul /Iraq during growing season of 2005_ 2006 to investigate the effect of three sowing dates (15th Aug, 1st Sept. and 15th Oct.), and the foliar application of GA3 at (0, 200 and 400 mg/l) on the vegetative growth, quantity and quality of curd yield in two Cauliflower cultivars Rami (Hybrid ) and White Cloud ( pure ). Treatment of GA3 were sprayed in two times, the first treatment was after a month of transplanting whereas the second treatment was done one month following the first spraying. The experiment involved 18 treatments arranged in a factorial experiment within split-plot using Randomized Complete Block Design with three replicates. The results could be summarized as follows: 1- White Cloud cv. Showed a significant increase in some vegetative growth (leaf number and leaf area), all yield quantity and quality characters (marketable curd weight, total marketable yield, curd circumference, curd thickness, curd color and curd compactment) as compared with Rami cv. Whereas Rami cv. revealed a significant decrease in the number of days from sowing to maturation 10٪ of curd as compared with the White Cloud cv. 2- Early sowing date (15th Aug) leads to a significant increase in all vegetative growth (leaf number and leaf area), all yield quantity and quality characters for both cultivars, whereas late sowing date (15th Oct) leads to a significant decrease in the number of days from sowing to maturation 10٪ of curd in the two cultivars 3- Treatment with GA3 at two concentrations (200 and 400 mg/l) showed a significant effects on average of marketable curd weight, total marketable yield, curd circumference and curd thickness, while it has no significant effects in the number of days from sowing to maturation 10٪ of curd, curd color and curd compactment. There where no significant effects between concentrations of GA3 in all the previous characters.

Sucrose metabolism in cotton ( Gossypium hirsutum L.) fibre under low temperature during fibre development

The effects of low temperature on sucrose content and activities of key enzymes related to sucrose metabolism in cotton ( Gossypium hirsutum L.) fibre were investigated. Two cotton cultivars, Kemian 1 and Sumian 15, were grown in the field at two sowing dates in 2006 and three sowing dates in 2007, the differences of environmental conditions during fibre development period (from flowering date to boll opening date) for different sowing dates were primarily on temperature. Low temperatures (MDTmin of 21.1, 20.5 and 18.1 °C) in late sowing dates (25 May/10 June) prolonged the fibre development period, and had significant effect on cellulose synthesis and sucrose metabolism. Results showed that, under low temperature, sucrose content was increased, cellulose content and sucrose transformation rate were decreased, and the variability of cellulose content and sucrose transformation rate through sowing dates in Sumian 15 was more than that in Kemian 1. The measurable activities of sucrose phosphate synthase (SPS), sucrose synthase (SuSy) and acid/alkaline invertases in sucrose metabolism were affected by low temperatures. Under low temperatures, activities of SuSy and invertase in sucrose degradation were increased, and two cultivars had the similar change. In contrast, the activity of SPS in sucrose synthesis was lower than the activity in developing fibre at normal environmental condition, and the time to peak activity was delayed, SPS activity in response to temperatures differed between two cultivars. The results indicated that restrained cellulose synthesis and sucrose metabolism under low temperature were mainly attributed to the changed activities of enzymes (SPS, SuSy and invertase), and the difference of cellulose synthesis and sucrose metabolism in response to temperature in fibre cells for two cotton cultivars was mainly determined by the level of SPS activity.

Factors limiting the grain protein content of organic winter wheat in south-eastern France: a mixed-model approach

Organic agriculture could achieve the objectives of sustainable agriculture by banning the use of synthetic fertilizers and pesticides. However, organic crops generally show lower performances than conventional ones. In France, organic winter wheat production is characterized by low grain protein content. There is a crucial need for better understanding the variability of grain protein content, because millers require batches with values over 10.5% of dry matter. Here, a regional agronomic diagnosis was carried out to identify the limiting factors and crop management practices explaining the variability of grain protein content. The studied field network was a set of 51 organic winter wheat plots in south-eastern France. The mixed-model method was used for identifying and ranking the limiting factors and the crop management practices responsible for variation in limiting factors. Our results show that the grain protein content variation was mostly explained by the baking quality grade of the cultivar, crop nitrogen status and weed density at flowering. There was a positive correlation between grain protein content and both crop nitrogen status and weed density. To a lesser extent, climatic factors also explained grain protein content variability. A lower water stress increased grain protein content, whereas an increase in the photothermal quotient and daily temperature over 25 °C reduced grain protein content. In south-eastern France, grain protein content of organic winter wheat could be increased by improving fertilization management, using an improved baking quality grade cultivar, choosing a legume fodder crop as preceding crop, or by avoiding late sowing dates.