天水地区大果沙棘两个品种幼树生长规律研究

对天水地区两个品种大果沙棘的保存率、生长状况进行了分析.结果表明:楚伊、霞光4～6月份为速生期,属前期生长型树种,三年生平均树高141 cm、146 cm,地径2.5 cm、2.9 cm,冠幅123 cm,136 cm,保存率83.6%、94.0%,均表现出良好的适应性.霞光总体生长表现优于楚伊.     

高寒地区施肥对短芒老芒麦草产量和种子产量的影响(简报)

短芒老芒麦(Elymus breviaristatus Keng)是禾本科披碱草属多年生疏丛型牧草,属上繁草,适于刈割利用.因其分蘖力强,耐寒,叶量丰富,产草量高且草质柔软,是高寒牧区人工草地的优势草种.     

Steuben: a golden nematode resistant variety with wide adaptation

Steuben is a golden nematode resistant variety with wide adaptation and high yield potential. It has a mid to late season vine maturity but starts to size its crop of tubers as early as Superior. It has potential for tablestock as well as for chipping from the field and from 10°C storage. It is resistant to pitted scab but susceptible to superficial scab which can be severe enough to reduce its value for tablestock under some conditions. The maturity of the crop entering storage appears to be an important determinant for chip color out of storage.     

使用水稻收获机械的技术要点分析

推广应用水稻联合收获机械,减轻了稻农的劳动强度,提高了水稻生产效率。介绍水稻收获机械的分类,针对水稻联合收获机械操作技术不易掌握的实际情况,从农艺技术要求、作业前及作业中机械技术要求方面,总结水稻收获机械使用中应把握好的几个技术环节,以期为稻农熟练掌握其操作技术提供指导,提高机械的工作效率。     

考虑气象因子的不确定性灌溉水资源优化配置

基于不确定性区间作物水分生产函数,选取春小麦、玉米、棉花和白兰瓜这4种典型作物,建立不确定性条件下灌溉水资源优化配置模型,并将气象因子(蒸发蒸腾量和相对湿度)的不确定性引入其中,以反映气候变化对灌区配水的影响.结果表明,在石羊河流域民勤地区,玉米单方水经济效益较低,故其优化灌溉定额相比现状灌溉定额变化较大.棉花是单方水经济效益最大的作物,其次是白兰瓜,所以当可用水量短缺时,在确保粮食安全的前提下,为降低因灌溉缺水而带来的经济损失,要优先保证棉花和白兰瓜灌溉用水.引入气象因子的灌区水资源优化配置模型区间优化配水定额范围更广,反映出气象因子对灌区配水的影响.本研究验证了不确定性方法在实际应用的可行性,可为灌区水资源合理分配提供更可靠的科学依据.     

施肥对青藏高原燕麦种子产量及产量组分的影响

燕麦(Avena sativa L.)是一种适应于青藏高原生长、且有较高营养价值的栽培牧草,在高寒牧区冬春季节的家畜补饲中起着非常重要的作用,由于青藏高原海拔高、气候寒冷,燕麦种子产量较低,远远不能满足目前逐年增加的种子需求量.通过研究施肥水平对燕麦种子产量和品质的影响,筛选出适宜燕麦种子高产的施肥量,可为提高燕麦种子生产能力提供直接的理论依据.本研究结果表明:施氮对燕麦产量和品质影响作用明显,施氮水平与种子蛋白质含量之间呈显著的线性回归关系(R=0.896 8,p<0.01),随着施肥量的增加.蛋白质含量持续增加;而施氮水平与有效分蘖数、小稳数和种子产量之间呈显著的二次回归关系(p<0.01),表现为"低-高-低"的变化趋势,施氮量60kg/hm2时燕麦种子产量为4 358.5 kg/hm2,达到最高,施肥量继续增加,种子产量增幅下降.因此,从高产和高效角度综合考虑,生产中在以收获燕麦种子为目的时,施氮量应选择60 kg/hm2.     

Random amplified polymorphic DNA variation within and among meadow bromegrass progeny types

Ten meadow bromegrass genotypes tested as half‐sib (polycross, PX; open‐pollinated, OP) and selfed (S₁) progenies were surveyed using random amplified polymorphic DNA. Fourteen primers, which produced 32 markers, were selected to determine the genotypes of 360 individuals from the three progeny tests. Analysis of molecular variance was performed in each progeny test, and genetic distances between genotypes and progeny types were determined. Among genotype genetic variation in half‐sib (PX and OP) progenies was similar. Genetic variation among genotypes for S₁ progenies (30.5%) was about twice that found in the half‐sib progenies. Variation between individual S₁ progenies ranged from 15.7% to 50.1%, while in the half‐sib progenies, the range was 6.9‐24.1%. Based on average distances between progeny types for a given genotype, OP and PX were closer to each other than to the S₁. An analysis of variance of the molecular marker frequency occurrence was performed for 12 plants within each progeny type of each genotype. Marker frequencies, expressed in percentages, ranged from 10.7% to 84.3%. No significant differences were found for genotype and progeny type‐genotype interaction suggesting that all genotypes behave in a similar manner across the different progeny types.     

Further cytological characteristics of a male-sterile mutant in soybean affecting cytokinesis and microspore development

A spontaneous male‐sterile mutation affecting microspore development has been found in BR97‐13509H line of the official Brazilian soybean breeding programme. Slightly abnormal and irregular chromosome segregation occurred in both meiotic divisions, albeit insufficient to explain total pollen sterility. The main cause of male sterility was the absence of cytokinesis after telophase II. Instead of the typical tetrads of microspores, four‐nucleate coenocytic microspores were formed. Coenocytic microspores resulting from the absence of cytokinesis have also been described in ms1 and ms4 male‐sterile soybean mutants, although with certain differential characteristics. In the BR97‐13509H mutant line, after interphase the four nuclei were rejoined in one or two metaphase plates and progressed through the first pollen mitosis. Pollen then underwent a progressive process of degeneration characterized by continuous cytoplasmic shrinkage. The second pollen mitosis failed to occur, and pollen sterility became total.