过去几十年来，品种改良提高了小麦籽粒产量和氮肥利用效率，因此，21世纪长江流域小麦品种的籽粒产量和氮肥利用效率均高于先前的品种。但更高籽粒产量和氮肥利用效率的性状和机制还不清楚。为了探索这些新品种更高的籽粒产量和氮肥利用效率机制。本研究于2016-2019年连续3个生长季选择21个当地小麦品种进行栽培。三年度籽粒产量和氮肥利用效率均呈显著正相关关系。这些品种被分为高产高效、中产中效和低产低效类型（分别缩写为HH、MM和LL）。HH类型具有显著高的籽粒产量和氮肥利用效率。高产是由于通过高分蘖成穗率增加了有效穗数以及高花后单茎生物量增加了单穗产量。与其他类型相比，HH具有更强的花后叶面积持绿能力和更高的剑叶净光合速率。更高的花前氮素积累量增加了花前单茎氮素积累，包括茎鞘、叶片和单位叶面积，并且提高了氮肥吸收效率，这也是氮肥利用效率提高的主要原因。此外，分蘖成穗率与单茎氮素积累量、单位叶面积氮素积累量、叶片持绿能力和剑叶净光合速率均显著相关，表明，提升分蘖成穗率促进了氮素吸收、叶片氮素积累量和光合能力，从而实现籽粒产量和氮肥利用效率的协同提升。因此，分蘖成穗率被认为是一个可以用来品种选育和管理，以提高农业效率和可持续性的重要核心指标。

Cultivar selection is important for alfalfa (Medicago sativa L.) hay production. From 2009 to 2012, a field study was conducted to evaluate the dry matter yield (DMY) of 28 cultivars in Cangzhou District of Hebei province, China, and to determine the most suitable cultivars for this province and other zones with similar climate conditions. 28 alfalfa cultivars were sown in late March of 2009 and were harvested for hay four times in each subsequent year. The results showed that the climatic conditions resulted in significant differences in annual DMY among years, with the second year being the highest and the first year the lowest. The top five cultivars with the highest total DMY were L2750 (62.75 t ha-1), Horn (62.72 t ha-1), 86-266 (61.55 t ha-1), German (61.44 t ha-1) and Zhongmu 1 (61.18 t ha-1), respectively. Across all four years, first harvest had the highest ratios to annual DMY except the cultivar of Rambler, while the fourth harvest had the lowest ratio. There were positive correlation relationships between DMY of each harvest and annual DMY, and the correlation coefficients were all significant in four years. And the path coefficients of first harvest were always the highest in four years. The qualities showed small variations among these cultivars and the cultivar L3750 presented the highest crude protein in both years. Crude protein had significant positive correlation with relative feed value (RFV) in both years while crude fiber had significant negative correlation with RFV and crude fiber.

O3 is not only greenhouse gas but also a primary gaseous contaminant in the atmosphere. It has long-lasting effects on crop growth, yield and quality, and brings a series of ecological and environmental problems. A free-air controlled enrichment (FACE) system was applied to study the effect of elevated ozone concentration on activities of key enzymes of starch synthesis of Yangmai 16 in 2009-2010. The main-plot treatment had two levels of O3: ambient level (A-O3) and 50% higher than ambient level (E-O3). The main results were that accumulation rate of amylose, amylopectin and starch were represented in a single peak curve, and their content and accumulation amount rose gradually. The O3 elevation decreased the accumulation rate of amylose, amylopectin and starch amylase, reduced the accumulation amount of amylopectin and starch, and decreased the content of amylopectin and starch, but increased the content of amylose. With the increase of O3 concentration, the enzyme activity of grain granule-bound starch synthase (GBSS), soluble starch synthase (SSS) and starch branching enzyme (SBE) decreased after anthesis. The activities of GBSS and SSS had highly significant correlations with amylose, amylopectin and starch accumulation rate, and the activity of SBE had significant correlations with these items. So the O3 elevation decreased the activity of key enzymes of starch synthesis, which led to the variation of starch synthesis.

Phosphorus (P) is one of the most widely occurring nutrients for development and growth of wheat. In this study; the effects of P application amount on grain yield; protein content; and phosphorus use efficiency (PUE) were studied by agronomic management of P fertilizer on spring weak-gluten wheat (Triticum aestivum L.) grown under field conditions for  yr. The experiments were performed at five levels of PO application amount; including ; ; ; ; and  kg ha-. As a result; with increase in P fertilizer; grain yield; and P agricultural efficiency (AEP) increased in a quadratic equitation; but partial factor productivity of P (PFPP) decreased in a logarithmic eq. When  kg ha- PO was applied; the grain yield reached the highest level; but the protein content in gain was lower than .%; a threshold for the protein content to evaluate weak-gluten wheat suitable for production of cake and biscuit. Yangmai  and Ningmai  could tolerate to higher P level of soils than Yangmai  that had more loss in grain yield when P fertilizer was over-applied. AEP had a concomitant relationship with grain yield and was a better descriptor for P use efficiency in the wheat. A high P use efficiency resulted in leaf area index (LAI); increased chlorophyll content and photosynthetic rate; and stable acid phophatase (APase) activity to accumulate more dry matter after anthesis; which explained that the optimum P fertilizer increased grain yield and improved grain quality of weak-gluten wheat.