果树栽植机光电定株距装置的设计与试验

针对果树栽植过程中株距难以控制的问题,考虑到现有的果树栽植机定株距存在结构复杂、制造成本高及受土壤滑移率影响较大等问题,设计了一种光电定株距装置,可以避免土壤滑移率对株距的影响,保证栽植果树株距的一致性,且可实现株距连续可调,满足不同果树栽植时对株距选择的要求。针对试验中出现的部分株距较设计值有所偏差的问题,分析了原因并提出了优化方案。试验结果表明:果树栽植机光电定株距装置栽植合格率92.5%,平均栽植深度合格率为92.9%,在1.7m栽植株距下,株距变异系数为5.9%,满足现代标准果园机械化生产要求。     

Spatial variability in the growth of direct-seeded rainfed lowland rice (Oryza sativa L.) in northeast Thailand

Large within-field variation in rice growth often causes production loss in broadcast-seeded (BC) rainfed lowland rice. The spatial variability of direct-seeded rainfed lowland rice was evaluated in 2004, 2005, and 2007 in on-station experiments at Ubon Ratchathani, northeast Thailand, in relation to soil water content and weed infestation, by adopting semivariogram and block kriging, including comparisons among BC with harrowing (BCH; no weeding), BC with no harrowing (BCNH; no weeding), and row-seeded (RS; interrow weeding once) fields. BCH and BCNH were also compared in 11 farmers’ fields in 2006 and 2007, to assess the effect of harrowing on rice growth and weed infestation. During most of the rice growing periods, flooded and non-flooded portions existed simultaneously in the fields, with different proportions among years and among seeding methods in the on-station experiment. BCH and BCNH rice had large within-field variation in seedling density, heading date, shoot dry matter, grain yield, harvest index, panicle density, and filled spikelet per panicle, as well as in weed infestation, measured by a quick visual estimation. Many of the measured variables (except mean soil water content in RS in 2007, seedling density in BCH in 2005 and 2007, shoot dry matter in BCH and BCNH in 2007, and panicle density in BCH in 2007) were spatially dependent (i.e., data from nearby locations were most similar) by geostatistical analysis. Analysis of correlations using the 420 data sets of BCH plots in 2005 and BCH, BCNH, and RS plots in 2007 revealed a positive correlation between soil water content and grain yield and negative correlations between weed infestation and soil water content and grain yield. Compared with BCH, in 2007 BCNH had much lower grain yield because of lower soil water content after establishment and more weed infestation. BCH had higher grain yield than BCNH in weedy fields in the farmers’ fields experiment. RS with interrow weeding resulted in a smaller coefficient of variation, smaller sill value, and higher grain yield than BCH, due to less weed infestation and a higher proportion of flooded water. These results indicated that reducing the spatial variability in rice growth requires careful field preparation, such as harrowing to level the soil surface and to reduce the uneven distribution of standing water and the variability in soil water content, combined with effective crop and weed management (i.e., harrowing and row-seeding). This is the first study that examined spatial variability in the growth of direct-seeded rice as a function of soil water content and weed infestation in a rainfed lowland environment.     

A dual-spectral camera system for paddy rice seedling row detection

A new method is presented for detecting rows of rice seedlings to facilitate the navigation of rice transplanters. Generally, an independent NIR or RGB camera is used as a vision sensor for agricultural vehicles; however, strong reflections on the water surface make row detection more difficult in flooded paddy fields compared to dry fields. To solve this problem, we developed a dual-spectral camera system that consists of a pair of low-cost monochrome cameras with optical filters. Different wavelength images of the same location can be taken simultaneously in real-time. An experiment conducted under cloudy conditions showed that this system could reduce water surface noise and clearly detect seedling rows.     

主要栽培措施对烤烟总氮含量的影响

采用五因素二次正交回归旋转组合设计,以株距(X1)、氮肥用量(X2)、打顶时间(X3)、硼肥浓度(X4)、IAA浓度(X5)为研究对象,建立了株距、氮肥用量、打顶时间、硼肥浓度、IAA浓度与烤烟总氮含量的数学模型;解析了数学模型,并给出各因子的理想搭配模式及其适宜取值范围。结果表明:最适宜的栽培组合为株距50 cm,氮肥用量80 kg/hm2,打顶时间为现蕾后10 d,硼肥浓度为6 g/kg,IAA浓度为30 mg/kg。     

行距配置对大穗型品种兰考矮早八旗叶氮代谢酶活性、籽粒产量及蛋白质含量的影响

在大田高产栽培条件下。研究了行距配置对大穗型冬小麦品种兰考矮早八花后旗叶硝酸还原酶活性、谷氨酰胺合成酶活性、籽粒产量、蛋白质含量及单位面积蛋白质产量的影响。结果表明,15cm行距处理下,旗叶在灌浆中后期具有较高的氮代谢酶活性。籽粒产量随行距减小而增加,而籽粒蛋白质含量却减小,籽粒蛋白质产量与籽粒产量表现相同趋势。因此,适当缩小种植行距,降低了籽粒蛋白质含量,但有利于提高籽粒产量和单位面积蛋白质产量。     

行距配置对大穗型品种兰考矮早八旗叶氮代谢酶活性、籽粒产量及蛋白质含量的影响

在大田高产栽培条件下。研究了行距配置对大穗型冬小麦品种兰考矮早八花后旗叶硝酸还原酶活性、谷氨酰胺合成酶活性、籽粒产量、蛋白质含量及单位面积蛋白质产量的影响。结果表明,15cm行距处理下,旗叶在灌浆中后期具有较高的氮代谢酶活性。籽粒产量随行距减小而增加,而籽粒蛋白质含量却减小,籽粒蛋白质产量与籽粒产量表现相同趋势。因此,适当缩小种植行距,降低了籽粒蛋白质含量,但有利于提高籽粒产量和单位面积蛋白质产量。     

辽东山区落叶松人工纯林诱导复层林更新试验

对辽宁东部山区落叶松人工纯林进行不同行状间伐试验,并在采伐迹地进行云杉幼树更新试验,试验结果发现:落叶松纯林经过行状间伐,草本层生物多样性显著增加,林地土壤持水力增强,增幅为4.4%～16.7%.不同更新行数试验的云杉幼树年均高生长量、冠幅生长量、地径生长量、总生物量大小变化明显,伐2行栽1行型与全光对比分别减少了27.4%、12.7%、21.7%、4.1%,而伐3栽2型分别增加了3.6%、0.8%、4.3%、15.8%.伐后保留带落叶松的生长得到了促进,2 a后落叶松的胸径、单株材积都比同龄落叶松纯林大,伐2栽1型与伐3栽2型增幅分别为2.7%～8%、4.6%～16.7%;高生长变化不明显.     

不同初植密度的桉树人工林经济效益分析

通过分析1993年设立于广西东门林场的桉树人工林5种造林密度(1)2 222株·hm-2、(2)1 667株·hm-2、(3)1 250株·hm-2、(4)883株·hm-2和(5)667株·hm-212年的生长数据,计算了连年生长量、平均生长量、材种出材量、净现值和内部收益率.结果显示,6.3 a前5种密度蓄积生长量的差距达到极显著水平,8.3 a以后差异就不再显著;密度2 222株·hm-2、1 667株·hm-2和1 250株·hm-2的数量成熟均为6 a,密度883株·hm-2为6.5 a,密度667株·hm-2为7 a;造林密度越大,纸浆材的出材比例越高,而大、中径材出材比例越小,造林密度小,锯材和旋切材的出材比例更高;密度2 222株·hm-2、1 667株·hm-2、1 250株·hm-2、883株·hm-2和667株·hm-2的轮伐期分别为6 a、7 a、7 a、7 a和8 a,这时的净现值分别是17 661、18 457、22 257、24 755和24 007元·hm-2,内部收益率分别为56%、50%、55%、58%和51%;密度883株·hm-2有最高的净现值和内部收益率,是5种密度中最好的造林密度,其他从大到小的顺序是密度667株·hm-2、1 250株·hm-2、1 667株·hm-2和2 222株·hm-2.     

Fruit production and quality improvement in aonla （Emblica Officinalis Gaertn.） through canopy management

In order to maintain the health and vigour and to sustain the productivity, a pruning experiment was conducted on four year old ＂Balwant＂ cultivar of aonla grown in laterite soil, planted at a spacing of 5m×5m. To find out the best pruning method, six levels of pruning was performed i.e., （1） Light judicious pruning, （2） Detopping of primary branches at 8 feet from ground level ＋ removal of all secondary branches, （3） Detopping of primary branches at 8 feet from the ground level ＋ removal of all secondary branches at 2 feet from the base of primary branches, （4） Detopping of primary branches at 8 feet from the ground level ＋ removal of all secondary branches at 1 feet from the base of primary branches, （5） Light judicious pruning ＋ Detopping of plant canopy of at 8 feet from the ground level, （6） No pruning （control）. Results of three consecutive years of investigation revealed that light judicious pruning of thin, overlapping, criss-crossed, dead, unproductive and looping branches gave highest fruit yield in all the three years and resulted 64.4 percent yield increment over control when average of three years was considered. Severe pruning of primary and secondary branches caused drastic reduction of yield for two consecutive years after pruning. Judicious pruning helped to produce better sizeable and quality fruits.     

行向对不同穗型水稻品种群体光环境的影响

调查行向对不同穗型水稻群体光分布的影响,结果表明：无论直立穗型还是弯曲穗型,均是南北行向较东西行向多受光;无论南北行向还是东西行向,直立穗型群体内各高度处光照强度大于弯曲穗型群体;直立穗型品种和弯曲穗型品种均适于南北行向种植。